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<header> 91 <div class="header-container"> 92 <h1>Node.js v14.19.1 documentation</h1> 93 <button class="theme-toggle-btn" id="theme-toggle-btn" title="Toggle dark mode/light mode" aria-label="Toggle dark mode/light mode" hidden> 94 <svg xmlns="http://www.w3.org/2000/svg" class="icon dark-icon" height="24" width="24"> 95 <path fill="none" d="M0 0h24v24H0z" /> 96 <path d="M11.1 12.08c-2.33-4.51-.5-8.48.53-10.07C6.27 2.2 1.98 6.59 1.98 12c0 .14.02.28.02.42.62-.27 1.29-.42 2-.42 1.66 0 3.18.83 4.1 2.15A4.01 4.01 0 0111 18c0 1.52-.87 2.83-2.12 3.51.98.32 2.03.5 3.11.5 3.5 0 6.58-1.8 8.37-4.52-2.36.23-6.98-.97-9.26-5.41z"/> 97 <path d="M7 16h-.18C6.4 14.84 5.3 14 4 14c-1.66 0-3 1.34-3 3s1.34 3 3 3h3c1.1 0 2-.9 2-2s-.9-2-2-2z"/> 98 </svg> 99 <svg xmlns="http://www.w3.org/2000/svg" class="icon light-icon" height="24" width="24"> 100 <path d="M0 0h24v24H0z" fill="none" /> 101 <path d="M6.76 4.84l-1.8-1.79-1.41 1.41 1.79 1.79 1.42-1.41zM4 10.5H1v2h3v-2zm9-9.95h-2V3.5h2V.55zm7.45 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href="https://nodejs.org/docs/latest-v13.x/api/buffer.html">13.x</a></li> 124<li><a href="https://nodejs.org/docs/latest-v12.x/api/buffer.html">12.x <b>LTS</b></a></li> 125<li><a href="https://nodejs.org/docs/latest-v11.x/api/buffer.html">11.x</a></li> 126<li><a href="https://nodejs.org/docs/latest-v10.x/api/buffer.html">10.x</a></li> 127<li><a href="https://nodejs.org/docs/latest-v9.x/api/buffer.html">9.x</a></li> 128<li><a href="https://nodejs.org/docs/latest-v8.x/api/buffer.html">8.x</a></li> 129<li><a href="https://nodejs.org/docs/latest-v7.x/api/buffer.html">7.x</a></li> 130<li><a href="https://nodejs.org/docs/latest-v6.x/api/buffer.html">6.x</a></li> 131<li><a href="https://nodejs.org/docs/latest-v5.x/api/buffer.html">5.x</a></li> 132<li><a href="https://nodejs.org/docs/latest-v4.x/api/buffer.html">4.x</a></li> 133<li><a href="https://nodejs.org/docs/latest-v0.12.x/api/buffer.html">0.12.x</a></li> 134<li><a href="https://nodejs.org/docs/latest-v0.10.x/api/buffer.html">0.10.x</a></li></ol> 135 </li> 136 137 <li class="edit_on_github"><a href="https://github.com/nodejs/node/edit/master/doc/api/buffer.md">Edit on GitHub</a></li> 138 </ul> 139 </div> 140 <hr> 141 </header> 142 143 <details id="toc" open><summary>Table of contents</summary><ul> 144<li><span class="stability_2"><a href="#buffer_buffer">Buffer</a></span> 145<ul> 146<li><a href="#buffer_buffers_and_character_encodings">Buffers and character encodings</a></li> 147<li><a href="#buffer_buffers_and_typedarrays">Buffers and TypedArrays</a></li> 148<li><a href="#buffer_buffers_and_iteration">Buffers and iteration</a></li> 149<li><span class="stability_1"><a href="#buffer_class_blob">Class: <code>Blob</code></a></span> 150<ul> 151<li><a href="#buffer_new_buffer_blob_sources_options"><code>new buffer.Blob([sources[, options]])</code></a></li> 152<li><a href="#buffer_blob_arraybuffer"><code>blob.arrayBuffer()</code></a></li> 153<li><a href="#buffer_blob_size"><code>blob.size</code></a></li> 154<li><a href="#buffer_blob_slice_start_end_type"><code>blob.slice([start, [end, [type]]])</code></a></li> 155<li><a href="#buffer_blob_text"><code>blob.text()</code></a></li> 156<li><a href="#buffer_blob_type"><code>blob.type</code></a></li> 157<li><a href="#buffer_blob_objects_and_messagechannel"><code>Blob</code> objects and <code>MessageChannel</code></a></li> 158</ul> 159</li> 160<li><a href="#buffer_class_buffer">Class: <code>Buffer</code></a> 161<ul> 162<li><a href="#buffer_static_method_buffer_alloc_size_fill_encoding">Static method: <code>Buffer.alloc(size[, fill[, encoding]])</code></a></li> 163<li><a href="#buffer_static_method_buffer_allocunsafe_size">Static method: <code>Buffer.allocUnsafe(size)</code></a></li> 164<li><a href="#buffer_static_method_buffer_allocunsafeslow_size">Static method: <code>Buffer.allocUnsafeSlow(size)</code></a></li> 165<li><a href="#buffer_static_method_buffer_bytelength_string_encoding">Static method: <code>Buffer.byteLength(string[, encoding])</code></a></li> 166<li><a href="#buffer_static_method_buffer_compare_buf1_buf2">Static method: <code>Buffer.compare(buf1, buf2)</code></a></li> 167<li><a href="#buffer_static_method_buffer_concat_list_totallength">Static method: <code>Buffer.concat(list[, totalLength])</code></a></li> 168<li><a href="#buffer_static_method_buffer_from_array">Static method: <code>Buffer.from(array)</code></a></li> 169<li><a href="#buffer_static_method_buffer_from_arraybuffer_byteoffset_length">Static method: <code>Buffer.from(arrayBuffer[, byteOffset[, length]])</code></a></li> 170<li><a href="#buffer_static_method_buffer_from_buffer">Static method: <code>Buffer.from(buffer)</code></a></li> 171<li><a href="#buffer_static_method_buffer_from_object_offsetorencoding_length">Static method: <code>Buffer.from(object[, offsetOrEncoding[, length]])</code></a></li> 172<li><a href="#buffer_static_method_buffer_from_string_encoding">Static method: <code>Buffer.from(string[, encoding])</code></a></li> 173<li><a href="#buffer_static_method_buffer_isbuffer_obj">Static method: <code>Buffer.isBuffer(obj)</code></a></li> 174<li><a href="#buffer_static_method_buffer_isencoding_encoding">Static method: <code>Buffer.isEncoding(encoding)</code></a></li> 175<li><a href="#buffer_class_property_buffer_poolsize">Class property: <code>Buffer.poolSize</code></a></li> 176<li><a href="#buffer_buf_index"><code>buf[index]</code></a></li> 177<li><a href="#buffer_buf_buffer"><code>buf.buffer</code></a></li> 178<li><a href="#buffer_buf_byteoffset"><code>buf.byteOffset</code></a></li> 179<li><a href="#buffer_buf_compare_target_targetstart_targetend_sourcestart_sourceend"><code>buf.compare(target[, targetStart[, targetEnd[, sourceStart[, sourceEnd]]]])</code></a></li> 180<li><a href="#buffer_buf_copy_target_targetstart_sourcestart_sourceend"><code>buf.copy(target[, targetStart[, sourceStart[, sourceEnd]]])</code></a></li> 181<li><a href="#buffer_buf_entries"><code>buf.entries()</code></a></li> 182<li><a href="#buffer_buf_equals_otherbuffer"><code>buf.equals(otherBuffer)</code></a></li> 183<li><a href="#buffer_buf_fill_value_offset_end_encoding"><code>buf.fill(value[, offset[, end]][, encoding])</code></a></li> 184<li><a href="#buffer_buf_includes_value_byteoffset_encoding"><code>buf.includes(value[, byteOffset][, encoding])</code></a></li> 185<li><a href="#buffer_buf_indexof_value_byteoffset_encoding"><code>buf.indexOf(value[, byteOffset][, encoding])</code></a></li> 186<li><a href="#buffer_buf_keys"><code>buf.keys()</code></a></li> 187<li><a href="#buffer_buf_lastindexof_value_byteoffset_encoding"><code>buf.lastIndexOf(value[, byteOffset][, encoding])</code></a></li> 188<li><a href="#buffer_buf_length"><code>buf.length</code></a></li> 189<li><span class="stability_0"><a href="#buffer_buf_parent"><code>buf.parent</code></a></span></li> 190<li><a href="#buffer_buf_readbigint64be_offset"><code>buf.readBigInt64BE([offset])</code></a></li> 191<li><a href="#buffer_buf_readbigint64le_offset"><code>buf.readBigInt64LE([offset])</code></a></li> 192<li><a href="#buffer_buf_readbiguint64be_offset"><code>buf.readBigUInt64BE([offset])</code></a></li> 193<li><a href="#buffer_buf_readbiguint64le_offset"><code>buf.readBigUInt64LE([offset])</code></a></li> 194<li><a href="#buffer_buf_readdoublebe_offset"><code>buf.readDoubleBE([offset])</code></a></li> 195<li><a href="#buffer_buf_readdoublele_offset"><code>buf.readDoubleLE([offset])</code></a></li> 196<li><a href="#buffer_buf_readfloatbe_offset"><code>buf.readFloatBE([offset])</code></a></li> 197<li><a href="#buffer_buf_readfloatle_offset"><code>buf.readFloatLE([offset])</code></a></li> 198<li><a href="#buffer_buf_readint8_offset"><code>buf.readInt8([offset])</code></a></li> 199<li><a href="#buffer_buf_readint16be_offset"><code>buf.readInt16BE([offset])</code></a></li> 200<li><a href="#buffer_buf_readint16le_offset"><code>buf.readInt16LE([offset])</code></a></li> 201<li><a href="#buffer_buf_readint32be_offset"><code>buf.readInt32BE([offset])</code></a></li> 202<li><a href="#buffer_buf_readint32le_offset"><code>buf.readInt32LE([offset])</code></a></li> 203<li><a href="#buffer_buf_readintbe_offset_bytelength"><code>buf.readIntBE(offset, byteLength)</code></a></li> 204<li><a href="#buffer_buf_readintle_offset_bytelength"><code>buf.readIntLE(offset, byteLength)</code></a></li> 205<li><a href="#buffer_buf_readuint8_offset"><code>buf.readUInt8([offset])</code></a></li> 206<li><a href="#buffer_buf_readuint16be_offset"><code>buf.readUInt16BE([offset])</code></a></li> 207<li><a href="#buffer_buf_readuint16le_offset"><code>buf.readUInt16LE([offset])</code></a></li> 208<li><a href="#buffer_buf_readuint32be_offset"><code>buf.readUInt32BE([offset])</code></a></li> 209<li><a href="#buffer_buf_readuint32le_offset"><code>buf.readUInt32LE([offset])</code></a></li> 210<li><a href="#buffer_buf_readuintbe_offset_bytelength"><code>buf.readUIntBE(offset, byteLength)</code></a></li> 211<li><a href="#buffer_buf_readuintle_offset_bytelength"><code>buf.readUIntLE(offset, byteLength)</code></a></li> 212<li><a href="#buffer_buf_subarray_start_end"><code>buf.subarray([start[, end]])</code></a></li> 213<li><a href="#buffer_buf_slice_start_end"><code>buf.slice([start[, end]])</code></a></li> 214<li><a href="#buffer_buf_swap16"><code>buf.swap16()</code></a></li> 215<li><a href="#buffer_buf_swap32"><code>buf.swap32()</code></a></li> 216<li><a href="#buffer_buf_swap64"><code>buf.swap64()</code></a></li> 217<li><a href="#buffer_buf_tojson"><code>buf.toJSON()</code></a></li> 218<li><a href="#buffer_buf_tostring_encoding_start_end"><code>buf.toString([encoding[, start[, end]]])</code></a></li> 219<li><a href="#buffer_buf_values"><code>buf.values()</code></a></li> 220<li><a href="#buffer_buf_write_string_offset_length_encoding"><code>buf.write(string[, offset[, length]][, encoding])</code></a></li> 221<li><a href="#buffer_buf_writebigint64be_value_offset"><code>buf.writeBigInt64BE(value[, offset])</code></a></li> 222<li><a href="#buffer_buf_writebigint64le_value_offset"><code>buf.writeBigInt64LE(value[, offset])</code></a></li> 223<li><a href="#buffer_buf_writebiguint64be_value_offset"><code>buf.writeBigUInt64BE(value[, offset])</code></a></li> 224<li><a href="#buffer_buf_writebiguint64le_value_offset"><code>buf.writeBigUInt64LE(value[, offset])</code></a></li> 225<li><a href="#buffer_buf_writedoublebe_value_offset"><code>buf.writeDoubleBE(value[, offset])</code></a></li> 226<li><a href="#buffer_buf_writedoublele_value_offset"><code>buf.writeDoubleLE(value[, offset])</code></a></li> 227<li><a href="#buffer_buf_writefloatbe_value_offset"><code>buf.writeFloatBE(value[, offset])</code></a></li> 228<li><a href="#buffer_buf_writefloatle_value_offset"><code>buf.writeFloatLE(value[, offset])</code></a></li> 229<li><a href="#buffer_buf_writeint8_value_offset"><code>buf.writeInt8(value[, offset])</code></a></li> 230<li><a href="#buffer_buf_writeint16be_value_offset"><code>buf.writeInt16BE(value[, offset])</code></a></li> 231<li><a href="#buffer_buf_writeint16le_value_offset"><code>buf.writeInt16LE(value[, offset])</code></a></li> 232<li><a href="#buffer_buf_writeint32be_value_offset"><code>buf.writeInt32BE(value[, offset])</code></a></li> 233<li><a href="#buffer_buf_writeint32le_value_offset"><code>buf.writeInt32LE(value[, offset])</code></a></li> 234<li><a href="#buffer_buf_writeintbe_value_offset_bytelength"><code>buf.writeIntBE(value, offset, byteLength)</code></a></li> 235<li><a href="#buffer_buf_writeintle_value_offset_bytelength"><code>buf.writeIntLE(value, offset, byteLength)</code></a></li> 236<li><a href="#buffer_buf_writeuint8_value_offset"><code>buf.writeUInt8(value[, offset])</code></a></li> 237<li><a href="#buffer_buf_writeuint16be_value_offset"><code>buf.writeUInt16BE(value[, offset])</code></a></li> 238<li><a href="#buffer_buf_writeuint16le_value_offset"><code>buf.writeUInt16LE(value[, offset])</code></a></li> 239<li><a href="#buffer_buf_writeuint32be_value_offset"><code>buf.writeUInt32BE(value[, offset])</code></a></li> 240<li><a href="#buffer_buf_writeuint32le_value_offset"><code>buf.writeUInt32LE(value[, offset])</code></a></li> 241<li><a href="#buffer_buf_writeuintbe_value_offset_bytelength"><code>buf.writeUIntBE(value, offset, byteLength)</code></a></li> 242<li><a href="#buffer_buf_writeuintle_value_offset_bytelength"><code>buf.writeUIntLE(value, offset, byteLength)</code></a></li> 243<li><span class="stability_0"><a href="#buffer_new_buffer_array"><code>new Buffer(array)</code></a></span></li> 244<li><span class="stability_0"><a href="#buffer_new_buffer_arraybuffer_byteoffset_length"><code>new Buffer(arrayBuffer[, byteOffset[, length]])</code></a></span></li> 245<li><span class="stability_0"><a href="#buffer_new_buffer_buffer"><code>new Buffer(buffer)</code></a></span></li> 246<li><span class="stability_0"><a href="#buffer_new_buffer_size"><code>new Buffer(size)</code></a></span></li> 247<li><span class="stability_0"><a href="#buffer_new_buffer_string_encoding"><code>new Buffer(string[, encoding])</code></a></span></li> 248</ul> 249</li> 250<li><a href="#buffer_buffer_module_apis"><code>buffer</code> module APIs</a> 251<ul> 252<li><a href="#buffer_buffer_atob_data"><code>buffer.atob(data)</code></a></li> 253<li><a href="#buffer_buffer_btoa_data"><code>buffer.btoa(data)</code></a></li> 254<li><a href="#buffer_buffer_inspect_max_bytes"><code>buffer.INSPECT_MAX_BYTES</code></a></li> 255<li><a href="#buffer_buffer_kmaxlength"><code>buffer.kMaxLength</code></a></li> 256<li><a href="#buffer_buffer_kstringmaxlength"><code>buffer.kStringMaxLength</code></a></li> 257<li><a href="#buffer_buffer_transcode_source_fromenc_toenc"><code>buffer.transcode(source, fromEnc, toEnc)</code></a></li> 258<li><span class="stability_0"><a href="#buffer_class_slowbuffer">Class: <code>SlowBuffer</code></a></span> 259<ul> 260<li><span class="stability_0"><a href="#buffer_new_slowbuffer_size"><code>new SlowBuffer(size)</code></a></span></li> 261</ul> 262</li> 263<li><a href="#buffer_buffer_constants">Buffer constants</a> 264<ul> 265<li><a href="#buffer_buffer_constants_max_length"><code>buffer.constants.MAX_LENGTH</code></a></li> 266<li><a href="#buffer_buffer_constants_max_string_length"><code>buffer.constants.MAX_STRING_LENGTH</code></a></li> 267</ul> 268</li> 269</ul> 270</li> 271<li><a href="#buffer_buffer_from_buffer_alloc_and_buffer_allocunsafe"><code>Buffer.from()</code>, <code>Buffer.alloc()</code>, and <code>Buffer.allocUnsafe()</code></a> 272<ul> 273<li><a href="#buffer_the_zero_fill_buffers_command_line_option">The <code>--zero-fill-buffers</code> command-line option</a></li> 274<li><a href="#buffer_what_makes_buffer_allocunsafe_and_buffer_allocunsafeslow_unsafe">What makes <code>Buffer.allocUnsafe()</code> and <code>Buffer.allocUnsafeSlow()</code> "unsafe"?</a></li> 275</ul> 276</li> 277</ul> 278</li> 279</ul></details> 280 281 <div id="apicontent"> 282 <h2>Buffer<span><a class="mark" href="#buffer_buffer" id="buffer_buffer">#</a></span></h2> 283 284<p></p><div class="api_stability api_stability_2"><a href="documentation.html#documentation_stability_index">Stability: 2</a> - Stable</div><p></p> 285<p><strong>Source Code:</strong> <a href="https://github.com/nodejs/node/blob/v14.19.1/lib/buffer.js">lib/buffer.js</a></p> 286<p><code>Buffer</code> objects are used to represent a fixed-length sequence of bytes. Many 287Node.js APIs support <code>Buffer</code>s.</p> 288<p>The <code>Buffer</code> class is a subclass of JavaScript's <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Uint8Array"><code>Uint8Array</code></a> class and 289extends it with methods that cover additional use cases. Node.js APIs accept 290plain <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Uint8Array"><code>Uint8Array</code></a>s wherever <code>Buffer</code>s are supported as well.</p> 291<p>The <code>Buffer</code> class is within the global scope, making it unlikely that one 292would need to ever use <code>require('buffer').Buffer</code>.</p> 293<pre><code class="language-js"><span class="hljs-comment">// Creates a zero-filled Buffer of length 10.</span> 294<span class="hljs-keyword">const</span> buf1 = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">alloc</span>(<span class="hljs-number">10</span>); 295 296<span class="hljs-comment">// Creates a Buffer of length 10,</span> 297<span class="hljs-comment">// filled with bytes which all have the value `1`.</span> 298<span class="hljs-keyword">const</span> buf2 = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">alloc</span>(<span class="hljs-number">10</span>, <span class="hljs-number">1</span>); 299 300<span class="hljs-comment">// Creates an uninitialized buffer of length 10.</span> 301<span class="hljs-comment">// This is faster than calling Buffer.alloc() but the returned</span> 302<span class="hljs-comment">// Buffer instance might contain old data that needs to be</span> 303<span class="hljs-comment">// overwritten using fill(), write(), or other functions that fill the Buffer's</span> 304<span class="hljs-comment">// contents.</span> 305<span class="hljs-keyword">const</span> buf3 = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">allocUnsafe</span>(<span class="hljs-number">10</span>); 306 307<span class="hljs-comment">// Creates a Buffer containing the bytes [1, 2, 3].</span> 308<span class="hljs-keyword">const</span> buf4 = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>([<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-number">3</span>]); 309 310<span class="hljs-comment">// Creates a Buffer containing the bytes [1, 1, 1, 1] – the entries</span> 311<span class="hljs-comment">// are all truncated using `(value & 255)` to fit into the range 0–255.</span> 312<span class="hljs-keyword">const</span> buf5 = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>([<span class="hljs-number">257</span>, <span class="hljs-number">257.5</span>, -<span class="hljs-number">255</span>, <span class="hljs-string">'1'</span>]); 313 314<span class="hljs-comment">// Creates a Buffer containing the UTF-8-encoded bytes for the string 'tést':</span> 315<span class="hljs-comment">// [0x74, 0xc3, 0xa9, 0x73, 0x74] (in hexadecimal notation)</span> 316<span class="hljs-comment">// [116, 195, 169, 115, 116] (in decimal notation)</span> 317<span class="hljs-keyword">const</span> buf6 = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(<span class="hljs-string">'tést'</span>); 318 319<span class="hljs-comment">// Creates a Buffer containing the Latin-1 bytes [0x74, 0xe9, 0x73, 0x74].</span> 320<span class="hljs-keyword">const</span> buf7 = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(<span class="hljs-string">'tést'</span>, <span class="hljs-string">'latin1'</span>);</code></pre> 321<section><h3>Buffers and character encodings<span><a class="mark" href="#buffer_buffers_and_character_encodings" id="buffer_buffers_and_character_encodings">#</a></span></h3> 322<div class="api_metadata"> 323<details class="changelog"><summary>History</summary> 324<table> 325<tbody><tr><th>Version</th><th>Changes</th></tr> 326<tr><td>v14.18.0</td> 327<td><p>Introduced <code>base64url</code> encoding.</p></td></tr> 328<tr><td>v6.4.0</td> 329<td><p>Introduced <code>latin1</code> as an alias for <code>binary</code>.</p></td></tr> 330<tr><td>v5.0.0</td> 331<td><p>Removed the deprecated <code>raw</code> and <code>raws</code> encodings.</p></td></tr> 332</tbody></table> 333</details> 334</div> 335<p>When converting between <code>Buffer</code>s and strings, a character encoding may be 336specified. If no character encoding is specified, UTF-8 will be used as the 337default.</p> 338<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(<span class="hljs-string">'hello world'</span>, <span class="hljs-string">'utf8'</span>); 339 340<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">toString</span>(<span class="hljs-string">'hex'</span>)); 341<span class="hljs-comment">// Prints: 68656c6c6f20776f726c64</span> 342<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">toString</span>(<span class="hljs-string">'base64'</span>)); 343<span class="hljs-comment">// Prints: aGVsbG8gd29ybGQ=</span> 344 345<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(<span class="hljs-string">'fhqwhgads'</span>, <span class="hljs-string">'utf8'</span>)); 346<span class="hljs-comment">// Prints: <Buffer 66 68 71 77 68 67 61 64 73></span> 347<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(<span class="hljs-string">'fhqwhgads'</span>, <span class="hljs-string">'utf16le'</span>)); 348<span class="hljs-comment">// Prints: <Buffer 66 00 68 00 71 00 77 00 68 00 67 00 61 00 64 00 73 00></span></code></pre> 349<p>The character encodings currently supported by Node.js are the following:</p> 350<ul> 351<li> 352<p><code>'utf8'</code>: Multi-byte encoded Unicode characters. Many web pages and other 353document formats use <a href="https://en.wikipedia.org/wiki/UTF-8">UTF-8</a>. This is the default character encoding. 354When decoding a <code>Buffer</code> into a string that does not exclusively contain 355valid UTF-8 data, the Unicode replacement character <code>U+FFFD</code> � will be used 356to represent those errors.</p> 357</li> 358<li> 359<p><code>'utf16le'</code>: Multi-byte encoded Unicode characters. Unlike <code>'utf8'</code>, each 360character in the string will be encoded using either 2 or 4 bytes. 361Node.js only supports the <a href="https://en.wikipedia.org/wiki/Endianness">little-endian</a> variant of <a href="https://en.wikipedia.org/wiki/UTF-16">UTF-16</a>.</p> 362</li> 363<li> 364<p><code>'latin1'</code>: Latin-1 stands for <a href="https://en.wikipedia.org/wiki/ISO-8859-1">ISO-8859-1</a>. This character encoding only 365supports the Unicode characters from <code>U+0000</code> to <code>U+00FF</code>. Each character is 366encoded using a single byte. Characters that do not fit into that range are 367truncated and will be mapped to characters in that range.</p> 368</li> 369</ul> 370<p>Converting a <code>Buffer</code> into a string using one of the above is referred to as 371decoding, and converting a string into a <code>Buffer</code> is referred to as encoding.</p> 372<p>Node.js also supports the following binary-to-text encodings. For 373binary-to-text encodings, the naming convention is reversed: Converting a 374<code>Buffer</code> into a string is typically referred to as encoding, and converting a 375string into a <code>Buffer</code> as decoding.</p> 376<ul> 377<li> 378<p><code>'base64'</code>: <a href="https://en.wikipedia.org/wiki/Base64">Base64</a> encoding. When creating a <code>Buffer</code> from a string, 379this encoding will also correctly accept "URL and Filename Safe Alphabet" as 380specified in <a href="https://tools.ietf.org/html/rfc4648#section-5">RFC 4648, Section 5</a>. Whitespace characters such as spaces, 381tabs, and new lines contained within the base64-encoded string are ignored.</p> 382</li> 383<li> 384<p><code>'base64url'</code>: <a href="https://tools.ietf.org/html/rfc4648#section-5">base64url</a> encoding as specified in 385<a href="https://tools.ietf.org/html/rfc4648#section-5">RFC 4648, Section 5</a>. When creating a <code>Buffer</code> from a string, this 386encoding will also correctly accept regular base64-encoded strings. When 387encoding a <code>Buffer</code> to a string, this encoding will omit padding.</p> 388</li> 389<li> 390<p><code>'hex'</code>: Encode each byte as two hexadecimal characters. Data truncation 391may occur when decoding strings that do exclusively contain valid hexadecimal 392characters. See below for an example.</p> 393</li> 394</ul> 395<p>The following legacy character encodings are also supported:</p> 396<ul> 397<li> 398<p><code>'ascii'</code>: For 7-bit <a href="https://en.wikipedia.org/wiki/ASCII">ASCII</a> data only. When encoding a string into a 399<code>Buffer</code>, this is equivalent to using <code>'latin1'</code>. When decoding a <code>Buffer</code> 400into a string, using this encoding will additionally unset the highest bit of 401each byte before decoding as <code>'latin1'</code>. 402Generally, there should be no reason to use this encoding, as <code>'utf8'</code> 403(or, if the data is known to always be ASCII-only, <code>'latin1'</code>) will be a 404better choice when encoding or decoding ASCII-only text. It is only provided 405for legacy compatibility.</p> 406</li> 407<li> 408<p><code>'binary'</code>: Alias for <code>'latin1'</code>. See <a href="https://developer.mozilla.org/en-US/docs/Web/API/DOMString/Binary">binary strings</a> for more background 409on this topic. The name of this encoding can be very misleading, as all of the 410encodings listed here convert between strings and binary data. For converting 411between strings and <code>Buffer</code>s, typically <code>'utf-8'</code> is the right choice.</p> 412</li> 413<li> 414<p><code>'ucs2'</code>: Alias of <code>'utf16le'</code>. UCS-2 used to refer to a variant of UTF-16 415that did not support characters that had code points larger than U+FFFF. 416In Node.js, these code points are always supported.</p> 417</li> 418</ul> 419<pre><code class="language-js"><span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(<span class="hljs-string">'1ag'</span>, <span class="hljs-string">'hex'</span>); 420<span class="hljs-comment">// Prints <Buffer 1a>, data truncated when first non-hexadecimal value</span> 421<span class="hljs-comment">// ('g') encountered.</span> 422 423<span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(<span class="hljs-string">'1a7g'</span>, <span class="hljs-string">'hex'</span>); 424<span class="hljs-comment">// Prints <Buffer 1a>, data truncated when data ends in single digit ('7').</span> 425 426<span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(<span class="hljs-string">'1634'</span>, <span class="hljs-string">'hex'</span>); 427<span class="hljs-comment">// Prints <Buffer 16 34>, all data represented.</span></code></pre> 428<p>Modern Web browsers follow the <a href="https://encoding.spec.whatwg.org/">WHATWG Encoding Standard</a> which aliases 429both <code>'latin1'</code> and <code>'ISO-8859-1'</code> to <code>'win-1252'</code>. This means that while doing 430something like <code>http.get()</code>, if the returned charset is one of those listed in 431the WHATWG specification it is possible that the server actually returned 432<code>'win-1252'</code>-encoded data, and using <code>'latin1'</code> encoding may incorrectly decode 433the characters.</p> 434</section><section><h3>Buffers and TypedArrays<span><a class="mark" href="#buffer_buffers_and_typedarrays" id="buffer_buffers_and_typedarrays">#</a></span></h3> 435<div class="api_metadata"> 436<details class="changelog"><summary>History</summary> 437<table> 438<tbody><tr><th>Version</th><th>Changes</th></tr> 439<tr><td>v3.0.0</td> 440<td><p>The <code>Buffer</code>s class now inherits from <code>Uint8Array</code>.</p></td></tr> 441</tbody></table> 442</details> 443</div> 444<p><code>Buffer</code> instances are also JavaScript <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Uint8Array"><code>Uint8Array</code></a> and <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray"><code>TypedArray</code></a> 445instances. All <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray"><code>TypedArray</code></a> methods are available on <code>Buffer</code>s. There are, 446however, subtle incompatibilities between the <code>Buffer</code> API and the 447<a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray"><code>TypedArray</code></a> API.</p> 448<p>In particular:</p> 449<ul> 450<li>While <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray/slice"><code>TypedArray.prototype.slice()</code></a> creates a copy of part of the <code>TypedArray</code>, 451<a href="#buffer_buf_slice_start_end"><code>Buffer.prototype.slice()</code></a> creates a view over the existing <code>Buffer</code> 452without copying. This behavior can be surprising, and only exists for legacy 453compatibility. <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray/subarray"><code>TypedArray.prototype.subarray()</code></a> can be used to achieve 454the behavior of <a href="#buffer_buf_slice_start_end"><code>Buffer.prototype.slice()</code></a> on both <code>Buffer</code>s 455and other <code>TypedArray</code>s.</li> 456<li><a href="#buffer_buf_tostring_encoding_start_end"><code>buf.toString()</code></a> is incompatible with its <code>TypedArray</code> equivalent.</li> 457<li>A number of methods, e.g. <a href="#buffer_buf_indexof_value_byteoffset_encoding"><code>buf.indexOf()</code></a>, support additional arguments.</li> 458</ul> 459<p>There are two ways to create new <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray"><code>TypedArray</code></a> instances from a <code>Buffer</code>:</p> 460<ul> 461<li>Passing a <code>Buffer</code> to a <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray"><code>TypedArray</code></a> constructor will copy the <code>Buffer</code>s 462contents, interpreted as an array of integers, and not as a byte sequence 463of the target type.</li> 464</ul> 465<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>([<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-number">3</span>, <span class="hljs-number">4</span>]); 466<span class="hljs-keyword">const</span> uint32array = <span class="hljs-keyword">new</span> <span class="hljs-title class_">Uint</span>32<span class="hljs-built_in">Array</span>(buf); 467 468<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(uint32array); 469 470<span class="hljs-comment">// Prints: Uint32Array(4) [ 1, 2, 3, 4 ]</span></code></pre> 471<ul> 472<li>Passing the <code>Buffer</code>s underlying <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/ArrayBuffer"><code>ArrayBuffer</code></a> will create a 473<a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray"><code>TypedArray</code></a> that shares its memory with the <code>Buffer</code>.</li> 474</ul> 475<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(<span class="hljs-string">'hello'</span>, <span class="hljs-string">'utf16le'</span>); 476<span class="hljs-keyword">const</span> uint16array = <span class="hljs-keyword">new</span> <span class="hljs-title class_">Uint</span>16<span class="hljs-built_in">Array</span>( 477 buf.<span class="hljs-property">buffer</span>, 478 buf.<span class="hljs-property">byteOffset</span>, 479 buf.<span class="hljs-property">length</span> / <span class="hljs-title class_">Uint</span>16<span class="hljs-built_in">Array</span>.<span class="hljs-property">BYTES_PER_ELEMENT</span>); 480 481<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(uint16array); 482 483<span class="hljs-comment">// Prints: Uint16Array(5) [ 104, 101, 108, 108, 111 ]</span></code></pre> 484<p>It is possible to create a new <code>Buffer</code> that shares the same allocated 485memory as a <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray"><code>TypedArray</code></a> instance by using the <code>TypedArray</code> object’s 486<code>.buffer</code> property in the same way. <a href="#buffer_static_method_buffer_from_arraybuffer_byteoffset_length"><code>Buffer.from()</code></a> 487behaves like <code>new Uint8Array()</code> in this context.</p> 488<pre><code class="language-js"><span class="hljs-keyword">const</span> arr = <span class="hljs-keyword">new</span> <span class="hljs-title class_">Uint</span>16<span class="hljs-built_in">Array</span>(<span class="hljs-number">2</span>); 489 490arr[<span class="hljs-number">0</span>] = <span class="hljs-number">5000</span>; 491arr[<span class="hljs-number">1</span>] = <span class="hljs-number">4000</span>; 492 493<span class="hljs-comment">// Copies the contents of `arr`.</span> 494<span class="hljs-keyword">const</span> buf1 = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(arr); 495 496<span class="hljs-comment">// Shares memory with `arr`.</span> 497<span class="hljs-keyword">const</span> buf2 = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(arr.<span class="hljs-property">buffer</span>); 498 499<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf1); 500<span class="hljs-comment">// Prints: <Buffer 88 a0></span> 501<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf2); 502<span class="hljs-comment">// Prints: <Buffer 88 13 a0 0f></span> 503 504arr[<span class="hljs-number">1</span>] = <span class="hljs-number">6000</span>; 505 506<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf1); 507<span class="hljs-comment">// Prints: <Buffer 88 a0></span> 508<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf2); 509<span class="hljs-comment">// Prints: <Buffer 88 13 70 17></span></code></pre> 510<p>When creating a <code>Buffer</code> using a <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray"><code>TypedArray</code></a>'s <code>.buffer</code>, it is 511possible to use only a portion of the underlying <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/ArrayBuffer"><code>ArrayBuffer</code></a> by passing in 512<code>byteOffset</code> and <code>length</code> parameters.</p> 513<pre><code class="language-js"><span class="hljs-keyword">const</span> arr = <span class="hljs-keyword">new</span> <span class="hljs-title class_">Uint</span>16<span class="hljs-built_in">Array</span>(<span class="hljs-number">20</span>); 514<span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(arr.<span class="hljs-property">buffer</span>, <span class="hljs-number">0</span>, <span class="hljs-number">16</span>); 515 516<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-property">length</span>); 517<span class="hljs-comment">// Prints: 16</span></code></pre> 518<p>The <code>Buffer.from()</code> and <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray/from"><code>TypedArray.from()</code></a> have different signatures and 519implementations. Specifically, the <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray"><code>TypedArray</code></a> variants accept a second 520argument that is a mapping function that is invoked on every element of the 521typed array:</p> 522<ul> 523<li><code>TypedArray.from(source[, mapFn[, thisArg]])</code></li> 524</ul> 525<p>The <code>Buffer.from()</code> method, however, does not support the use of a mapping 526function:</p> 527<ul> 528<li><a href="#buffer_static_method_buffer_from_array"><code>Buffer.from(array)</code></a></li> 529<li><a href="#buffer_static_method_buffer_from_buffer"><code>Buffer.from(buffer)</code></a></li> 530<li><a href="#buffer_static_method_buffer_from_arraybuffer_byteoffset_length"><code>Buffer.from(arrayBuffer[, byteOffset[, length]])</code></a></li> 531<li><a href="#buffer_static_method_buffer_from_string_encoding"><code>Buffer.from(string[, encoding])</code></a></li> 532</ul> 533</section><section><h3>Buffers and iteration<span><a class="mark" href="#buffer_buffers_and_iteration" id="buffer_buffers_and_iteration">#</a></span></h3> 534<p><code>Buffer</code> instances can be iterated over using <code>for..of</code> syntax:</p> 535<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>([<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-number">3</span>]); 536 537<span class="hljs-keyword">for</span> (<span class="hljs-keyword">const</span> b <span class="hljs-keyword">of</span> buf) { 538 <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(b); 539} 540<span class="hljs-comment">// Prints:</span> 541<span class="hljs-comment">// 1</span> 542<span class="hljs-comment">// 2</span> 543<span class="hljs-comment">// 3</span></code></pre> 544<p>Additionally, the <a href="#buffer_buf_values"><code>buf.values()</code></a>, <a href="#buffer_buf_keys"><code>buf.keys()</code></a>, and 545<a href="#buffer_buf_entries"><code>buf.entries()</code></a> methods can be used to create iterators.</p> 546</section><section><h3>Class: <code>Blob</code><span><a class="mark" href="#buffer_class_blob" id="buffer_class_blob">#</a></span></h3> 547<div class="api_metadata"> 548<span>Added in: v14.18.0</span> 549</div> 550<p></p><div class="api_stability api_stability_1"><a href="documentation.html#documentation_stability_index">Stability: 1</a> - Experimental</div><p></p> 551<p>A <a href="https://developer.mozilla.org/en-US/docs/Web/API/Blob"><code>Blob</code></a> encapsulates immutable, raw data that can be safely shared across 552multiple worker threads.</p> 553<h4><code>new buffer.Blob([sources[, options]])</code><span><a class="mark" href="#buffer_new_buffer_blob_sources_options" id="buffer_new_buffer_blob_sources_options">#</a></span></h4> 554<div class="api_metadata"> 555<span>Added in: v14.18.0</span> 556</div> 557<ul> 558<li><code>sources</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string[]></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/ArrayBuffer" class="type"><ArrayBuffer[]></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type"><TypedArray[]></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type"><DataView[]></a> | <a href="buffer.html#buffer_class_blob" class="type"><Blob[]></a> An array 559of string, <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/ArrayBuffer" class="type"><ArrayBuffer></a>, <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type"><TypedArray></a>, <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type"><DataView></a>, or <a href="buffer.html#buffer_class_blob" class="type"><Blob></a> objects, or 560any mix of such objects, that will be stored within the <code>Blob</code>.</li> 561<li><code>options</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a> 562<ul> 563<li><code>encoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> The character encoding to use for string sources. 564<strong>Default</strong>: <code>'utf8'</code>.</li> 565<li><code>type</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> The Blob content-type. The intent is for <code>type</code> to convey 566the MIME media type of the data, however no validation of the type format 567is performed.</li> 568</ul> 569</li> 570</ul> 571<p>Creates a new <code>Blob</code> object containing a concatenation of the given sources.</p> 572<p><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/ArrayBuffer" class="type"><ArrayBuffer></a>, <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type"><TypedArray></a>, <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type"><DataView></a>, and <a href="buffer.html#buffer_class_buffer" class="type"><Buffer></a> sources are copied into 573the 'Blob' and can therefore be safely modified after the 'Blob' is created.</p> 574<p>String sources are also copied into the <code>Blob</code>.</p> 575<h4><code>blob.arrayBuffer()</code><span><a class="mark" href="#buffer_blob_arraybuffer" id="buffer_blob_arraybuffer">#</a></span></h4> 576<div class="api_metadata"> 577<span>Added in: v14.18.0</span> 578</div> 579<ul> 580<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise" class="type"><Promise></a></li> 581</ul> 582<p>Returns a promise that fulfills with an <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/ArrayBuffer" class="type"><ArrayBuffer></a> containing a copy of 583the <code>Blob</code> data.</p> 584<h4><code>blob.size</code><span><a class="mark" href="#buffer_blob_size" id="buffer_blob_size">#</a></span></h4> 585<div class="api_metadata"> 586<span>Added in: v14.18.0</span> 587</div> 588<p>The total size of the <code>Blob</code> in bytes.</p> 589<h4><code>blob.slice([start, [end, [type]]])</code><span><a class="mark" href="#buffer_blob_slice_start_end_type" id="buffer_blob_slice_start_end_type">#</a></span></h4> 590<div class="api_metadata"> 591<span>Added in: v14.18.0</span> 592</div> 593<ul> 594<li><code>start</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><number></a> The starting index.</li> 595<li><code>end</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><number></a> The ending index.</li> 596<li><code>type</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> The content-type for the new <code>Blob</code></li> 597</ul> 598<p>Creates and returns a new <code>Blob</code> containing a subset of this <code>Blob</code> objects 599data. The original <code>Blob</code> is not alterered.</p> 600<h4><code>blob.text()</code><span><a class="mark" href="#buffer_blob_text" id="buffer_blob_text">#</a></span></h4> 601<div class="api_metadata"> 602<span>Added in: v14.18.0</span> 603</div> 604<ul> 605<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise" class="type"><Promise></a></li> 606</ul> 607<p>Returns a promise that resolves the contents of the <code>Blob</code> decoded as a UTF-8 608string.</p> 609<h4><code>blob.type</code><span><a class="mark" href="#buffer_blob_type" id="buffer_blob_type">#</a></span></h4> 610<div class="api_metadata"> 611<span>Added in: v14.18.0</span> 612</div> 613<ul> 614<li>Type: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a></li> 615</ul> 616<p>The content-type of the <code>Blob</code>.</p> 617<h4><code>Blob</code> objects and <code>MessageChannel</code><span><a class="mark" href="#buffer_blob_objects_and_messagechannel" id="buffer_blob_objects_and_messagechannel">#</a></span></h4> 618<p>Once a <a href="buffer.html#buffer_class_blob" class="type"><Blob></a> object is created, it can be sent via <code>MessagePort</code> to multiple 619destinations without transfering or immediately copying the data. The data 620contained by the <code>Blob</code> is copied only when the <code>arrayBuffer()</code> or <code>text()</code> 621methods are called.</p> 622<pre><code class="language-js"><span class="hljs-keyword">const</span> { <span class="hljs-title class_">Blob</span> } = <span class="hljs-built_in">require</span>(<span class="hljs-string">'buffer'</span>); 623<span class="hljs-keyword">const</span> blob = <span class="hljs-keyword">new</span> <span class="hljs-title class_">Blob</span>([<span class="hljs-string">'hello there'</span>]); 624<span class="hljs-keyword">const</span> { <span class="hljs-attr">setTimeout</span>: delay } = <span class="hljs-built_in">require</span>(<span class="hljs-string">'timers/promises'</span>); 625 626<span class="hljs-keyword">const</span> mc1 = <span class="hljs-keyword">new</span> <span class="hljs-title class_">MessageChannel</span>(); 627<span class="hljs-keyword">const</span> mc2 = <span class="hljs-keyword">new</span> <span class="hljs-title class_">MessageChannel</span>(); 628 629mc1.<span class="hljs-property">port1</span>.<span class="hljs-property">onmessage</span> = <span class="hljs-keyword">async</span> ({ data }) => { 630 <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-keyword">await</span> data.<span class="hljs-title function_">arrayBuffer</span>()); 631 mc1.<span class="hljs-property">port1</span>.<span class="hljs-title function_">close</span>(); 632}; 633 634mc2.<span class="hljs-property">port1</span>.<span class="hljs-property">onmessage</span> = <span class="hljs-keyword">async</span> ({ data }) => { 635 <span class="hljs-keyword">await</span> <span class="hljs-title function_">delay</span>(<span class="hljs-number">1000</span>); 636 <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-keyword">await</span> data.<span class="hljs-title function_">arrayBuffer</span>()); 637 mc2.<span class="hljs-property">port1</span>.<span class="hljs-title function_">close</span>(); 638}; 639 640mc1.<span class="hljs-property">port2</span>.<span class="hljs-title function_">postMessage</span>(blob); 641mc2.<span class="hljs-property">port2</span>.<span class="hljs-title function_">postMessage</span>(blob); 642 643<span class="hljs-comment">// The Blob is still usable after posting.</span> 644data.<span class="hljs-title function_">text</span>().<span class="hljs-title function_">then</span>(<span class="hljs-variable language_">console</span>.<span class="hljs-property">log</span>);</code></pre> 645</section><section><h3>Class: <code>Buffer</code><span><a class="mark" href="#buffer_class_buffer" id="buffer_class_buffer">#</a></span></h3> 646<p>The <code>Buffer</code> class is a global type for dealing with binary data directly. 647It can be constructed in a variety of ways.</p> 648<h4>Static method: <code>Buffer.alloc(size[, fill[, encoding]])</code><span><a class="mark" href="#buffer_static_method_buffer_alloc_size_fill_encoding" id="buffer_static_method_buffer_alloc_size_fill_encoding">#</a></span></h4> 649<div class="api_metadata"> 650<details class="changelog"><summary>History</summary> 651<table> 652<tbody><tr><th>Version</th><th>Changes</th></tr> 653<tr><td>v10.0.0</td> 654<td><p>Attempting to fill a non-zero length buffer with a zero length buffer triggers a thrown exception.</p></td></tr> 655<tr><td>v10.0.0</td> 656<td><p>Specifying an invalid string for <code>fill</code> triggers a thrown exception.</p></td></tr> 657<tr><td>v8.9.3</td> 658<td><p>Specifying an invalid string for <code>fill</code> now results in a zero-filled buffer.</p></td></tr> 659<tr><td>v5.10.0</td> 660<td><p><span>Added in: v5.10.0</span></p></td></tr> 661</tbody></table> 662</details> 663</div> 664<ul> 665<li><code>size</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> The desired length of the new <code>Buffer</code>.</li> 666<li><code>fill</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> | <a href="buffer.html#buffer_class_buffer" class="type"><Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Uint8Array" class="type"><Uint8Array></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> A value to pre-fill the new <code>Buffer</code> 667with. <strong>Default:</strong> <code>0</code>.</li> 668<li><code>encoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> If <code>fill</code> is a string, this is its encoding. 669<strong>Default:</strong> <code>'utf8'</code>.</li> 670</ul> 671<p>Allocates a new <code>Buffer</code> of <code>size</code> bytes. If <code>fill</code> is <code>undefined</code>, the 672<code>Buffer</code> will be zero-filled.</p> 673<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">alloc</span>(<span class="hljs-number">5</span>); 674 675<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf); 676<span class="hljs-comment">// Prints: <Buffer 00 00 00 00 00></span></code></pre> 677<p>If <code>size</code> is larger than 678<a href="#buffer_buffer_constants_max_length"><code>buffer.constants.MAX_LENGTH</code></a> or smaller than 0, <a href="errors.html#ERR_INVALID_OPT_VALUE"><code>ERR_INVALID_OPT_VALUE</code></a> 679is thrown.</p> 680<p>If <code>fill</code> is specified, the allocated <code>Buffer</code> will be initialized by calling 681<a href="#buffer_buf_fill_value_offset_end_encoding"><code>buf.fill(fill)</code></a>.</p> 682<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">alloc</span>(<span class="hljs-number">5</span>, <span class="hljs-string">'a'</span>); 683 684<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf); 685<span class="hljs-comment">// Prints: <Buffer 61 61 61 61 61></span></code></pre> 686<p>If both <code>fill</code> and <code>encoding</code> are specified, the allocated <code>Buffer</code> will be 687initialized by calling <a href="#buffer_buf_fill_value_offset_end_encoding"><code>buf.fill(fill, encoding)</code></a>.</p> 688<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">alloc</span>(<span class="hljs-number">11</span>, <span class="hljs-string">'aGVsbG8gd29ybGQ='</span>, <span class="hljs-string">'base64'</span>); 689 690<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf); 691<span class="hljs-comment">// Prints: <Buffer 68 65 6c 6c 6f 20 77 6f 72 6c 64></span></code></pre> 692<p>Calling <a href="#buffer_static_method_buffer_alloc_size_fill_encoding"><code>Buffer.alloc()</code></a> can be measurably slower than the alternative 693<a href="#buffer_static_method_buffer_allocunsafe_size"><code>Buffer.allocUnsafe()</code></a> but ensures that the newly created <code>Buffer</code> instance 694contents will never contain sensitive data from previous allocations, including 695data that might not have been allocated for <code>Buffer</code>s.</p> 696<p>A <code>TypeError</code> will be thrown if <code>size</code> is not a number.</p> 697<h4>Static method: <code>Buffer.allocUnsafe(size)</code><span><a class="mark" href="#buffer_static_method_buffer_allocunsafe_size" id="buffer_static_method_buffer_allocunsafe_size">#</a></span></h4> 698<div class="api_metadata"> 699<details class="changelog"><summary>History</summary> 700<table> 701<tbody><tr><th>Version</th><th>Changes</th></tr> 702<tr><td>v7.0.0</td> 703<td><p>Passing a negative <code>size</code> will now throw an error.</p></td></tr> 704<tr><td>v5.10.0</td> 705<td><p><span>Added in: v5.10.0</span></p></td></tr> 706</tbody></table> 707</details> 708</div> 709<ul> 710<li><code>size</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> The desired length of the new <code>Buffer</code>.</li> 711</ul> 712<p>Allocates a new <code>Buffer</code> of <code>size</code> bytes. If <code>size</code> is larger than 713<a href="#buffer_buffer_constants_max_length"><code>buffer.constants.MAX_LENGTH</code></a> or smaller than 0, <a href="errors.html#ERR_INVALID_OPT_VALUE"><code>ERR_INVALID_OPT_VALUE</code></a> 714is thrown.</p> 715<p>The underlying memory for <code>Buffer</code> instances created in this way is <em>not 716initialized</em>. The contents of the newly created <code>Buffer</code> are unknown and 717<em>may contain sensitive data</em>. Use <a href="#buffer_static_method_buffer_alloc_size_fill_encoding"><code>Buffer.alloc()</code></a> instead to initialize 718<code>Buffer</code> instances with zeroes.</p> 719<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">allocUnsafe</span>(<span class="hljs-number">10</span>); 720 721<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf); 722<span class="hljs-comment">// Prints (contents may vary): <Buffer a0 8b 28 3f 01 00 00 00 50 32></span> 723 724buf.<span class="hljs-title function_">fill</span>(<span class="hljs-number">0</span>); 725 726<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf); 727<span class="hljs-comment">// Prints: <Buffer 00 00 00 00 00 00 00 00 00 00></span></code></pre> 728<p>A <code>TypeError</code> will be thrown if <code>size</code> is not a number.</p> 729<p>The <code>Buffer</code> module pre-allocates an internal <code>Buffer</code> instance of 730size <a href="#buffer_class_property_buffer_poolsize"><code>Buffer.poolSize</code></a> that is used as a pool for the fast allocation of new 731<code>Buffer</code> instances created using <a href="#buffer_static_method_buffer_allocunsafe_size"><code>Buffer.allocUnsafe()</code></a>, 732<a href="#buffer_static_method_buffer_from_array"><code>Buffer.from(array)</code></a>, <a href="#buffer_static_method_buffer_concat_list_totallength"><code>Buffer.concat()</code></a>, and the deprecated 733<code>new Buffer(size)</code> constructor only when <code>size</code> is less than or equal 734to <code>Buffer.poolSize >> 1</code> (floor of <a href="#buffer_class_property_buffer_poolsize"><code>Buffer.poolSize</code></a> divided by two).</p> 735<p>Use of this pre-allocated internal memory pool is a key difference between 736calling <code>Buffer.alloc(size, fill)</code> vs. <code>Buffer.allocUnsafe(size).fill(fill)</code>. 737Specifically, <code>Buffer.alloc(size, fill)</code> will <em>never</em> use the internal <code>Buffer</code> 738pool, while <code>Buffer.allocUnsafe(size).fill(fill)</code> <em>will</em> use the internal 739<code>Buffer</code> pool if <code>size</code> is less than or equal to half <a href="#buffer_class_property_buffer_poolsize"><code>Buffer.poolSize</code></a>. The 740difference is subtle but can be important when an application requires the 741additional performance that <a href="#buffer_static_method_buffer_allocunsafe_size"><code>Buffer.allocUnsafe()</code></a> provides.</p> 742<h4>Static method: <code>Buffer.allocUnsafeSlow(size)</code><span><a class="mark" href="#buffer_static_method_buffer_allocunsafeslow_size" id="buffer_static_method_buffer_allocunsafeslow_size">#</a></span></h4> 743<div class="api_metadata"> 744<span>Added in: v5.12.0</span> 745</div> 746<ul> 747<li><code>size</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> The desired length of the new <code>Buffer</code>.</li> 748</ul> 749<p>Allocates a new <code>Buffer</code> of <code>size</code> bytes. If <code>size</code> is larger than 750<a href="#buffer_buffer_constants_max_length"><code>buffer.constants.MAX_LENGTH</code></a> or smaller than 0, <a href="errors.html#ERR_INVALID_OPT_VALUE"><code>ERR_INVALID_OPT_VALUE</code></a> 751is thrown. A zero-length <code>Buffer</code> is created if <code>size</code> is 0.</p> 752<p>The underlying memory for <code>Buffer</code> instances created in this way is <em>not 753initialized</em>. The contents of the newly created <code>Buffer</code> are unknown and 754<em>may contain sensitive data</em>. Use <a href="#buffer_buf_fill_value_offset_end_encoding"><code>buf.fill(0)</code></a> to initialize 755such <code>Buffer</code> instances with zeroes.</p> 756<p>When using <a href="#buffer_static_method_buffer_allocunsafe_size"><code>Buffer.allocUnsafe()</code></a> to allocate new <code>Buffer</code> instances, 757allocations under 4KB are sliced from a single pre-allocated <code>Buffer</code>. This 758allows applications to avoid the garbage collection overhead of creating many 759individually allocated <code>Buffer</code> instances. This approach improves both 760performance and memory usage by eliminating the need to track and clean up as 761many individual <code>ArrayBuffer</code> objects.</p> 762<p>However, in the case where a developer may need to retain a small chunk of 763memory from a pool for an indeterminate amount of time, it may be appropriate 764to create an un-pooled <code>Buffer</code> instance using <code>Buffer.allocUnsafeSlow()</code> and 765then copying out the relevant bits.</p> 766<pre><code class="language-js"><span class="hljs-comment">// Need to keep around a few small chunks of memory.</span> 767<span class="hljs-keyword">const</span> store = []; 768 769socket.<span class="hljs-title function_">on</span>(<span class="hljs-string">'readable'</span>, <span class="hljs-function">() =></span> { 770 <span class="hljs-keyword">let</span> data; 771 <span class="hljs-keyword">while</span> (<span class="hljs-literal">null</span> !== (data = readable.<span class="hljs-title function_">read</span>())) { 772 <span class="hljs-comment">// Allocate for retained data.</span> 773 <span class="hljs-keyword">const</span> sb = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">allocUnsafeSlow</span>(<span class="hljs-number">10</span>); 774 775 <span class="hljs-comment">// Copy the data into the new allocation.</span> 776 data.<span class="hljs-title function_">copy</span>(sb, <span class="hljs-number">0</span>, <span class="hljs-number">0</span>, <span class="hljs-number">10</span>); 777 778 store.<span class="hljs-title function_">push</span>(sb); 779 } 780});</code></pre> 781<p>A <code>TypeError</code> will be thrown if <code>size</code> is not a number.</p> 782<h4>Static method: <code>Buffer.byteLength(string[, encoding])</code><span><a class="mark" href="#buffer_static_method_buffer_bytelength_string_encoding" id="buffer_static_method_buffer_bytelength_string_encoding">#</a></span></h4> 783<div class="api_metadata"> 784<details class="changelog"><summary>History</summary> 785<table> 786<tbody><tr><th>Version</th><th>Changes</th></tr> 787<tr><td>v7.0.0</td> 788<td><p>Passing invalid input will now throw an error.</p></td></tr> 789<tr><td>v5.10.0</td> 790<td><p>The <code>string</code> parameter can now be any <code>TypedArray</code>, <code>DataView</code> or <code>ArrayBuffer</code>.</p></td></tr> 791<tr><td>v0.1.90</td> 792<td><p><span>Added in: v0.1.90</span></p></td></tr> 793</tbody></table> 794</details> 795</div> 796<ul> 797<li><code>string</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> | <a href="buffer.html#buffer_class_buffer" class="type"><Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type"><TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type"><DataView></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/ArrayBuffer" class="type"><ArrayBuffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/SharedArrayBuffer" class="type"><SharedArrayBuffer></a> A 798value to calculate the length of.</li> 799<li><code>encoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> If <code>string</code> is a string, this is its encoding. 800<strong>Default:</strong> <code>'utf8'</code>.</li> 801<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> The number of bytes contained within <code>string</code>.</li> 802</ul> 803<p>Returns the byte length of a string when encoded using <code>encoding</code>. 804This is not the same as <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/length"><code>String.prototype.length</code></a>, which does not account 805for the encoding that is used to convert the string into bytes.</p> 806<p>For <code>'base64'</code>, <code>'base64url'</code>, and <code>'hex'</code>, this function assumes valid input. 807For strings that contain non-base64/hex-encoded data (e.g. whitespace), the 808return value might be greater than the length of a <code>Buffer</code> created from the 809string.</p> 810<pre><code class="language-js"><span class="hljs-keyword">const</span> str = <span class="hljs-string">'\u00bd + \u00bc = \u00be'</span>; 811 812<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-string">`<span class="hljs-subst">${str}</span>: <span class="hljs-subst">${str.length}</span> characters, `</span> + 813 <span class="hljs-string">`<span class="hljs-subst">${Buffer.byteLength(str, <span class="hljs-string">'utf8'</span>)}</span> bytes`</span>); 814<span class="hljs-comment">// Prints: ½ + ¼ = ¾: 9 characters, 12 bytes</span></code></pre> 815<p>When <code>string</code> is a <code>Buffer</code>/<a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView"><code>DataView</code></a>/<a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray"><code>TypedArray</code></a>/<a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/ArrayBuffer"><code>ArrayBuffer</code></a>/ 816<a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/SharedArrayBuffer"><code>SharedArrayBuffer</code></a>, the byte length as reported by <code>.byteLength</code> 817is returned.</p> 818<h4>Static method: <code>Buffer.compare(buf1, buf2)</code><span><a class="mark" href="#buffer_static_method_buffer_compare_buf1_buf2" id="buffer_static_method_buffer_compare_buf1_buf2">#</a></span></h4> 819<div class="api_metadata"> 820<details class="changelog"><summary>History</summary> 821<table> 822<tbody><tr><th>Version</th><th>Changes</th></tr> 823<tr><td>v8.0.0</td> 824<td><p>The arguments can now be <code>Uint8Array</code>s.</p></td></tr> 825<tr><td>v0.11.13</td> 826<td><p><span>Added in: v0.11.13</span></p></td></tr> 827</tbody></table> 828</details> 829</div> 830<ul> 831<li><code>buf1</code> <a href="buffer.html#buffer_class_buffer" class="type"><Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Uint8Array" class="type"><Uint8Array></a></li> 832<li><code>buf2</code> <a href="buffer.html#buffer_class_buffer" class="type"><Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Uint8Array" class="type"><Uint8Array></a></li> 833<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Either <code>-1</code>, <code>0</code>, or <code>1</code>, depending on the result of the 834comparison. See <a href="#buffer_buf_compare_target_targetstart_targetend_sourcestart_sourceend"><code>buf.compare()</code></a> for details.</li> 835</ul> 836<p>Compares <code>buf1</code> to <code>buf2</code>, typically for the purpose of sorting arrays of 837<code>Buffer</code> instances. This is equivalent to calling 838<a href="#buffer_buf_compare_target_targetstart_targetend_sourcestart_sourceend"><code>buf1.compare(buf2)</code></a>.</p> 839<pre><code class="language-js"><span class="hljs-keyword">const</span> buf1 = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(<span class="hljs-string">'1234'</span>); 840<span class="hljs-keyword">const</span> buf2 = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(<span class="hljs-string">'0123'</span>); 841<span class="hljs-keyword">const</span> arr = [buf1, buf2]; 842 843<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(arr.<span class="hljs-title function_">sort</span>(<span class="hljs-title class_">Buffer</span>.<span class="hljs-property">compare</span>)); 844<span class="hljs-comment">// Prints: [ <Buffer 30 31 32 33>, <Buffer 31 32 33 34> ]</span> 845<span class="hljs-comment">// (This result is equal to: [buf2, buf1].)</span></code></pre> 846<h4>Static method: <code>Buffer.concat(list[, totalLength])</code><span><a class="mark" href="#buffer_static_method_buffer_concat_list_totallength" id="buffer_static_method_buffer_concat_list_totallength">#</a></span></h4> 847<div class="api_metadata"> 848<details class="changelog"><summary>History</summary> 849<table> 850<tbody><tr><th>Version</th><th>Changes</th></tr> 851<tr><td>v8.0.0</td> 852<td><p>The elements of <code>list</code> can now be <code>Uint8Array</code>s.</p></td></tr> 853<tr><td>v0.7.11</td> 854<td><p><span>Added in: v0.7.11</span></p></td></tr> 855</tbody></table> 856</details> 857</div> 858<ul> 859<li><code>list</code> <a href="buffer.html#buffer_class_buffer" class="type"><Buffer[]></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Uint8Array" class="type"><Uint8Array[]></a> List of <code>Buffer</code> or <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Uint8Array"><code>Uint8Array</code></a> 860instances to concatenate.</li> 861<li><code>totalLength</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Total length of the <code>Buffer</code> instances in <code>list</code> 862when concatenated.</li> 863<li>Returns: <a href="buffer.html#buffer_class_buffer" class="type"><Buffer></a></li> 864</ul> 865<p>Returns a new <code>Buffer</code> which is the result of concatenating all the <code>Buffer</code> 866instances in the <code>list</code> together.</p> 867<p>If the list has no items, or if the <code>totalLength</code> is 0, then a new zero-length 868<code>Buffer</code> is returned.</p> 869<p>If <code>totalLength</code> is not provided, it is calculated from the <code>Buffer</code> instances 870in <code>list</code> by adding their lengths.</p> 871<p>If <code>totalLength</code> is provided, it is coerced to an unsigned integer. If the 872combined length of the <code>Buffer</code>s in <code>list</code> exceeds <code>totalLength</code>, the result is 873truncated to <code>totalLength</code>.</p> 874<pre><code class="language-js"><span class="hljs-comment">// Create a single `Buffer` from a list of three `Buffer` instances.</span> 875 876<span class="hljs-keyword">const</span> buf1 = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">alloc</span>(<span class="hljs-number">10</span>); 877<span class="hljs-keyword">const</span> buf2 = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">alloc</span>(<span class="hljs-number">14</span>); 878<span class="hljs-keyword">const</span> buf3 = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">alloc</span>(<span class="hljs-number">18</span>); 879<span class="hljs-keyword">const</span> totalLength = buf1.<span class="hljs-property">length</span> + buf2.<span class="hljs-property">length</span> + buf3.<span class="hljs-property">length</span>; 880 881<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(totalLength); 882<span class="hljs-comment">// Prints: 42</span> 883 884<span class="hljs-keyword">const</span> bufA = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">concat</span>([buf1, buf2, buf3], totalLength); 885 886<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(bufA); 887<span class="hljs-comment">// Prints: <Buffer 00 00 00 00 ...></span> 888<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(bufA.<span class="hljs-property">length</span>); 889<span class="hljs-comment">// Prints: 42</span></code></pre> 890<p><code>Buffer.concat()</code> may also use the internal <code>Buffer</code> pool like 891<a href="#buffer_static_method_buffer_allocunsafe_size"><code>Buffer.allocUnsafe()</code></a> does.</p> 892<h4>Static method: <code>Buffer.from(array)</code><span><a class="mark" href="#buffer_static_method_buffer_from_array" id="buffer_static_method_buffer_from_array">#</a></span></h4> 893<div class="api_metadata"> 894<span>Added in: v5.10.0</span> 895</div> 896<ul> 897<li><code>array</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer[]></a></li> 898</ul> 899<p>Allocates a new <code>Buffer</code> using an <code>array</code> of bytes in the range <code>0</code> – <code>255</code>. 900Array entries outside that range will be truncated to fit into it.</p> 901<pre><code class="language-js"><span class="hljs-comment">// Creates a new Buffer containing the UTF-8 bytes of the string 'buffer'.</span> 902<span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>([<span class="hljs-number">0x62</span>, <span class="hljs-number">0x75</span>, <span class="hljs-number">0x66</span>, <span class="hljs-number">0x66</span>, <span class="hljs-number">0x65</span>, <span class="hljs-number">0x72</span>]);</code></pre> 903<p>A <code>TypeError</code> will be thrown if <code>array</code> is not an <code>Array</code> or another type 904appropriate for <code>Buffer.from()</code> variants.</p> 905<p><code>Buffer.from(array)</code> and <a href="#buffer_static_method_buffer_from_string_encoding"><code>Buffer.from(string)</code></a> may also use the internal 906<code>Buffer</code> pool like <a href="#buffer_static_method_buffer_allocunsafe_size"><code>Buffer.allocUnsafe()</code></a> does.</p> 907<h4>Static method: <code>Buffer.from(arrayBuffer[, byteOffset[, length]])</code><span><a class="mark" href="#buffer_static_method_buffer_from_arraybuffer_byteoffset_length" id="buffer_static_method_buffer_from_arraybuffer_byteoffset_length">#</a></span></h4> 908<div class="api_metadata"> 909<span>Added in: v5.10.0</span> 910</div> 911<ul> 912<li><code>arrayBuffer</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/ArrayBuffer" class="type"><ArrayBuffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/SharedArrayBuffer" class="type"><SharedArrayBuffer></a> An <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/ArrayBuffer"><code>ArrayBuffer</code></a>, 913<a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/SharedArrayBuffer"><code>SharedArrayBuffer</code></a>, for example the <code>.buffer</code> property of a 914<a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray"><code>TypedArray</code></a>.</li> 915<li><code>byteOffset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Index of first byte to expose. <strong>Default:</strong> <code>0</code>.</li> 916<li><code>length</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to expose. 917<strong>Default:</strong> <code>arrayBuffer.byteLength - byteOffset</code>.</li> 918</ul> 919<p>This creates a view of the <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/ArrayBuffer"><code>ArrayBuffer</code></a> without copying the underlying 920memory. For example, when passed a reference to the <code>.buffer</code> property of a 921<a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray"><code>TypedArray</code></a> instance, the newly created <code>Buffer</code> will share the same 922allocated memory as the <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray"><code>TypedArray</code></a>'s underlying <code>ArrayBuffer</code>.</p> 923<pre><code class="language-js"><span class="hljs-keyword">const</span> arr = <span class="hljs-keyword">new</span> <span class="hljs-title class_">Uint</span>16<span class="hljs-built_in">Array</span>(<span class="hljs-number">2</span>); 924 925arr[<span class="hljs-number">0</span>] = <span class="hljs-number">5000</span>; 926arr[<span class="hljs-number">1</span>] = <span class="hljs-number">4000</span>; 927 928<span class="hljs-comment">// Shares memory with `arr`.</span> 929<span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(arr.<span class="hljs-property">buffer</span>); 930 931<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf); 932<span class="hljs-comment">// Prints: <Buffer 88 13 a0 0f></span> 933 934<span class="hljs-comment">// Changing the original Uint16Array changes the Buffer also.</span> 935arr[<span class="hljs-number">1</span>] = <span class="hljs-number">6000</span>; 936 937<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf); 938<span class="hljs-comment">// Prints: <Buffer 88 13 70 17></span></code></pre> 939<p>The optional <code>byteOffset</code> and <code>length</code> arguments specify a memory range within 940the <code>arrayBuffer</code> that will be shared by the <code>Buffer</code>.</p> 941<pre><code class="language-js"><span class="hljs-keyword">const</span> ab = <span class="hljs-keyword">new</span> <span class="hljs-title class_">ArrayBuffer</span>(<span class="hljs-number">10</span>); 942<span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(ab, <span class="hljs-number">0</span>, <span class="hljs-number">2</span>); 943 944<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-property">length</span>); 945<span class="hljs-comment">// Prints: 2</span></code></pre> 946<p>A <code>TypeError</code> will be thrown if <code>arrayBuffer</code> is not an <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/ArrayBuffer"><code>ArrayBuffer</code></a> or a 947<a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/SharedArrayBuffer"><code>SharedArrayBuffer</code></a> or another type appropriate for <code>Buffer.from()</code> 948variants.</p> 949<p>It is important to remember that a backing <code>ArrayBuffer</code> can cover a range 950of memory that extends beyond the bounds of a <code>TypedArray</code> view. A new 951<code>Buffer</code> created using the <code>buffer</code> property of a <code>TypedArray</code> may extend 952beyond the range of the <code>TypedArray</code>:</p> 953<pre><code class="language-js"><span class="hljs-keyword">const</span> arrA = <span class="hljs-title class_">Uint</span>8<span class="hljs-built_in">Array</span>.<span class="hljs-title function_">from</span>([<span class="hljs-number">0x63</span>, <span class="hljs-number">0x64</span>, <span class="hljs-number">0x65</span>, <span class="hljs-number">0x66</span>]); <span class="hljs-comment">// 4 elements</span> 954<span class="hljs-keyword">const</span> arrB = <span class="hljs-keyword">new</span> <span class="hljs-title class_">Uint</span>8<span class="hljs-built_in">Array</span>(arrA.<span class="hljs-property">buffer</span>, <span class="hljs-number">1</span>, <span class="hljs-number">2</span>); <span class="hljs-comment">// 2 elements</span> 955<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(arrA.<span class="hljs-property">buffer</span> === arrB.<span class="hljs-property">buffer</span>); <span class="hljs-comment">// true</span> 956 957<span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(arrB.<span class="hljs-property">buffer</span>); 958<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf); 959<span class="hljs-comment">// Prints: <Buffer 63 64 65 66></span></code></pre> 960<h4>Static method: <code>Buffer.from(buffer)</code><span><a class="mark" href="#buffer_static_method_buffer_from_buffer" id="buffer_static_method_buffer_from_buffer">#</a></span></h4> 961<div class="api_metadata"> 962<span>Added in: v5.10.0</span> 963</div> 964<ul> 965<li><code>buffer</code> <a href="buffer.html#buffer_class_buffer" class="type"><Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Uint8Array" class="type"><Uint8Array></a> An existing <code>Buffer</code> or <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Uint8Array"><code>Uint8Array</code></a> from 966which to copy data.</li> 967</ul> 968<p>Copies the passed <code>buffer</code> data onto a new <code>Buffer</code> instance.</p> 969<pre><code class="language-js"><span class="hljs-keyword">const</span> buf1 = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(<span class="hljs-string">'buffer'</span>); 970<span class="hljs-keyword">const</span> buf2 = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(buf1); 971 972buf1[<span class="hljs-number">0</span>] = <span class="hljs-number">0x61</span>; 973 974<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf1.<span class="hljs-title function_">toString</span>()); 975<span class="hljs-comment">// Prints: auffer</span> 976<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf2.<span class="hljs-title function_">toString</span>()); 977<span class="hljs-comment">// Prints: buffer</span></code></pre> 978<p>A <code>TypeError</code> will be thrown if <code>buffer</code> is not a <code>Buffer</code> or another type 979appropriate for <code>Buffer.from()</code> variants.</p> 980<h4>Static method: <code>Buffer.from(object[, offsetOrEncoding[, length]])</code><span><a class="mark" href="#buffer_static_method_buffer_from_object_offsetorencoding_length" id="buffer_static_method_buffer_from_object_offsetorencoding_length">#</a></span></h4> 981<div class="api_metadata"> 982<span>Added in: v8.2.0</span> 983</div> 984<ul> 985<li><code>object</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a> An object supporting <code>Symbol.toPrimitive</code> or <code>valueOf()</code>.</li> 986<li><code>offsetOrEncoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> A byte-offset or encoding.</li> 987<li><code>length</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> A length.</li> 988</ul> 989<p>For objects whose <code>valueOf()</code> function returns a value not strictly equal to 990<code>object</code>, returns <code>Buffer.from(object.valueOf(), offsetOrEncoding, length)</code>.</p> 991<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(<span class="hljs-keyword">new</span> <span class="hljs-title class_">String</span>(<span class="hljs-string">'this is a test'</span>)); 992<span class="hljs-comment">// Prints: <Buffer 74 68 69 73 20 69 73 20 61 20 74 65 73 74></span></code></pre> 993<p>For objects that support <code>Symbol.toPrimitive</code>, returns 994<code>Buffer.from(object[Symbol.toPrimitive]('string'), offsetOrEncoding)</code>.</p> 995<pre><code class="language-js"><span class="hljs-keyword">class</span> <span class="hljs-title class_">Foo</span> { 996 [<span class="hljs-title class_">Symbol</span>.<span class="hljs-property">toPrimitive</span>]() { 997 <span class="hljs-keyword">return</span> <span class="hljs-string">'this is a test'</span>; 998 } 999} 1000 1001<span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(<span class="hljs-keyword">new</span> <span class="hljs-title class_">Foo</span>(), <span class="hljs-string">'utf8'</span>); 1002<span class="hljs-comment">// Prints: <Buffer 74 68 69 73 20 69 73 20 61 20 74 65 73 74></span></code></pre> 1003<p>A <code>TypeError</code> will be thrown if <code>object</code> does not have the mentioned methods or 1004is not of another type appropriate for <code>Buffer.from()</code> variants.</p> 1005<h4>Static method: <code>Buffer.from(string[, encoding])</code><span><a class="mark" href="#buffer_static_method_buffer_from_string_encoding" id="buffer_static_method_buffer_from_string_encoding">#</a></span></h4> 1006<div class="api_metadata"> 1007<span>Added in: v5.10.0</span> 1008</div> 1009<ul> 1010<li><code>string</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> A string to encode.</li> 1011<li><code>encoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> The encoding of <code>string</code>. <strong>Default:</strong> <code>'utf8'</code>.</li> 1012</ul> 1013<p>Creates a new <code>Buffer</code> containing <code>string</code>. The <code>encoding</code> parameter identifies 1014the character encoding to be used when converting <code>string</code> into bytes.</p> 1015<pre><code class="language-js"><span class="hljs-keyword">const</span> buf1 = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(<span class="hljs-string">'this is a tést'</span>); 1016<span class="hljs-keyword">const</span> buf2 = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(<span class="hljs-string">'7468697320697320612074c3a97374'</span>, <span class="hljs-string">'hex'</span>); 1017 1018<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf1.<span class="hljs-title function_">toString</span>()); 1019<span class="hljs-comment">// Prints: this is a tést</span> 1020<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf2.<span class="hljs-title function_">toString</span>()); 1021<span class="hljs-comment">// Prints: this is a tést</span> 1022<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf1.<span class="hljs-title function_">toString</span>(<span class="hljs-string">'latin1'</span>)); 1023<span class="hljs-comment">// Prints: this is a tést</span></code></pre> 1024<p>A <code>TypeError</code> will be thrown if <code>string</code> is not a string or another type 1025appropriate for <code>Buffer.from()</code> variants.</p> 1026<h4>Static method: <code>Buffer.isBuffer(obj)</code><span><a class="mark" href="#buffer_static_method_buffer_isbuffer_obj" id="buffer_static_method_buffer_isbuffer_obj">#</a></span></h4> 1027<div class="api_metadata"> 1028<span>Added in: v0.1.101</span> 1029</div> 1030<ul> 1031<li><code>obj</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a></li> 1032<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type"><boolean></a></li> 1033</ul> 1034<p>Returns <code>true</code> if <code>obj</code> is a <code>Buffer</code>, <code>false</code> otherwise.</p> 1035<pre><code class="language-js"><span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">isBuffer</span>(<span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">alloc</span>(<span class="hljs-number">10</span>)); <span class="hljs-comment">// true</span> 1036<span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">isBuffer</span>(<span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(<span class="hljs-string">'foo'</span>)); <span class="hljs-comment">// true</span> 1037<span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">isBuffer</span>(<span class="hljs-string">'a string'</span>); <span class="hljs-comment">// false</span> 1038<span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">isBuffer</span>([]); <span class="hljs-comment">// false</span> 1039<span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">isBuffer</span>(<span class="hljs-keyword">new</span> <span class="hljs-title class_">Uint</span>8<span class="hljs-built_in">Array</span>(<span class="hljs-number">1024</span>)); <span class="hljs-comment">// false</span></code></pre> 1040<h4>Static method: <code>Buffer.isEncoding(encoding)</code><span><a class="mark" href="#buffer_static_method_buffer_isencoding_encoding" id="buffer_static_method_buffer_isencoding_encoding">#</a></span></h4> 1041<div class="api_metadata"> 1042<span>Added in: v0.9.1</span> 1043</div> 1044<ul> 1045<li><code>encoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> A character encoding name to check.</li> 1046<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type"><boolean></a></li> 1047</ul> 1048<p>Returns <code>true</code> if <code>encoding</code> is the name of a supported character encoding, 1049or <code>false</code> otherwise.</p> 1050<pre><code class="language-js"><span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">isEncoding</span>(<span class="hljs-string">'utf-8'</span>)); 1051<span class="hljs-comment">// Prints: true</span> 1052 1053<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">isEncoding</span>(<span class="hljs-string">'hex'</span>)); 1054<span class="hljs-comment">// Prints: true</span> 1055 1056<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">isEncoding</span>(<span class="hljs-string">'utf/8'</span>)); 1057<span class="hljs-comment">// Prints: false</span> 1058 1059<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">isEncoding</span>(<span class="hljs-string">''</span>)); 1060<span class="hljs-comment">// Prints: false</span></code></pre> 1061<h4>Class property: <code>Buffer.poolSize</code><span><a class="mark" href="#buffer_class_property_buffer_poolsize" id="buffer_class_property_buffer_poolsize">#</a></span></h4> 1062<div class="api_metadata"> 1063<span>Added in: v0.11.3</span> 1064</div> 1065<ul> 1066<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> <strong>Default:</strong> <code>8192</code></li> 1067</ul> 1068<p>This is the size (in bytes) of pre-allocated internal <code>Buffer</code> instances used 1069for pooling. This value may be modified.</p> 1070<h4><code>buf[index]</code><span><a class="mark" href="#buffer_buf_index" id="buffer_buf_index">#</a></span></h4> 1071<ul> 1072<li><code>index</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a></li> 1073</ul> 1074<p>The index operator <code>[index]</code> can be used to get and set the octet at position 1075<code>index</code> in <code>buf</code>. The values refer to individual bytes, so the legal value 1076range is between <code>0x00</code> and <code>0xFF</code> (hex) or <code>0</code> and <code>255</code> (decimal).</p> 1077<p>This operator is inherited from <code>Uint8Array</code>, so its behavior on out-of-bounds 1078access is the same as <code>Uint8Array</code>. In other words, <code>buf[index]</code> returns 1079<code>undefined</code> when <code>index</code> is negative or greater or equal to <code>buf.length</code>, and 1080<code>buf[index] = value</code> does not modify the buffer if <code>index</code> is negative or 1081<code>>= buf.length</code>.</p> 1082<pre><code class="language-js"><span class="hljs-comment">// Copy an ASCII string into a `Buffer` one byte at a time.</span> 1083<span class="hljs-comment">// (This only works for ASCII-only strings. In general, one should use</span> 1084<span class="hljs-comment">// `Buffer.from()` to perform this conversion.)</span> 1085 1086<span class="hljs-keyword">const</span> str = <span class="hljs-string">'Node.js'</span>; 1087<span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">allocUnsafe</span>(str.<span class="hljs-property">length</span>); 1088 1089<span class="hljs-keyword">for</span> (<span class="hljs-keyword">let</span> i = <span class="hljs-number">0</span>; i < str.<span class="hljs-property">length</span>; i++) { 1090 buf[i] = str.<span class="hljs-title function_">charCodeAt</span>(i); 1091} 1092 1093<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">toString</span>(<span class="hljs-string">'utf8'</span>)); 1094<span class="hljs-comment">// Prints: Node.js</span></code></pre> 1095<h4><code>buf.buffer</code><span><a class="mark" href="#buffer_buf_buffer" id="buffer_buf_buffer">#</a></span></h4> 1096<ul> 1097<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/ArrayBuffer" class="type"><ArrayBuffer></a> The underlying <code>ArrayBuffer</code> object based on which this <code>Buffer</code> 1098object is created.</li> 1099</ul> 1100<p>This <code>ArrayBuffer</code> is not guaranteed to correspond exactly to the original 1101<code>Buffer</code>. See the notes on <code>buf.byteOffset</code> for details.</p> 1102<pre><code class="language-js"><span class="hljs-keyword">const</span> arrayBuffer = <span class="hljs-keyword">new</span> <span class="hljs-title class_">ArrayBuffer</span>(<span class="hljs-number">16</span>); 1103<span class="hljs-keyword">const</span> buffer = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(arrayBuffer); 1104 1105<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buffer.<span class="hljs-property">buffer</span> === arrayBuffer); 1106<span class="hljs-comment">// Prints: true</span></code></pre> 1107<h4><code>buf.byteOffset</code><span><a class="mark" href="#buffer_buf_byteoffset" id="buffer_buf_byteoffset">#</a></span></h4> 1108<ul> 1109<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> The <code>byteOffset</code> of the <code>Buffer</code>s underlying <code>ArrayBuffer</code> object.</li> 1110</ul> 1111<p>When setting <code>byteOffset</code> in <code>Buffer.from(ArrayBuffer, byteOffset, length)</code>, 1112or sometimes when allocating a <code>Buffer</code> smaller than <code>Buffer.poolSize</code>, the 1113buffer does not start from a zero offset on the underlying <code>ArrayBuffer</code>.</p> 1114<p>This can cause problems when accessing the underlying <code>ArrayBuffer</code> directly 1115using <code>buf.buffer</code>, as other parts of the <code>ArrayBuffer</code> may be unrelated 1116to the <code>Buffer</code> object itself.</p> 1117<p>A common issue when creating a <code>TypedArray</code> object that shares its memory with 1118a <code>Buffer</code> is that in this case one needs to specify the <code>byteOffset</code> correctly:</p> 1119<pre><code class="language-js"><span class="hljs-comment">// Create a buffer smaller than `Buffer.poolSize`.</span> 1120<span class="hljs-keyword">const</span> nodeBuffer = <span class="hljs-keyword">new</span> <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>([<span class="hljs-number">0</span>, <span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-number">3</span>, <span class="hljs-number">4</span>, <span class="hljs-number">5</span>, <span class="hljs-number">6</span>, <span class="hljs-number">7</span>, <span class="hljs-number">8</span>, <span class="hljs-number">9</span>]); 1121 1122<span class="hljs-comment">// When casting the Node.js Buffer to an Int8Array, use the byteOffset</span> 1123<span class="hljs-comment">// to refer only to the part of `nodeBuffer.buffer` that contains the memory</span> 1124<span class="hljs-comment">// for `nodeBuffer`.</span> 1125<span class="hljs-keyword">new</span> <span class="hljs-title class_">Int</span>8<span class="hljs-built_in">Array</span>(nodeBuffer.<span class="hljs-property">buffer</span>, nodeBuffer.<span class="hljs-property">byteOffset</span>, nodeBuffer.<span class="hljs-property">length</span>);</code></pre> 1126<h4><code>buf.compare(target[, targetStart[, targetEnd[, sourceStart[, sourceEnd]]]])</code><span><a class="mark" href="#buffer_buf_compare_target_targetstart_targetend_sourcestart_sourceend" id="buffer_buf_compare_target_targetstart_targetend_sourcestart_sourceend">#</a></span></h4> 1127<div class="api_metadata"> 1128<details class="changelog"><summary>History</summary> 1129<table> 1130<tbody><tr><th>Version</th><th>Changes</th></tr> 1131<tr><td>v8.0.0</td> 1132<td><p>The <code>target</code> parameter can now be a <code>Uint8Array</code>.</p></td></tr> 1133<tr><td>v5.11.0</td> 1134<td><p>Additional parameters for specifying offsets are supported now.</p></td></tr> 1135<tr><td>v0.11.13</td> 1136<td><p><span>Added in: v0.11.13</span></p></td></tr> 1137</tbody></table> 1138</details> 1139</div> 1140<ul> 1141<li><code>target</code> <a href="buffer.html#buffer_class_buffer" class="type"><Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Uint8Array" class="type"><Uint8Array></a> A <code>Buffer</code> or <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Uint8Array"><code>Uint8Array</code></a> with which to 1142compare <code>buf</code>.</li> 1143<li><code>targetStart</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> The offset within <code>target</code> at which to begin 1144comparison. <strong>Default:</strong> <code>0</code>.</li> 1145<li><code>targetEnd</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> The offset within <code>target</code> at which to end comparison 1146(not inclusive). <strong>Default:</strong> <code>target.length</code>.</li> 1147<li><code>sourceStart</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> The offset within <code>buf</code> at which to begin comparison. 1148<strong>Default:</strong> <code>0</code>.</li> 1149<li><code>sourceEnd</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> The offset within <code>buf</code> at which to end comparison 1150(not inclusive). <strong>Default:</strong> <a href="#buffer_buf_length"><code>buf.length</code></a>.</li> 1151<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a></li> 1152</ul> 1153<p>Compares <code>buf</code> with <code>target</code> and returns a number indicating whether <code>buf</code> 1154comes before, after, or is the same as <code>target</code> in sort order. 1155Comparison is based on the actual sequence of bytes in each <code>Buffer</code>.</p> 1156<ul> 1157<li><code>0</code> is returned if <code>target</code> is the same as <code>buf</code></li> 1158<li><code>1</code> is returned if <code>target</code> should come <em>before</em> <code>buf</code> when sorted.</li> 1159<li><code>-1</code> is returned if <code>target</code> should come <em>after</em> <code>buf</code> when sorted.</li> 1160</ul> 1161<pre><code class="language-js"><span class="hljs-keyword">const</span> buf1 = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(<span class="hljs-string">'ABC'</span>); 1162<span class="hljs-keyword">const</span> buf2 = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(<span class="hljs-string">'BCD'</span>); 1163<span class="hljs-keyword">const</span> buf3 = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(<span class="hljs-string">'ABCD'</span>); 1164 1165<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf1.<span class="hljs-title function_">compare</span>(buf1)); 1166<span class="hljs-comment">// Prints: 0</span> 1167<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf1.<span class="hljs-title function_">compare</span>(buf2)); 1168<span class="hljs-comment">// Prints: -1</span> 1169<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf1.<span class="hljs-title function_">compare</span>(buf3)); 1170<span class="hljs-comment">// Prints: -1</span> 1171<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf2.<span class="hljs-title function_">compare</span>(buf1)); 1172<span class="hljs-comment">// Prints: 1</span> 1173<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf2.<span class="hljs-title function_">compare</span>(buf3)); 1174<span class="hljs-comment">// Prints: 1</span> 1175<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>([buf1, buf2, buf3].<span class="hljs-title function_">sort</span>(<span class="hljs-title class_">Buffer</span>.<span class="hljs-property">compare</span>)); 1176<span class="hljs-comment">// Prints: [ <Buffer 41 42 43>, <Buffer 41 42 43 44>, <Buffer 42 43 44> ]</span> 1177<span class="hljs-comment">// (This result is equal to: [buf1, buf3, buf2].)</span></code></pre> 1178<p>The optional <code>targetStart</code>, <code>targetEnd</code>, <code>sourceStart</code>, and <code>sourceEnd</code> 1179arguments can be used to limit the comparison to specific ranges within <code>target</code> 1180and <code>buf</code> respectively.</p> 1181<pre><code class="language-js"><span class="hljs-keyword">const</span> buf1 = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>([<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-number">3</span>, <span class="hljs-number">4</span>, <span class="hljs-number">5</span>, <span class="hljs-number">6</span>, <span class="hljs-number">7</span>, <span class="hljs-number">8</span>, <span class="hljs-number">9</span>]); 1182<span class="hljs-keyword">const</span> buf2 = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>([<span class="hljs-number">5</span>, <span class="hljs-number">6</span>, <span class="hljs-number">7</span>, <span class="hljs-number">8</span>, <span class="hljs-number">9</span>, <span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-number">3</span>, <span class="hljs-number">4</span>]); 1183 1184<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf1.<span class="hljs-title function_">compare</span>(buf2, <span class="hljs-number">5</span>, <span class="hljs-number">9</span>, <span class="hljs-number">0</span>, <span class="hljs-number">4</span>)); 1185<span class="hljs-comment">// Prints: 0</span> 1186<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf1.<span class="hljs-title function_">compare</span>(buf2, <span class="hljs-number">0</span>, <span class="hljs-number">6</span>, <span class="hljs-number">4</span>)); 1187<span class="hljs-comment">// Prints: -1</span> 1188<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf1.<span class="hljs-title function_">compare</span>(buf2, <span class="hljs-number">5</span>, <span class="hljs-number">6</span>, <span class="hljs-number">5</span>)); 1189<span class="hljs-comment">// Prints: 1</span></code></pre> 1190<p><a href="errors.html#ERR_OUT_OF_RANGE"><code>ERR_OUT_OF_RANGE</code></a> is thrown if <code>targetStart < 0</code>, <code>sourceStart < 0</code>, 1191<code>targetEnd > target.byteLength</code>, or <code>sourceEnd > source.byteLength</code>.</p> 1192<h4><code>buf.copy(target[, targetStart[, sourceStart[, sourceEnd]]])</code><span><a class="mark" href="#buffer_buf_copy_target_targetstart_sourcestart_sourceend" id="buffer_buf_copy_target_targetstart_sourcestart_sourceend">#</a></span></h4> 1193<div class="api_metadata"> 1194<span>Added in: v0.1.90</span> 1195</div> 1196<ul> 1197<li><code>target</code> <a href="buffer.html#buffer_class_buffer" class="type"><Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Uint8Array" class="type"><Uint8Array></a> A <code>Buffer</code> or <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Uint8Array"><code>Uint8Array</code></a> to copy into.</li> 1198<li><code>targetStart</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> The offset within <code>target</code> at which to begin 1199writing. <strong>Default:</strong> <code>0</code>.</li> 1200<li><code>sourceStart</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> The offset within <code>buf</code> from which to begin copying. 1201<strong>Default:</strong> <code>0</code>.</li> 1202<li><code>sourceEnd</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> The offset within <code>buf</code> at which to stop copying (not 1203inclusive). <strong>Default:</strong> <a href="#buffer_buf_length"><code>buf.length</code></a>.</li> 1204<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> The number of bytes copied.</li> 1205</ul> 1206<p>Copies data from a region of <code>buf</code> to a region in <code>target</code>, even if the <code>target</code> 1207memory region overlaps with <code>buf</code>.</p> 1208<p><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray/set"><code>TypedArray.prototype.set()</code></a> performs the same operation, and is available 1209for all TypedArrays, including Node.js <code>Buffer</code>s, although it takes 1210different function arguments.</p> 1211<pre><code class="language-js"><span class="hljs-comment">// Create two `Buffer` instances.</span> 1212<span class="hljs-keyword">const</span> buf1 = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">allocUnsafe</span>(<span class="hljs-number">26</span>); 1213<span class="hljs-keyword">const</span> buf2 = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">allocUnsafe</span>(<span class="hljs-number">26</span>).<span class="hljs-title function_">fill</span>(<span class="hljs-string">'!'</span>); 1214 1215<span class="hljs-keyword">for</span> (<span class="hljs-keyword">let</span> i = <span class="hljs-number">0</span>; i < <span class="hljs-number">26</span>; i++) { 1216 <span class="hljs-comment">// 97 is the decimal ASCII value for 'a'.</span> 1217 buf1[i] = i + <span class="hljs-number">97</span>; 1218} 1219 1220<span class="hljs-comment">// Copy `buf1` bytes 16 through 19 into `buf2` starting at byte 8 of `buf2`.</span> 1221buf1.<span class="hljs-title function_">copy</span>(buf2, <span class="hljs-number">8</span>, <span class="hljs-number">16</span>, <span class="hljs-number">20</span>); 1222<span class="hljs-comment">// This is equivalent to:</span> 1223<span class="hljs-comment">// buf2.set(buf1.subarray(16, 20), 8);</span> 1224 1225<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf2.<span class="hljs-title function_">toString</span>(<span class="hljs-string">'ascii'</span>, <span class="hljs-number">0</span>, <span class="hljs-number">25</span>)); 1226<span class="hljs-comment">// Prints: !!!!!!!!qrst!!!!!!!!!!!!!</span></code></pre> 1227<pre><code class="language-js"><span class="hljs-comment">// Create a `Buffer` and copy data from one region to an overlapping region</span> 1228<span class="hljs-comment">// within the same `Buffer`.</span> 1229 1230<span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">allocUnsafe</span>(<span class="hljs-number">26</span>); 1231 1232<span class="hljs-keyword">for</span> (<span class="hljs-keyword">let</span> i = <span class="hljs-number">0</span>; i < <span class="hljs-number">26</span>; i++) { 1233 <span class="hljs-comment">// 97 is the decimal ASCII value for 'a'.</span> 1234 buf[i] = i + <span class="hljs-number">97</span>; 1235} 1236 1237buf.<span class="hljs-title function_">copy</span>(buf, <span class="hljs-number">0</span>, <span class="hljs-number">4</span>, <span class="hljs-number">10</span>); 1238 1239<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">toString</span>()); 1240<span class="hljs-comment">// Prints: efghijghijklmnopqrstuvwxyz</span></code></pre> 1241<h4><code>buf.entries()</code><span><a class="mark" href="#buffer_buf_entries" id="buffer_buf_entries">#</a></span></h4> 1242<div class="api_metadata"> 1243<span>Added in: v1.1.0</span> 1244</div> 1245<ul> 1246<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols#The_iterator_protocol" class="type"><Iterator></a></li> 1247</ul> 1248<p>Creates and returns an <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols">iterator</a> of <code>[index, byte]</code> pairs from the contents 1249of <code>buf</code>.</p> 1250<pre><code class="language-js"><span class="hljs-comment">// Log the entire contents of a `Buffer`.</span> 1251 1252<span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(<span class="hljs-string">'buffer'</span>); 1253 1254<span class="hljs-keyword">for</span> (<span class="hljs-keyword">const</span> pair <span class="hljs-keyword">of</span> buf.<span class="hljs-title function_">entries</span>()) { 1255 <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(pair); 1256} 1257<span class="hljs-comment">// Prints:</span> 1258<span class="hljs-comment">// [0, 98]</span> 1259<span class="hljs-comment">// [1, 117]</span> 1260<span class="hljs-comment">// [2, 102]</span> 1261<span class="hljs-comment">// [3, 102]</span> 1262<span class="hljs-comment">// [4, 101]</span> 1263<span class="hljs-comment">// [5, 114]</span></code></pre> 1264<h4><code>buf.equals(otherBuffer)</code><span><a class="mark" href="#buffer_buf_equals_otherbuffer" id="buffer_buf_equals_otherbuffer">#</a></span></h4> 1265<div class="api_metadata"> 1266<details class="changelog"><summary>History</summary> 1267<table> 1268<tbody><tr><th>Version</th><th>Changes</th></tr> 1269<tr><td>v8.0.0</td> 1270<td><p>The arguments can now be <code>Uint8Array</code>s.</p></td></tr> 1271<tr><td>v0.11.13</td> 1272<td><p><span>Added in: v0.11.13</span></p></td></tr> 1273</tbody></table> 1274</details> 1275</div> 1276<ul> 1277<li><code>otherBuffer</code> <a href="buffer.html#buffer_class_buffer" class="type"><Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Uint8Array" class="type"><Uint8Array></a> A <code>Buffer</code> or <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Uint8Array"><code>Uint8Array</code></a> with which to 1278compare <code>buf</code>.</li> 1279<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type"><boolean></a></li> 1280</ul> 1281<p>Returns <code>true</code> if both <code>buf</code> and <code>otherBuffer</code> have exactly the same bytes, 1282<code>false</code> otherwise. Equivalent to 1283<a href="#buffer_buf_compare_target_targetstart_targetend_sourcestart_sourceend"><code>buf.compare(otherBuffer) === 0</code></a>.</p> 1284<pre><code class="language-js"><span class="hljs-keyword">const</span> buf1 = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(<span class="hljs-string">'ABC'</span>); 1285<span class="hljs-keyword">const</span> buf2 = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(<span class="hljs-string">'414243'</span>, <span class="hljs-string">'hex'</span>); 1286<span class="hljs-keyword">const</span> buf3 = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(<span class="hljs-string">'ABCD'</span>); 1287 1288<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf1.<span class="hljs-title function_">equals</span>(buf2)); 1289<span class="hljs-comment">// Prints: true</span> 1290<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf1.<span class="hljs-title function_">equals</span>(buf3)); 1291<span class="hljs-comment">// Prints: false</span></code></pre> 1292<h4><code>buf.fill(value[, offset[, end]][, encoding])</code><span><a class="mark" href="#buffer_buf_fill_value_offset_end_encoding" id="buffer_buf_fill_value_offset_end_encoding">#</a></span></h4> 1293<div class="api_metadata"> 1294<details class="changelog"><summary>History</summary> 1295<table> 1296<tbody><tr><th>Version</th><th>Changes</th></tr> 1297<tr><td>v11.0.0</td> 1298<td><p>Throws <code>ERR_OUT_OF_RANGE</code> instead of <code>ERR_INDEX_OUT_OF_RANGE</code>.</p></td></tr> 1299<tr><td>v10.0.0</td> 1300<td><p>Negative <code>end</code> values throw an <code>ERR_INDEX_OUT_OF_RANGE</code> error.</p></td></tr> 1301<tr><td>v10.0.0</td> 1302<td><p>Attempting to fill a non-zero length buffer with a zero length buffer triggers a thrown exception.</p></td></tr> 1303<tr><td>v10.0.0</td> 1304<td><p>Specifying an invalid string for <code>value</code> triggers a thrown exception.</p></td></tr> 1305<tr><td>v5.7.0</td> 1306<td><p>The <code>encoding</code> parameter is supported now.</p></td></tr> 1307<tr><td>v0.5.0</td> 1308<td><p><span>Added in: v0.5.0</span></p></td></tr> 1309</tbody></table> 1310</details> 1311</div> 1312<ul> 1313<li><code>value</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> | <a href="buffer.html#buffer_class_buffer" class="type"><Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Uint8Array" class="type"><Uint8Array></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> The value with which to fill <code>buf</code>.</li> 1314<li><code>offset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to skip before starting to fill <code>buf</code>. 1315<strong>Default:</strong> <code>0</code>.</li> 1316<li><code>end</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Where to stop filling <code>buf</code> (not inclusive). <strong>Default:</strong> 1317<a href="#buffer_buf_length"><code>buf.length</code></a>.</li> 1318<li><code>encoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> The encoding for <code>value</code> if <code>value</code> is a string. 1319<strong>Default:</strong> <code>'utf8'</code>.</li> 1320<li>Returns: <a href="buffer.html#buffer_class_buffer" class="type"><Buffer></a> A reference to <code>buf</code>.</li> 1321</ul> 1322<p>Fills <code>buf</code> with the specified <code>value</code>. If the <code>offset</code> and <code>end</code> are not given, 1323the entire <code>buf</code> will be filled:</p> 1324<pre><code class="language-js"><span class="hljs-comment">// Fill a `Buffer` with the ASCII character 'h'.</span> 1325 1326<span class="hljs-keyword">const</span> b = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">allocUnsafe</span>(<span class="hljs-number">50</span>).<span class="hljs-title function_">fill</span>(<span class="hljs-string">'h'</span>); 1327 1328<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(b.<span class="hljs-title function_">toString</span>()); 1329<span class="hljs-comment">// Prints: hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh</span></code></pre> 1330<p><code>value</code> is coerced to a <code>uint32</code> value if it is not a string, <code>Buffer</code>, or 1331integer. If the resulting integer is greater than <code>255</code> (decimal), <code>buf</code> will be 1332filled with <code>value & 255</code>.</p> 1333<p>If the final write of a <code>fill()</code> operation falls on a multi-byte character, 1334then only the bytes of that character that fit into <code>buf</code> are written:</p> 1335<pre><code class="language-js"><span class="hljs-comment">// Fill a `Buffer` with character that takes up two bytes in UTF-8.</span> 1336 1337<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">allocUnsafe</span>(<span class="hljs-number">5</span>).<span class="hljs-title function_">fill</span>(<span class="hljs-string">'\u0222'</span>)); 1338<span class="hljs-comment">// Prints: <Buffer c8 a2 c8 a2 c8></span></code></pre> 1339<p>If <code>value</code> contains invalid characters, it is truncated; if no valid 1340fill data remains, an exception is thrown:</p> 1341<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">allocUnsafe</span>(<span class="hljs-number">5</span>); 1342 1343<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">fill</span>(<span class="hljs-string">'a'</span>)); 1344<span class="hljs-comment">// Prints: <Buffer 61 61 61 61 61></span> 1345<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">fill</span>(<span class="hljs-string">'aazz'</span>, <span class="hljs-string">'hex'</span>)); 1346<span class="hljs-comment">// Prints: <Buffer aa aa aa aa aa></span> 1347<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">fill</span>(<span class="hljs-string">'zz'</span>, <span class="hljs-string">'hex'</span>)); 1348<span class="hljs-comment">// Throws an exception.</span></code></pre> 1349<h4><code>buf.includes(value[, byteOffset][, encoding])</code><span><a class="mark" href="#buffer_buf_includes_value_byteoffset_encoding" id="buffer_buf_includes_value_byteoffset_encoding">#</a></span></h4> 1350<div class="api_metadata"> 1351<span>Added in: v5.3.0</span> 1352</div> 1353<ul> 1354<li><code>value</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> | <a href="buffer.html#buffer_class_buffer" class="type"><Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Uint8Array" class="type"><Uint8Array></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> What to search for.</li> 1355<li><code>byteOffset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Where to begin searching in <code>buf</code>. If negative, then 1356offset is calculated from the end of <code>buf</code>. <strong>Default:</strong> <code>0</code>.</li> 1357<li><code>encoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> If <code>value</code> is a string, this is its encoding. 1358<strong>Default:</strong> <code>'utf8'</code>.</li> 1359<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type"><boolean></a> <code>true</code> if <code>value</code> was found in <code>buf</code>, <code>false</code> otherwise.</li> 1360</ul> 1361<p>Equivalent to <a href="#buffer_buf_indexof_value_byteoffset_encoding"><code>buf.indexOf() !== -1</code></a>.</p> 1362<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(<span class="hljs-string">'this is a buffer'</span>); 1363 1364<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">includes</span>(<span class="hljs-string">'this'</span>)); 1365<span class="hljs-comment">// Prints: true</span> 1366<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">includes</span>(<span class="hljs-string">'is'</span>)); 1367<span class="hljs-comment">// Prints: true</span> 1368<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">includes</span>(<span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(<span class="hljs-string">'a buffer'</span>))); 1369<span class="hljs-comment">// Prints: true</span> 1370<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">includes</span>(<span class="hljs-number">97</span>)); 1371<span class="hljs-comment">// Prints: true (97 is the decimal ASCII value for 'a')</span> 1372<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">includes</span>(<span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(<span class="hljs-string">'a buffer example'</span>))); 1373<span class="hljs-comment">// Prints: false</span> 1374<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">includes</span>(<span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(<span class="hljs-string">'a buffer example'</span>).<span class="hljs-title function_">slice</span>(<span class="hljs-number">0</span>, <span class="hljs-number">8</span>))); 1375<span class="hljs-comment">// Prints: true</span> 1376<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">includes</span>(<span class="hljs-string">'this'</span>, <span class="hljs-number">4</span>)); 1377<span class="hljs-comment">// Prints: false</span></code></pre> 1378<h4><code>buf.indexOf(value[, byteOffset][, encoding])</code><span><a class="mark" href="#buffer_buf_indexof_value_byteoffset_encoding" id="buffer_buf_indexof_value_byteoffset_encoding">#</a></span></h4> 1379<div class="api_metadata"> 1380<details class="changelog"><summary>History</summary> 1381<table> 1382<tbody><tr><th>Version</th><th>Changes</th></tr> 1383<tr><td>v8.0.0</td> 1384<td><p>The <code>value</code> can now be a <code>Uint8Array</code>.</p></td></tr> 1385<tr><td>v5.7.0, v4.4.0</td> 1386<td><p>When <code>encoding</code> is being passed, the <code>byteOffset</code> parameter is no longer required.</p></td></tr> 1387<tr><td>v1.5.0</td> 1388<td><p><span>Added in: v1.5.0</span></p></td></tr> 1389</tbody></table> 1390</details> 1391</div> 1392<ul> 1393<li><code>value</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> | <a href="buffer.html#buffer_class_buffer" class="type"><Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Uint8Array" class="type"><Uint8Array></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> What to search for.</li> 1394<li><code>byteOffset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Where to begin searching in <code>buf</code>. If negative, then 1395offset is calculated from the end of <code>buf</code>. <strong>Default:</strong> <code>0</code>.</li> 1396<li><code>encoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> If <code>value</code> is a string, this is the encoding used to 1397determine the binary representation of the string that will be searched for in 1398<code>buf</code>. <strong>Default:</strong> <code>'utf8'</code>.</li> 1399<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> The index of the first occurrence of <code>value</code> in <code>buf</code>, or 1400<code>-1</code> if <code>buf</code> does not contain <code>value</code>.</li> 1401</ul> 1402<p>If <code>value</code> is:</p> 1403<ul> 1404<li>a string, <code>value</code> is interpreted according to the character encoding in 1405<code>encoding</code>.</li> 1406<li>a <code>Buffer</code> or <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Uint8Array"><code>Uint8Array</code></a>, <code>value</code> will be used in its entirety. 1407To compare a partial <code>Buffer</code>, use <a href="#buffer_buf_slice_start_end"><code>buf.slice()</code></a>.</li> 1408<li>a number, <code>value</code> will be interpreted as an unsigned 8-bit integer 1409value between <code>0</code> and <code>255</code>.</li> 1410</ul> 1411<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(<span class="hljs-string">'this is a buffer'</span>); 1412 1413<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">indexOf</span>(<span class="hljs-string">'this'</span>)); 1414<span class="hljs-comment">// Prints: 0</span> 1415<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">indexOf</span>(<span class="hljs-string">'is'</span>)); 1416<span class="hljs-comment">// Prints: 2</span> 1417<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">indexOf</span>(<span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(<span class="hljs-string">'a buffer'</span>))); 1418<span class="hljs-comment">// Prints: 8</span> 1419<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">indexOf</span>(<span class="hljs-number">97</span>)); 1420<span class="hljs-comment">// Prints: 8 (97 is the decimal ASCII value for 'a')</span> 1421<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">indexOf</span>(<span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(<span class="hljs-string">'a buffer example'</span>))); 1422<span class="hljs-comment">// Prints: -1</span> 1423<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">indexOf</span>(<span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(<span class="hljs-string">'a buffer example'</span>).<span class="hljs-title function_">slice</span>(<span class="hljs-number">0</span>, <span class="hljs-number">8</span>))); 1424<span class="hljs-comment">// Prints: 8</span> 1425 1426<span class="hljs-keyword">const</span> utf16Buffer = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(<span class="hljs-string">'\u039a\u0391\u03a3\u03a3\u0395'</span>, <span class="hljs-string">'utf16le'</span>); 1427 1428<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(utf16Buffer.<span class="hljs-title function_">indexOf</span>(<span class="hljs-string">'\u03a3'</span>, <span class="hljs-number">0</span>, <span class="hljs-string">'utf16le'</span>)); 1429<span class="hljs-comment">// Prints: 4</span> 1430<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(utf16Buffer.<span class="hljs-title function_">indexOf</span>(<span class="hljs-string">'\u03a3'</span>, -<span class="hljs-number">4</span>, <span class="hljs-string">'utf16le'</span>)); 1431<span class="hljs-comment">// Prints: 6</span></code></pre> 1432<p>If <code>value</code> is not a string, number, or <code>Buffer</code>, this method will throw a 1433<code>TypeError</code>. If <code>value</code> is a number, it will be coerced to a valid byte value, 1434an integer between 0 and 255.</p> 1435<p>If <code>byteOffset</code> is not a number, it will be coerced to a number. If the result 1436of coercion is <code>NaN</code> or <code>0</code>, then the entire buffer will be searched. This 1437behavior matches <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/indexOf"><code>String.prototype.indexOf()</code></a>.</p> 1438<pre><code class="language-js"><span class="hljs-keyword">const</span> b = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(<span class="hljs-string">'abcdef'</span>); 1439 1440<span class="hljs-comment">// Passing a value that's a number, but not a valid byte.</span> 1441<span class="hljs-comment">// Prints: 2, equivalent to searching for 99 or 'c'.</span> 1442<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(b.<span class="hljs-title function_">indexOf</span>(<span class="hljs-number">99.9</span>)); 1443<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(b.<span class="hljs-title function_">indexOf</span>(<span class="hljs-number">256</span> + <span class="hljs-number">99</span>)); 1444 1445<span class="hljs-comment">// Passing a byteOffset that coerces to NaN or 0.</span> 1446<span class="hljs-comment">// Prints: 1, searching the whole buffer.</span> 1447<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(b.<span class="hljs-title function_">indexOf</span>(<span class="hljs-string">'b'</span>, <span class="hljs-literal">undefined</span>)); 1448<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(b.<span class="hljs-title function_">indexOf</span>(<span class="hljs-string">'b'</span>, {})); 1449<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(b.<span class="hljs-title function_">indexOf</span>(<span class="hljs-string">'b'</span>, <span class="hljs-literal">null</span>)); 1450<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(b.<span class="hljs-title function_">indexOf</span>(<span class="hljs-string">'b'</span>, []));</code></pre> 1451<p>If <code>value</code> is an empty string or empty <code>Buffer</code> and <code>byteOffset</code> is less 1452than <code>buf.length</code>, <code>byteOffset</code> will be returned. If <code>value</code> is empty and 1453<code>byteOffset</code> is at least <code>buf.length</code>, <code>buf.length</code> will be returned.</p> 1454<h4><code>buf.keys()</code><span><a class="mark" href="#buffer_buf_keys" id="buffer_buf_keys">#</a></span></h4> 1455<div class="api_metadata"> 1456<span>Added in: v1.1.0</span> 1457</div> 1458<ul> 1459<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols#The_iterator_protocol" class="type"><Iterator></a></li> 1460</ul> 1461<p>Creates and returns an <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols">iterator</a> of <code>buf</code> keys (indices).</p> 1462<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(<span class="hljs-string">'buffer'</span>); 1463 1464<span class="hljs-keyword">for</span> (<span class="hljs-keyword">const</span> key <span class="hljs-keyword">of</span> buf.<span class="hljs-title function_">keys</span>()) { 1465 <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(key); 1466} 1467<span class="hljs-comment">// Prints:</span> 1468<span class="hljs-comment">// 0</span> 1469<span class="hljs-comment">// 1</span> 1470<span class="hljs-comment">// 2</span> 1471<span class="hljs-comment">// 3</span> 1472<span class="hljs-comment">// 4</span> 1473<span class="hljs-comment">// 5</span></code></pre> 1474<h4><code>buf.lastIndexOf(value[, byteOffset][, encoding])</code><span><a class="mark" href="#buffer_buf_lastindexof_value_byteoffset_encoding" id="buffer_buf_lastindexof_value_byteoffset_encoding">#</a></span></h4> 1475<div class="api_metadata"> 1476<details class="changelog"><summary>History</summary> 1477<table> 1478<tbody><tr><th>Version</th><th>Changes</th></tr> 1479<tr><td>v8.0.0</td> 1480<td><p>The <code>value</code> can now be a <code>Uint8Array</code>.</p></td></tr> 1481<tr><td>v6.0.0</td> 1482<td><p><span>Added in: v6.0.0</span></p></td></tr> 1483</tbody></table> 1484</details> 1485</div> 1486<ul> 1487<li><code>value</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> | <a href="buffer.html#buffer_class_buffer" class="type"><Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Uint8Array" class="type"><Uint8Array></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> What to search for.</li> 1488<li><code>byteOffset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Where to begin searching in <code>buf</code>. If negative, then 1489offset is calculated from the end of <code>buf</code>. <strong>Default:</strong> 1490<code>buf.length - 1</code>.</li> 1491<li><code>encoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> If <code>value</code> is a string, this is the encoding used to 1492determine the binary representation of the string that will be searched for in 1493<code>buf</code>. <strong>Default:</strong> <code>'utf8'</code>.</li> 1494<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> The index of the last occurrence of <code>value</code> in <code>buf</code>, or 1495<code>-1</code> if <code>buf</code> does not contain <code>value</code>.</li> 1496</ul> 1497<p>Identical to <a href="#buffer_buf_indexof_value_byteoffset_encoding"><code>buf.indexOf()</code></a>, except the last occurrence of <code>value</code> is found 1498rather than the first occurrence.</p> 1499<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(<span class="hljs-string">'this buffer is a buffer'</span>); 1500 1501<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">lastIndexOf</span>(<span class="hljs-string">'this'</span>)); 1502<span class="hljs-comment">// Prints: 0</span> 1503<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">lastIndexOf</span>(<span class="hljs-string">'buffer'</span>)); 1504<span class="hljs-comment">// Prints: 17</span> 1505<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">lastIndexOf</span>(<span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(<span class="hljs-string">'buffer'</span>))); 1506<span class="hljs-comment">// Prints: 17</span> 1507<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">lastIndexOf</span>(<span class="hljs-number">97</span>)); 1508<span class="hljs-comment">// Prints: 15 (97 is the decimal ASCII value for 'a')</span> 1509<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">lastIndexOf</span>(<span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(<span class="hljs-string">'yolo'</span>))); 1510<span class="hljs-comment">// Prints: -1</span> 1511<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">lastIndexOf</span>(<span class="hljs-string">'buffer'</span>, <span class="hljs-number">5</span>)); 1512<span class="hljs-comment">// Prints: 5</span> 1513<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">lastIndexOf</span>(<span class="hljs-string">'buffer'</span>, <span class="hljs-number">4</span>)); 1514<span class="hljs-comment">// Prints: -1</span> 1515 1516<span class="hljs-keyword">const</span> utf16Buffer = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(<span class="hljs-string">'\u039a\u0391\u03a3\u03a3\u0395'</span>, <span class="hljs-string">'utf16le'</span>); 1517 1518<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(utf16Buffer.<span class="hljs-title function_">lastIndexOf</span>(<span class="hljs-string">'\u03a3'</span>, <span class="hljs-literal">undefined</span>, <span class="hljs-string">'utf16le'</span>)); 1519<span class="hljs-comment">// Prints: 6</span> 1520<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(utf16Buffer.<span class="hljs-title function_">lastIndexOf</span>(<span class="hljs-string">'\u03a3'</span>, -<span class="hljs-number">5</span>, <span class="hljs-string">'utf16le'</span>)); 1521<span class="hljs-comment">// Prints: 4</span></code></pre> 1522<p>If <code>value</code> is not a string, number, or <code>Buffer</code>, this method will throw a 1523<code>TypeError</code>. If <code>value</code> is a number, it will be coerced to a valid byte value, 1524an integer between 0 and 255.</p> 1525<p>If <code>byteOffset</code> is not a number, it will be coerced to a number. Any arguments 1526that coerce to <code>NaN</code>, like <code>{}</code> or <code>undefined</code>, will search the whole buffer. 1527This behavior matches <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/lastIndexOf"><code>String.prototype.lastIndexOf()</code></a>.</p> 1528<pre><code class="language-js"><span class="hljs-keyword">const</span> b = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(<span class="hljs-string">'abcdef'</span>); 1529 1530<span class="hljs-comment">// Passing a value that's a number, but not a valid byte.</span> 1531<span class="hljs-comment">// Prints: 2, equivalent to searching for 99 or 'c'.</span> 1532<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(b.<span class="hljs-title function_">lastIndexOf</span>(<span class="hljs-number">99.9</span>)); 1533<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(b.<span class="hljs-title function_">lastIndexOf</span>(<span class="hljs-number">256</span> + <span class="hljs-number">99</span>)); 1534 1535<span class="hljs-comment">// Passing a byteOffset that coerces to NaN.</span> 1536<span class="hljs-comment">// Prints: 1, searching the whole buffer.</span> 1537<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(b.<span class="hljs-title function_">lastIndexOf</span>(<span class="hljs-string">'b'</span>, <span class="hljs-literal">undefined</span>)); 1538<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(b.<span class="hljs-title function_">lastIndexOf</span>(<span class="hljs-string">'b'</span>, {})); 1539 1540<span class="hljs-comment">// Passing a byteOffset that coerces to 0.</span> 1541<span class="hljs-comment">// Prints: -1, equivalent to passing 0.</span> 1542<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(b.<span class="hljs-title function_">lastIndexOf</span>(<span class="hljs-string">'b'</span>, <span class="hljs-literal">null</span>)); 1543<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(b.<span class="hljs-title function_">lastIndexOf</span>(<span class="hljs-string">'b'</span>, []));</code></pre> 1544<p>If <code>value</code> is an empty string or empty <code>Buffer</code>, <code>byteOffset</code> will be returned.</p> 1545<h4><code>buf.length</code><span><a class="mark" href="#buffer_buf_length" id="buffer_buf_length">#</a></span></h4> 1546<div class="api_metadata"> 1547<span>Added in: v0.1.90</span> 1548</div> 1549<ul> 1550<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a></li> 1551</ul> 1552<p>Returns the number of bytes in <code>buf</code>.</p> 1553<pre><code class="language-js"><span class="hljs-comment">// Create a `Buffer` and write a shorter string to it using UTF-8.</span> 1554 1555<span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">alloc</span>(<span class="hljs-number">1234</span>); 1556 1557<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-property">length</span>); 1558<span class="hljs-comment">// Prints: 1234</span> 1559 1560buf.<span class="hljs-title function_">write</span>(<span class="hljs-string">'some string'</span>, <span class="hljs-number">0</span>, <span class="hljs-string">'utf8'</span>); 1561 1562<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-property">length</span>); 1563<span class="hljs-comment">// Prints: 1234</span></code></pre> 1564<h4><code>buf.parent</code><span><a class="mark" href="#buffer_buf_parent" id="buffer_buf_parent">#</a></span></h4> 1565<div class="api_metadata"> 1566<span>Deprecated since: v8.0.0</span> 1567</div> 1568<p></p><div class="api_stability api_stability_0"><a href="documentation.html#documentation_stability_index">Stability: 0</a> - Deprecated: Use <a href="#buffer_buf_buffer"><code>buf.buffer</code></a> instead.</div><p></p> 1569<p>The <code>buf.parent</code> property is a deprecated alias for <code>buf.buffer</code>.</p> 1570<h4><code>buf.readBigInt64BE([offset])</code><span><a class="mark" href="#buffer_buf_readbigint64be_offset" id="buffer_buf_readbigint64be_offset">#</a></span></h4> 1571<div class="api_metadata"> 1572<span>Added in: v12.0.0, v10.20.0</span> 1573</div> 1574<ul> 1575<li><code>offset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to skip before starting to read. Must 1576satisfy: <code>0 <= offset <= buf.length - 8</code>. <strong>Default:</strong> <code>0</code>.</li> 1577<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/BigInt" class="type"><bigint></a></li> 1578</ul> 1579<p>Reads a signed, big-endian 64-bit integer from <code>buf</code> at the specified <code>offset</code>.</p> 1580<p>Integers read from a <code>Buffer</code> are interpreted as two's complement signed 1581values.</p> 1582<h4><code>buf.readBigInt64LE([offset])</code><span><a class="mark" href="#buffer_buf_readbigint64le_offset" id="buffer_buf_readbigint64le_offset">#</a></span></h4> 1583<div class="api_metadata"> 1584<span>Added in: v12.0.0, v10.20.0</span> 1585</div> 1586<ul> 1587<li><code>offset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to skip before starting to read. Must 1588satisfy: <code>0 <= offset <= buf.length - 8</code>. <strong>Default:</strong> <code>0</code>.</li> 1589<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/BigInt" class="type"><bigint></a></li> 1590</ul> 1591<p>Reads a signed, little-endian 64-bit integer from <code>buf</code> at the specified 1592<code>offset</code>.</p> 1593<p>Integers read from a <code>Buffer</code> are interpreted as two's complement signed 1594values.</p> 1595<h4><code>buf.readBigUInt64BE([offset])</code><span><a class="mark" href="#buffer_buf_readbiguint64be_offset" id="buffer_buf_readbiguint64be_offset">#</a></span></h4> 1596<div class="api_metadata"> 1597<details class="changelog"><summary>History</summary> 1598<table> 1599<tbody><tr><th>Version</th><th>Changes</th></tr> 1600<tr><td>v14.10.0</td> 1601<td><p>This function is also available as <code>buf.readBigUint64BE()</code>.</p></td></tr> 1602<tr><td>v12.0.0, v10.20.0</td> 1603<td><p><span>Added in: v12.0.0, v10.20.0</span></p></td></tr> 1604</tbody></table> 1605</details> 1606</div> 1607<ul> 1608<li><code>offset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to skip before starting to read. Must 1609satisfy: <code>0 <= offset <= buf.length - 8</code>. <strong>Default:</strong> <code>0</code>.</li> 1610<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/BigInt" class="type"><bigint></a></li> 1611</ul> 1612<p>Reads an unsigned, big-endian 64-bit integer from <code>buf</code> at the specified 1613<code>offset</code>.</p> 1614<p>This function is also available under the <code>readBigUint64BE</code> alias.</p> 1615<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>([<span class="hljs-number">0x00</span>, <span class="hljs-number">0x00</span>, <span class="hljs-number">0x00</span>, <span class="hljs-number">0x00</span>, <span class="hljs-number">0xff</span>, <span class="hljs-number">0xff</span>, <span class="hljs-number">0xff</span>, <span class="hljs-number">0xff</span>]); 1616 1617<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">readBigUInt64BE</span>(<span class="hljs-number">0</span>)); 1618<span class="hljs-comment">// Prints: 4294967295n</span></code></pre> 1619<h4><code>buf.readBigUInt64LE([offset])</code><span><a class="mark" href="#buffer_buf_readbiguint64le_offset" id="buffer_buf_readbiguint64le_offset">#</a></span></h4> 1620<div class="api_metadata"> 1621<details class="changelog"><summary>History</summary> 1622<table> 1623<tbody><tr><th>Version</th><th>Changes</th></tr> 1624<tr><td>v14.10.0, v12.19.0</td> 1625<td><p>This function is also available as <code>buf.readBigUint64LE()</code>.</p></td></tr> 1626<tr><td>v12.0.0, v10.20.0</td> 1627<td><p><span>Added in: v12.0.0, v10.20.0</span></p></td></tr> 1628</tbody></table> 1629</details> 1630</div> 1631<ul> 1632<li><code>offset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to skip before starting to read. Must 1633satisfy: <code>0 <= offset <= buf.length - 8</code>. <strong>Default:</strong> <code>0</code>.</li> 1634<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/BigInt" class="type"><bigint></a></li> 1635</ul> 1636<p>Reads an unsigned, little-endian 64-bit integer from <code>buf</code> at the specified 1637<code>offset</code>.</p> 1638<p>This function is also available under the <code>readBigUint64LE</code> alias.</p> 1639<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>([<span class="hljs-number">0x00</span>, <span class="hljs-number">0x00</span>, <span class="hljs-number">0x00</span>, <span class="hljs-number">0x00</span>, <span class="hljs-number">0xff</span>, <span class="hljs-number">0xff</span>, <span class="hljs-number">0xff</span>, <span class="hljs-number">0xff</span>]); 1640 1641<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">readBigUInt64LE</span>(<span class="hljs-number">0</span>)); 1642<span class="hljs-comment">// Prints: 18446744069414584320n</span></code></pre> 1643<h4><code>buf.readDoubleBE([offset])</code><span><a class="mark" href="#buffer_buf_readdoublebe_offset" id="buffer_buf_readdoublebe_offset">#</a></span></h4> 1644<div class="api_metadata"> 1645<details class="changelog"><summary>History</summary> 1646<table> 1647<tbody><tr><th>Version</th><th>Changes</th></tr> 1648<tr><td>v10.0.0</td> 1649<td><p>Removed <code>noAssert</code> and no implicit coercion of the offset to <code>uint32</code> anymore.</p></td></tr> 1650<tr><td>v0.11.15</td> 1651<td><p><span>Added in: v0.11.15</span></p></td></tr> 1652</tbody></table> 1653</details> 1654</div> 1655<ul> 1656<li><code>offset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to skip before starting to read. Must 1657satisfy <code>0 <= offset <= buf.length - 8</code>. <strong>Default:</strong> <code>0</code>.</li> 1658<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><number></a></li> 1659</ul> 1660<p>Reads a 64-bit, big-endian double from <code>buf</code> at the specified <code>offset</code>.</p> 1661<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>([<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-number">3</span>, <span class="hljs-number">4</span>, <span class="hljs-number">5</span>, <span class="hljs-number">6</span>, <span class="hljs-number">7</span>, <span class="hljs-number">8</span>]); 1662 1663<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">readDoubleBE</span>(<span class="hljs-number">0</span>)); 1664<span class="hljs-comment">// Prints: 8.20788039913184e-304</span></code></pre> 1665<h4><code>buf.readDoubleLE([offset])</code><span><a class="mark" href="#buffer_buf_readdoublele_offset" id="buffer_buf_readdoublele_offset">#</a></span></h4> 1666<div class="api_metadata"> 1667<details class="changelog"><summary>History</summary> 1668<table> 1669<tbody><tr><th>Version</th><th>Changes</th></tr> 1670<tr><td>v10.0.0</td> 1671<td><p>Removed <code>noAssert</code> and no implicit coercion of the offset to <code>uint32</code> anymore.</p></td></tr> 1672<tr><td>v0.11.15</td> 1673<td><p><span>Added in: v0.11.15</span></p></td></tr> 1674</tbody></table> 1675</details> 1676</div> 1677<ul> 1678<li><code>offset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to skip before starting to read. Must 1679satisfy <code>0 <= offset <= buf.length - 8</code>. <strong>Default:</strong> <code>0</code>.</li> 1680<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><number></a></li> 1681</ul> 1682<p>Reads a 64-bit, little-endian double from <code>buf</code> at the specified <code>offset</code>.</p> 1683<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>([<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-number">3</span>, <span class="hljs-number">4</span>, <span class="hljs-number">5</span>, <span class="hljs-number">6</span>, <span class="hljs-number">7</span>, <span class="hljs-number">8</span>]); 1684 1685<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">readDoubleLE</span>(<span class="hljs-number">0</span>)); 1686<span class="hljs-comment">// Prints: 5.447603722011605e-270</span> 1687<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">readDoubleLE</span>(<span class="hljs-number">1</span>)); 1688<span class="hljs-comment">// Throws ERR_OUT_OF_RANGE.</span></code></pre> 1689<h4><code>buf.readFloatBE([offset])</code><span><a class="mark" href="#buffer_buf_readfloatbe_offset" id="buffer_buf_readfloatbe_offset">#</a></span></h4> 1690<div class="api_metadata"> 1691<details class="changelog"><summary>History</summary> 1692<table> 1693<tbody><tr><th>Version</th><th>Changes</th></tr> 1694<tr><td>v10.0.0</td> 1695<td><p>Removed <code>noAssert</code> and no implicit coercion of the offset to <code>uint32</code> anymore.</p></td></tr> 1696<tr><td>v0.11.15</td> 1697<td><p><span>Added in: v0.11.15</span></p></td></tr> 1698</tbody></table> 1699</details> 1700</div> 1701<ul> 1702<li><code>offset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to skip before starting to read. Must 1703satisfy <code>0 <= offset <= buf.length - 4</code>. <strong>Default:</strong> <code>0</code>.</li> 1704<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><number></a></li> 1705</ul> 1706<p>Reads a 32-bit, big-endian float from <code>buf</code> at the specified <code>offset</code>.</p> 1707<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>([<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-number">3</span>, <span class="hljs-number">4</span>]); 1708 1709<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">readFloatBE</span>(<span class="hljs-number">0</span>)); 1710<span class="hljs-comment">// Prints: 2.387939260590663e-38</span></code></pre> 1711<h4><code>buf.readFloatLE([offset])</code><span><a class="mark" href="#buffer_buf_readfloatle_offset" id="buffer_buf_readfloatle_offset">#</a></span></h4> 1712<div class="api_metadata"> 1713<details class="changelog"><summary>History</summary> 1714<table> 1715<tbody><tr><th>Version</th><th>Changes</th></tr> 1716<tr><td>v10.0.0</td> 1717<td><p>Removed <code>noAssert</code> and no implicit coercion of the offset to <code>uint32</code> anymore.</p></td></tr> 1718<tr><td>v0.11.15</td> 1719<td><p><span>Added in: v0.11.15</span></p></td></tr> 1720</tbody></table> 1721</details> 1722</div> 1723<ul> 1724<li><code>offset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to skip before starting to read. Must 1725satisfy <code>0 <= offset <= buf.length - 4</code>. <strong>Default:</strong> <code>0</code>.</li> 1726<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><number></a></li> 1727</ul> 1728<p>Reads a 32-bit, little-endian float from <code>buf</code> at the specified <code>offset</code>.</p> 1729<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>([<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-number">3</span>, <span class="hljs-number">4</span>]); 1730 1731<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">readFloatLE</span>(<span class="hljs-number">0</span>)); 1732<span class="hljs-comment">// Prints: 1.539989614439558e-36</span> 1733<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">readFloatLE</span>(<span class="hljs-number">1</span>)); 1734<span class="hljs-comment">// Throws ERR_OUT_OF_RANGE.</span></code></pre> 1735<h4><code>buf.readInt8([offset])</code><span><a class="mark" href="#buffer_buf_readint8_offset" id="buffer_buf_readint8_offset">#</a></span></h4> 1736<div class="api_metadata"> 1737<details class="changelog"><summary>History</summary> 1738<table> 1739<tbody><tr><th>Version</th><th>Changes</th></tr> 1740<tr><td>v10.0.0</td> 1741<td><p>Removed <code>noAssert</code> and no implicit coercion of the offset to <code>uint32</code> anymore.</p></td></tr> 1742<tr><td>v0.5.0</td> 1743<td><p><span>Added in: v0.5.0</span></p></td></tr> 1744</tbody></table> 1745</details> 1746</div> 1747<ul> 1748<li><code>offset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to skip before starting to read. Must 1749satisfy <code>0 <= offset <= buf.length - 1</code>. <strong>Default:</strong> <code>0</code>.</li> 1750<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a></li> 1751</ul> 1752<p>Reads a signed 8-bit integer from <code>buf</code> at the specified <code>offset</code>.</p> 1753<p>Integers read from a <code>Buffer</code> are interpreted as two's complement signed values.</p> 1754<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>([-<span class="hljs-number">1</span>, <span class="hljs-number">5</span>]); 1755 1756<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">readInt8</span>(<span class="hljs-number">0</span>)); 1757<span class="hljs-comment">// Prints: -1</span> 1758<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">readInt8</span>(<span class="hljs-number">1</span>)); 1759<span class="hljs-comment">// Prints: 5</span> 1760<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">readInt8</span>(<span class="hljs-number">2</span>)); 1761<span class="hljs-comment">// Throws ERR_OUT_OF_RANGE.</span></code></pre> 1762<h4><code>buf.readInt16BE([offset])</code><span><a class="mark" href="#buffer_buf_readint16be_offset" id="buffer_buf_readint16be_offset">#</a></span></h4> 1763<div class="api_metadata"> 1764<details class="changelog"><summary>History</summary> 1765<table> 1766<tbody><tr><th>Version</th><th>Changes</th></tr> 1767<tr><td>v10.0.0</td> 1768<td><p>Removed <code>noAssert</code> and no implicit coercion of the offset to <code>uint32</code> anymore.</p></td></tr> 1769<tr><td>v0.5.5</td> 1770<td><p><span>Added in: v0.5.5</span></p></td></tr> 1771</tbody></table> 1772</details> 1773</div> 1774<ul> 1775<li><code>offset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to skip before starting to read. Must 1776satisfy <code>0 <= offset <= buf.length - 2</code>. <strong>Default:</strong> <code>0</code>.</li> 1777<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a></li> 1778</ul> 1779<p>Reads a signed, big-endian 16-bit integer from <code>buf</code> at the specified <code>offset</code>.</p> 1780<p>Integers read from a <code>Buffer</code> are interpreted as two's complement signed values.</p> 1781<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>([<span class="hljs-number">0</span>, <span class="hljs-number">5</span>]); 1782 1783<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">readInt16BE</span>(<span class="hljs-number">0</span>)); 1784<span class="hljs-comment">// Prints: 5</span></code></pre> 1785<h4><code>buf.readInt16LE([offset])</code><span><a class="mark" href="#buffer_buf_readint16le_offset" id="buffer_buf_readint16le_offset">#</a></span></h4> 1786<div class="api_metadata"> 1787<details class="changelog"><summary>History</summary> 1788<table> 1789<tbody><tr><th>Version</th><th>Changes</th></tr> 1790<tr><td>v10.0.0</td> 1791<td><p>Removed <code>noAssert</code> and no implicit coercion of the offset to <code>uint32</code> anymore.</p></td></tr> 1792<tr><td>v0.5.5</td> 1793<td><p><span>Added in: v0.5.5</span></p></td></tr> 1794</tbody></table> 1795</details> 1796</div> 1797<ul> 1798<li><code>offset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to skip before starting to read. Must 1799satisfy <code>0 <= offset <= buf.length - 2</code>. <strong>Default:</strong> <code>0</code>.</li> 1800<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a></li> 1801</ul> 1802<p>Reads a signed, little-endian 16-bit integer from <code>buf</code> at the specified 1803<code>offset</code>.</p> 1804<p>Integers read from a <code>Buffer</code> are interpreted as two's complement signed values.</p> 1805<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>([<span class="hljs-number">0</span>, <span class="hljs-number">5</span>]); 1806 1807<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">readInt16LE</span>(<span class="hljs-number">0</span>)); 1808<span class="hljs-comment">// Prints: 1280</span> 1809<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">readInt16LE</span>(<span class="hljs-number">1</span>)); 1810<span class="hljs-comment">// Throws ERR_OUT_OF_RANGE.</span></code></pre> 1811<h4><code>buf.readInt32BE([offset])</code><span><a class="mark" href="#buffer_buf_readint32be_offset" id="buffer_buf_readint32be_offset">#</a></span></h4> 1812<div class="api_metadata"> 1813<details class="changelog"><summary>History</summary> 1814<table> 1815<tbody><tr><th>Version</th><th>Changes</th></tr> 1816<tr><td>v10.0.0</td> 1817<td><p>Removed <code>noAssert</code> and no implicit coercion of the offset to <code>uint32</code> anymore.</p></td></tr> 1818<tr><td>v0.5.5</td> 1819<td><p><span>Added in: v0.5.5</span></p></td></tr> 1820</tbody></table> 1821</details> 1822</div> 1823<ul> 1824<li><code>offset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to skip before starting to read. Must 1825satisfy <code>0 <= offset <= buf.length - 4</code>. <strong>Default:</strong> <code>0</code>.</li> 1826<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a></li> 1827</ul> 1828<p>Reads a signed, big-endian 32-bit integer from <code>buf</code> at the specified <code>offset</code>.</p> 1829<p>Integers read from a <code>Buffer</code> are interpreted as two's complement signed values.</p> 1830<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>([<span class="hljs-number">0</span>, <span class="hljs-number">0</span>, <span class="hljs-number">0</span>, <span class="hljs-number">5</span>]); 1831 1832<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">readInt32BE</span>(<span class="hljs-number">0</span>)); 1833<span class="hljs-comment">// Prints: 5</span></code></pre> 1834<h4><code>buf.readInt32LE([offset])</code><span><a class="mark" href="#buffer_buf_readint32le_offset" id="buffer_buf_readint32le_offset">#</a></span></h4> 1835<div class="api_metadata"> 1836<details class="changelog"><summary>History</summary> 1837<table> 1838<tbody><tr><th>Version</th><th>Changes</th></tr> 1839<tr><td>v10.0.0</td> 1840<td><p>Removed <code>noAssert</code> and no implicit coercion of the offset to <code>uint32</code> anymore.</p></td></tr> 1841<tr><td>v0.5.5</td> 1842<td><p><span>Added in: v0.5.5</span></p></td></tr> 1843</tbody></table> 1844</details> 1845</div> 1846<ul> 1847<li><code>offset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to skip before starting to read. Must 1848satisfy <code>0 <= offset <= buf.length - 4</code>. <strong>Default:</strong> <code>0</code>.</li> 1849<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a></li> 1850</ul> 1851<p>Reads a signed, little-endian 32-bit integer from <code>buf</code> at the specified 1852<code>offset</code>.</p> 1853<p>Integers read from a <code>Buffer</code> are interpreted as two's complement signed values.</p> 1854<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>([<span class="hljs-number">0</span>, <span class="hljs-number">0</span>, <span class="hljs-number">0</span>, <span class="hljs-number">5</span>]); 1855 1856<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">readInt32LE</span>(<span class="hljs-number">0</span>)); 1857<span class="hljs-comment">// Prints: 83886080</span> 1858<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">readInt32LE</span>(<span class="hljs-number">1</span>)); 1859<span class="hljs-comment">// Throws ERR_OUT_OF_RANGE.</span></code></pre> 1860<h4><code>buf.readIntBE(offset, byteLength)</code><span><a class="mark" href="#buffer_buf_readintbe_offset_bytelength" id="buffer_buf_readintbe_offset_bytelength">#</a></span></h4> 1861<div class="api_metadata"> 1862<details class="changelog"><summary>History</summary> 1863<table> 1864<tbody><tr><th>Version</th><th>Changes</th></tr> 1865<tr><td>v10.0.0</td> 1866<td><p>Removed <code>noAssert</code> and no implicit coercion of the offset and <code>byteLength</code> to <code>uint32</code> anymore.</p></td></tr> 1867<tr><td>v0.11.15</td> 1868<td><p><span>Added in: v0.11.15</span></p></td></tr> 1869</tbody></table> 1870</details> 1871</div> 1872<ul> 1873<li><code>offset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to skip before starting to read. Must 1874satisfy <code>0 <= offset <= buf.length - byteLength</code>.</li> 1875<li><code>byteLength</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to read. Must satisfy 1876<code>0 < byteLength <= 6</code>.</li> 1877<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a></li> 1878</ul> 1879<p>Reads <code>byteLength</code> number of bytes from <code>buf</code> at the specified <code>offset</code> 1880and interprets the result as a big-endian, two's complement signed value 1881supporting up to 48 bits of accuracy.</p> 1882<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>([<span class="hljs-number">0x12</span>, <span class="hljs-number">0x34</span>, <span class="hljs-number">0x56</span>, <span class="hljs-number">0x78</span>, <span class="hljs-number">0x90</span>, <span class="hljs-number">0xab</span>]); 1883 1884<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">readIntBE</span>(<span class="hljs-number">0</span>, <span class="hljs-number">6</span>).<span class="hljs-title function_">toString</span>(<span class="hljs-number">16</span>)); 1885<span class="hljs-comment">// Prints: 1234567890ab</span> 1886<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">readIntBE</span>(<span class="hljs-number">1</span>, <span class="hljs-number">6</span>).<span class="hljs-title function_">toString</span>(<span class="hljs-number">16</span>)); 1887<span class="hljs-comment">// Throws ERR_OUT_OF_RANGE.</span> 1888<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">readIntBE</span>(<span class="hljs-number">1</span>, <span class="hljs-number">0</span>).<span class="hljs-title function_">toString</span>(<span class="hljs-number">16</span>)); 1889<span class="hljs-comment">// Throws ERR_OUT_OF_RANGE.</span></code></pre> 1890<h4><code>buf.readIntLE(offset, byteLength)</code><span><a class="mark" href="#buffer_buf_readintle_offset_bytelength" id="buffer_buf_readintle_offset_bytelength">#</a></span></h4> 1891<div class="api_metadata"> 1892<details class="changelog"><summary>History</summary> 1893<table> 1894<tbody><tr><th>Version</th><th>Changes</th></tr> 1895<tr><td>v10.0.0</td> 1896<td><p>Removed <code>noAssert</code> and no implicit coercion of the offset and <code>byteLength</code> to <code>uint32</code> anymore.</p></td></tr> 1897<tr><td>v0.11.15</td> 1898<td><p><span>Added in: v0.11.15</span></p></td></tr> 1899</tbody></table> 1900</details> 1901</div> 1902<ul> 1903<li><code>offset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to skip before starting to read. Must 1904satisfy <code>0 <= offset <= buf.length - byteLength</code>.</li> 1905<li><code>byteLength</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to read. Must satisfy 1906<code>0 < byteLength <= 6</code>.</li> 1907<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a></li> 1908</ul> 1909<p>Reads <code>byteLength</code> number of bytes from <code>buf</code> at the specified <code>offset</code> 1910and interprets the result as a little-endian, two's complement signed value 1911supporting up to 48 bits of accuracy.</p> 1912<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>([<span class="hljs-number">0x12</span>, <span class="hljs-number">0x34</span>, <span class="hljs-number">0x56</span>, <span class="hljs-number">0x78</span>, <span class="hljs-number">0x90</span>, <span class="hljs-number">0xab</span>]); 1913 1914<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">readIntLE</span>(<span class="hljs-number">0</span>, <span class="hljs-number">6</span>).<span class="hljs-title function_">toString</span>(<span class="hljs-number">16</span>)); 1915<span class="hljs-comment">// Prints: -546f87a9cbee</span></code></pre> 1916<h4><code>buf.readUInt8([offset])</code><span><a class="mark" href="#buffer_buf_readuint8_offset" id="buffer_buf_readuint8_offset">#</a></span></h4> 1917<div class="api_metadata"> 1918<details class="changelog"><summary>History</summary> 1919<table> 1920<tbody><tr><th>Version</th><th>Changes</th></tr> 1921<tr><td>v14.9.0</td> 1922<td><p>This function is also available as <code>buf.readUint8()</code>.</p></td></tr> 1923<tr><td>v10.0.0</td> 1924<td><p>Removed <code>noAssert</code> and no implicit coercion of the offset to <code>uint32</code> anymore.</p></td></tr> 1925<tr><td>v0.5.0</td> 1926<td><p><span>Added in: v0.5.0</span></p></td></tr> 1927</tbody></table> 1928</details> 1929</div> 1930<ul> 1931<li><code>offset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to skip before starting to read. Must 1932satisfy <code>0 <= offset <= buf.length - 1</code>. <strong>Default:</strong> <code>0</code>.</li> 1933<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a></li> 1934</ul> 1935<p>Reads an unsigned 8-bit integer from <code>buf</code> at the specified <code>offset</code>.</p> 1936<p>This function is also available under the <code>readUint8</code> alias.</p> 1937<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>([<span class="hljs-number">1</span>, -<span class="hljs-number">2</span>]); 1938 1939<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">readUInt8</span>(<span class="hljs-number">0</span>)); 1940<span class="hljs-comment">// Prints: 1</span> 1941<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">readUInt8</span>(<span class="hljs-number">1</span>)); 1942<span class="hljs-comment">// Prints: 254</span> 1943<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">readUInt8</span>(<span class="hljs-number">2</span>)); 1944<span class="hljs-comment">// Throws ERR_OUT_OF_RANGE.</span></code></pre> 1945<h4><code>buf.readUInt16BE([offset])</code><span><a class="mark" href="#buffer_buf_readuint16be_offset" id="buffer_buf_readuint16be_offset">#</a></span></h4> 1946<div class="api_metadata"> 1947<details class="changelog"><summary>History</summary> 1948<table> 1949<tbody><tr><th>Version</th><th>Changes</th></tr> 1950<tr><td>v14.9.0</td> 1951<td><p>This function is also available as <code>buf.readUint16BE()</code>.</p></td></tr> 1952<tr><td>v10.0.0</td> 1953<td><p>Removed <code>noAssert</code> and no implicit coercion of the offset to <code>uint32</code> anymore.</p></td></tr> 1954<tr><td>v0.5.5</td> 1955<td><p><span>Added in: v0.5.5</span></p></td></tr> 1956</tbody></table> 1957</details> 1958</div> 1959<ul> 1960<li><code>offset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to skip before starting to read. Must 1961satisfy <code>0 <= offset <= buf.length - 2</code>. <strong>Default:</strong> <code>0</code>.</li> 1962<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a></li> 1963</ul> 1964<p>Reads an unsigned, big-endian 16-bit integer from <code>buf</code> at the specified 1965<code>offset</code>.</p> 1966<p>This function is also available under the <code>readUint16BE</code> alias.</p> 1967<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>([<span class="hljs-number">0x12</span>, <span class="hljs-number">0x34</span>, <span class="hljs-number">0x56</span>]); 1968 1969<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">readUInt16BE</span>(<span class="hljs-number">0</span>).<span class="hljs-title function_">toString</span>(<span class="hljs-number">16</span>)); 1970<span class="hljs-comment">// Prints: 1234</span> 1971<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">readUInt16BE</span>(<span class="hljs-number">1</span>).<span class="hljs-title function_">toString</span>(<span class="hljs-number">16</span>)); 1972<span class="hljs-comment">// Prints: 3456</span></code></pre> 1973<h4><code>buf.readUInt16LE([offset])</code><span><a class="mark" href="#buffer_buf_readuint16le_offset" id="buffer_buf_readuint16le_offset">#</a></span></h4> 1974<div class="api_metadata"> 1975<details class="changelog"><summary>History</summary> 1976<table> 1977<tbody><tr><th>Version</th><th>Changes</th></tr> 1978<tr><td>v14.9.0</td> 1979<td><p>This function is also available as <code>buf.readUint16LE()</code>.</p></td></tr> 1980<tr><td>v10.0.0</td> 1981<td><p>Removed <code>noAssert</code> and no implicit coercion of the offset to <code>uint32</code> anymore.</p></td></tr> 1982<tr><td>v0.5.5</td> 1983<td><p><span>Added in: v0.5.5</span></p></td></tr> 1984</tbody></table> 1985</details> 1986</div> 1987<ul> 1988<li><code>offset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to skip before starting to read. Must 1989satisfy <code>0 <= offset <= buf.length - 2</code>. <strong>Default:</strong> <code>0</code>.</li> 1990<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a></li> 1991</ul> 1992<p>Reads an unsigned, little-endian 16-bit integer from <code>buf</code> at the specified 1993<code>offset</code>.</p> 1994<p>This function is also available under the <code>readUint16LE</code> alias.</p> 1995<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>([<span class="hljs-number">0x12</span>, <span class="hljs-number">0x34</span>, <span class="hljs-number">0x56</span>]); 1996 1997<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">readUInt16LE</span>(<span class="hljs-number">0</span>).<span class="hljs-title function_">toString</span>(<span class="hljs-number">16</span>)); 1998<span class="hljs-comment">// Prints: 3412</span> 1999<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">readUInt16LE</span>(<span class="hljs-number">1</span>).<span class="hljs-title function_">toString</span>(<span class="hljs-number">16</span>)); 2000<span class="hljs-comment">// Prints: 5634</span> 2001<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">readUInt16LE</span>(<span class="hljs-number">2</span>).<span class="hljs-title function_">toString</span>(<span class="hljs-number">16</span>)); 2002<span class="hljs-comment">// Throws ERR_OUT_OF_RANGE.</span></code></pre> 2003<h4><code>buf.readUInt32BE([offset])</code><span><a class="mark" href="#buffer_buf_readuint32be_offset" id="buffer_buf_readuint32be_offset">#</a></span></h4> 2004<div class="api_metadata"> 2005<details class="changelog"><summary>History</summary> 2006<table> 2007<tbody><tr><th>Version</th><th>Changes</th></tr> 2008<tr><td>v14.9.0</td> 2009<td><p>This function is also available as <code>buf.readUint32BE()</code>.</p></td></tr> 2010<tr><td>v10.0.0</td> 2011<td><p>Removed <code>noAssert</code> and no implicit coercion of the offset to <code>uint32</code> anymore.</p></td></tr> 2012<tr><td>v0.5.5</td> 2013<td><p><span>Added in: v0.5.5</span></p></td></tr> 2014</tbody></table> 2015</details> 2016</div> 2017<ul> 2018<li><code>offset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to skip before starting to read. Must 2019satisfy <code>0 <= offset <= buf.length - 4</code>. <strong>Default:</strong> <code>0</code>.</li> 2020<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a></li> 2021</ul> 2022<p>Reads an unsigned, big-endian 32-bit integer from <code>buf</code> at the specified 2023<code>offset</code>.</p> 2024<p>This function is also available under the <code>readUint32BE</code> alias.</p> 2025<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>([<span class="hljs-number">0x12</span>, <span class="hljs-number">0x34</span>, <span class="hljs-number">0x56</span>, <span class="hljs-number">0x78</span>]); 2026 2027<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">readUInt32BE</span>(<span class="hljs-number">0</span>).<span class="hljs-title function_">toString</span>(<span class="hljs-number">16</span>)); 2028<span class="hljs-comment">// Prints: 12345678</span></code></pre> 2029<h4><code>buf.readUInt32LE([offset])</code><span><a class="mark" href="#buffer_buf_readuint32le_offset" id="buffer_buf_readuint32le_offset">#</a></span></h4> 2030<div class="api_metadata"> 2031<details class="changelog"><summary>History</summary> 2032<table> 2033<tbody><tr><th>Version</th><th>Changes</th></tr> 2034<tr><td>v14.9.0</td> 2035<td><p>This function is also available as <code>buf.readUint32LE()</code>.</p></td></tr> 2036<tr><td>v10.0.0</td> 2037<td><p>Removed <code>noAssert</code> and no implicit coercion of the offset to <code>uint32</code> anymore.</p></td></tr> 2038<tr><td>v0.5.5</td> 2039<td><p><span>Added in: v0.5.5</span></p></td></tr> 2040</tbody></table> 2041</details> 2042</div> 2043<ul> 2044<li><code>offset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to skip before starting to read. Must 2045satisfy <code>0 <= offset <= buf.length - 4</code>. <strong>Default:</strong> <code>0</code>.</li> 2046<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a></li> 2047</ul> 2048<p>Reads an unsigned, little-endian 32-bit integer from <code>buf</code> at the specified 2049<code>offset</code>.</p> 2050<p>This function is also available under the <code>readUint32LE</code> alias.</p> 2051<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>([<span class="hljs-number">0x12</span>, <span class="hljs-number">0x34</span>, <span class="hljs-number">0x56</span>, <span class="hljs-number">0x78</span>]); 2052 2053<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">readUInt32LE</span>(<span class="hljs-number">0</span>).<span class="hljs-title function_">toString</span>(<span class="hljs-number">16</span>)); 2054<span class="hljs-comment">// Prints: 78563412</span> 2055<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">readUInt32LE</span>(<span class="hljs-number">1</span>).<span class="hljs-title function_">toString</span>(<span class="hljs-number">16</span>)); 2056<span class="hljs-comment">// Throws ERR_OUT_OF_RANGE.</span></code></pre> 2057<h4><code>buf.readUIntBE(offset, byteLength)</code><span><a class="mark" href="#buffer_buf_readuintbe_offset_bytelength" id="buffer_buf_readuintbe_offset_bytelength">#</a></span></h4> 2058<div class="api_metadata"> 2059<details class="changelog"><summary>History</summary> 2060<table> 2061<tbody><tr><th>Version</th><th>Changes</th></tr> 2062<tr><td>v14.9.0</td> 2063<td><p>This function is also available as <code>buf.readUintBE()</code>.</p></td></tr> 2064<tr><td>v10.0.0</td> 2065<td><p>Removed <code>noAssert</code> and no implicit coercion of the offset and <code>byteLength</code> to <code>uint32</code> anymore.</p></td></tr> 2066<tr><td>v0.11.15</td> 2067<td><p><span>Added in: v0.11.15</span></p></td></tr> 2068</tbody></table> 2069</details> 2070</div> 2071<ul> 2072<li><code>offset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to skip before starting to read. Must 2073satisfy <code>0 <= offset <= buf.length - byteLength</code>.</li> 2074<li><code>byteLength</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to read. Must satisfy 2075<code>0 < byteLength <= 6</code>.</li> 2076<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a></li> 2077</ul> 2078<p>Reads <code>byteLength</code> number of bytes from <code>buf</code> at the specified <code>offset</code> 2079and interprets the result as an unsigned big-endian integer supporting 2080up to 48 bits of accuracy.</p> 2081<p>This function is also available under the <code>readUintBE</code> alias.</p> 2082<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>([<span class="hljs-number">0x12</span>, <span class="hljs-number">0x34</span>, <span class="hljs-number">0x56</span>, <span class="hljs-number">0x78</span>, <span class="hljs-number">0x90</span>, <span class="hljs-number">0xab</span>]); 2083 2084<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">readUIntBE</span>(<span class="hljs-number">0</span>, <span class="hljs-number">6</span>).<span class="hljs-title function_">toString</span>(<span class="hljs-number">16</span>)); 2085<span class="hljs-comment">// Prints: 1234567890ab</span> 2086<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">readUIntBE</span>(<span class="hljs-number">1</span>, <span class="hljs-number">6</span>).<span class="hljs-title function_">toString</span>(<span class="hljs-number">16</span>)); 2087<span class="hljs-comment">// Throws ERR_OUT_OF_RANGE.</span></code></pre> 2088<h4><code>buf.readUIntLE(offset, byteLength)</code><span><a class="mark" href="#buffer_buf_readuintle_offset_bytelength" id="buffer_buf_readuintle_offset_bytelength">#</a></span></h4> 2089<div class="api_metadata"> 2090<details class="changelog"><summary>History</summary> 2091<table> 2092<tbody><tr><th>Version</th><th>Changes</th></tr> 2093<tr><td>v14.9.0</td> 2094<td><p>This function is also available as <code>buf.readUintLE()</code>.</p></td></tr> 2095<tr><td>v10.0.0</td> 2096<td><p>Removed <code>noAssert</code> and no implicit coercion of the offset and <code>byteLength</code> to <code>uint32</code> anymore.</p></td></tr> 2097<tr><td>v0.11.15</td> 2098<td><p><span>Added in: v0.11.15</span></p></td></tr> 2099</tbody></table> 2100</details> 2101</div> 2102<ul> 2103<li><code>offset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to skip before starting to read. Must 2104satisfy <code>0 <= offset <= buf.length - byteLength</code>.</li> 2105<li><code>byteLength</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to read. Must satisfy 2106<code>0 < byteLength <= 6</code>.</li> 2107<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a></li> 2108</ul> 2109<p>Reads <code>byteLength</code> number of bytes from <code>buf</code> at the specified <code>offset</code> 2110and interprets the result as an unsigned, little-endian integer supporting 2111up to 48 bits of accuracy.</p> 2112<p>This function is also available under the <code>readUintLE</code> alias.</p> 2113<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>([<span class="hljs-number">0x12</span>, <span class="hljs-number">0x34</span>, <span class="hljs-number">0x56</span>, <span class="hljs-number">0x78</span>, <span class="hljs-number">0x90</span>, <span class="hljs-number">0xab</span>]); 2114 2115<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">readUIntLE</span>(<span class="hljs-number">0</span>, <span class="hljs-number">6</span>).<span class="hljs-title function_">toString</span>(<span class="hljs-number">16</span>)); 2116<span class="hljs-comment">// Prints: ab9078563412</span></code></pre> 2117<h4><code>buf.subarray([start[, end]])</code><span><a class="mark" href="#buffer_buf_subarray_start_end" id="buffer_buf_subarray_start_end">#</a></span></h4> 2118<div class="api_metadata"> 2119<span>Added in: v3.0.0</span> 2120</div> 2121<ul> 2122<li><code>start</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Where the new <code>Buffer</code> will start. <strong>Default:</strong> <code>0</code>.</li> 2123<li><code>end</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Where the new <code>Buffer</code> will end (not inclusive). 2124<strong>Default:</strong> <a href="#buffer_buf_length"><code>buf.length</code></a>.</li> 2125<li>Returns: <a href="buffer.html#buffer_class_buffer" class="type"><Buffer></a></li> 2126</ul> 2127<p>Returns a new <code>Buffer</code> that references the same memory as the original, but 2128offset and cropped by the <code>start</code> and <code>end</code> indices.</p> 2129<p>Specifying <code>end</code> greater than <a href="#buffer_buf_length"><code>buf.length</code></a> will return the same result as 2130that of <code>end</code> equal to <a href="#buffer_buf_length"><code>buf.length</code></a>.</p> 2131<p>This method is inherited from <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray/subarray"><code>TypedArray.prototype.subarray()</code></a>.</p> 2132<p>Modifying the new <code>Buffer</code> slice will modify the memory in the original <code>Buffer</code> 2133because the allocated memory of the two objects overlap.</p> 2134<pre><code class="language-js"><span class="hljs-comment">// Create a `Buffer` with the ASCII alphabet, take a slice, and modify one byte</span> 2135<span class="hljs-comment">// from the original `Buffer`.</span> 2136 2137<span class="hljs-keyword">const</span> buf1 = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">allocUnsafe</span>(<span class="hljs-number">26</span>); 2138 2139<span class="hljs-keyword">for</span> (<span class="hljs-keyword">let</span> i = <span class="hljs-number">0</span>; i < <span class="hljs-number">26</span>; i++) { 2140 <span class="hljs-comment">// 97 is the decimal ASCII value for 'a'.</span> 2141 buf1[i] = i + <span class="hljs-number">97</span>; 2142} 2143 2144<span class="hljs-keyword">const</span> buf2 = buf1.<span class="hljs-title function_">subarray</span>(<span class="hljs-number">0</span>, <span class="hljs-number">3</span>); 2145 2146<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf2.<span class="hljs-title function_">toString</span>(<span class="hljs-string">'ascii'</span>, <span class="hljs-number">0</span>, buf2.<span class="hljs-property">length</span>)); 2147<span class="hljs-comment">// Prints: abc</span> 2148 2149buf1[<span class="hljs-number">0</span>] = <span class="hljs-number">33</span>; 2150 2151<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf2.<span class="hljs-title function_">toString</span>(<span class="hljs-string">'ascii'</span>, <span class="hljs-number">0</span>, buf2.<span class="hljs-property">length</span>)); 2152<span class="hljs-comment">// Prints: !bc</span></code></pre> 2153<p>Specifying negative indexes causes the slice to be generated relative to the 2154end of <code>buf</code> rather than the beginning.</p> 2155<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(<span class="hljs-string">'buffer'</span>); 2156 2157<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">subarray</span>(-<span class="hljs-number">6</span>, -<span class="hljs-number">1</span>).<span class="hljs-title function_">toString</span>()); 2158<span class="hljs-comment">// Prints: buffe</span> 2159<span class="hljs-comment">// (Equivalent to buf.subarray(0, 5).)</span> 2160 2161<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">subarray</span>(-<span class="hljs-number">6</span>, -<span class="hljs-number">2</span>).<span class="hljs-title function_">toString</span>()); 2162<span class="hljs-comment">// Prints: buff</span> 2163<span class="hljs-comment">// (Equivalent to buf.subarray(0, 4).)</span> 2164 2165<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">subarray</span>(-<span class="hljs-number">5</span>, -<span class="hljs-number">2</span>).<span class="hljs-title function_">toString</span>()); 2166<span class="hljs-comment">// Prints: uff</span> 2167<span class="hljs-comment">// (Equivalent to buf.subarray(1, 4).)</span></code></pre> 2168<h4><code>buf.slice([start[, end]])</code><span><a class="mark" href="#buffer_buf_slice_start_end" id="buffer_buf_slice_start_end">#</a></span></h4> 2169<div class="api_metadata"> 2170<details class="changelog"><summary>History</summary> 2171<table> 2172<tbody><tr><th>Version</th><th>Changes</th></tr> 2173<tr><td>v7.0.0</td> 2174<td><p>All offsets are now coerced to integers before doing any calculations with them.</p></td></tr> 2175<tr><td>v7.1.0, v6.9.2</td> 2176<td><p>Coercing the offsets to integers now handles values outside the 32-bit integer range properly.</p></td></tr> 2177<tr><td>v0.3.0</td> 2178<td><p><span>Added in: v0.3.0</span></p></td></tr> 2179</tbody></table> 2180</details> 2181</div> 2182<ul> 2183<li><code>start</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Where the new <code>Buffer</code> will start. <strong>Default:</strong> <code>0</code>.</li> 2184<li><code>end</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Where the new <code>Buffer</code> will end (not inclusive). 2185<strong>Default:</strong> <a href="#buffer_buf_length"><code>buf.length</code></a>.</li> 2186<li>Returns: <a href="buffer.html#buffer_class_buffer" class="type"><Buffer></a></li> 2187</ul> 2188<p>Returns a new <code>Buffer</code> that references the same memory as the original, but 2189offset and cropped by the <code>start</code> and <code>end</code> indices.</p> 2190<p>This is the same behavior as <code>buf.subarray()</code>.</p> 2191<p>This method is not compatible with the <code>Uint8Array.prototype.slice()</code>, 2192which is a superclass of <code>Buffer</code>. To copy the slice, use 2193<code>Uint8Array.prototype.slice()</code>.</p> 2194<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(<span class="hljs-string">'buffer'</span>); 2195 2196<span class="hljs-keyword">const</span> copiedBuf = <span class="hljs-title class_">Uint</span>8<span class="hljs-built_in">Array</span>.<span class="hljs-property"><span class="hljs-keyword">prototype</span></span>.<span class="hljs-property">slice</span>.<span class="hljs-title function_">call</span>(buf); 2197copiedBuf[<span class="hljs-number">0</span>]++; 2198<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(copiedBuf.<span class="hljs-title function_">toString</span>()); 2199<span class="hljs-comment">// Prints: cuffer</span> 2200 2201<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf.<span class="hljs-title function_">toString</span>()); 2202<span class="hljs-comment">// Prints: buffer</span></code></pre> 2203<h4><code>buf.swap16()</code><span><a class="mark" href="#buffer_buf_swap16" id="buffer_buf_swap16">#</a></span></h4> 2204<div class="api_metadata"> 2205<span>Added in: v5.10.0</span> 2206</div> 2207<ul> 2208<li>Returns: <a href="buffer.html#buffer_class_buffer" class="type"><Buffer></a> A reference to <code>buf</code>.</li> 2209</ul> 2210<p>Interprets <code>buf</code> as an array of unsigned 16-bit integers and swaps the 2211byte order <em>in-place</em>. Throws <a href="errors.html#ERR_INVALID_BUFFER_SIZE"><code>ERR_INVALID_BUFFER_SIZE</code></a> if <a href="#buffer_buf_length"><code>buf.length</code></a> 2212is not a multiple of 2.</p> 2213<pre><code class="language-js"><span class="hljs-keyword">const</span> buf1 = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>([<span class="hljs-number">0x1</span>, <span class="hljs-number">0x2</span>, <span class="hljs-number">0x3</span>, <span class="hljs-number">0x4</span>, <span class="hljs-number">0x5</span>, <span class="hljs-number">0x6</span>, <span class="hljs-number">0x7</span>, <span class="hljs-number">0x8</span>]); 2214 2215<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf1); 2216<span class="hljs-comment">// Prints: <Buffer 01 02 03 04 05 06 07 08></span> 2217 2218buf1.<span class="hljs-title function_">swap16</span>(); 2219 2220<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf1); 2221<span class="hljs-comment">// Prints: <Buffer 02 01 04 03 06 05 08 07></span> 2222 2223<span class="hljs-keyword">const</span> buf2 = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>([<span class="hljs-number">0x1</span>, <span class="hljs-number">0x2</span>, <span class="hljs-number">0x3</span>]); 2224 2225buf2.<span class="hljs-title function_">swap16</span>(); 2226<span class="hljs-comment">// Throws ERR_INVALID_BUFFER_SIZE.</span></code></pre> 2227<p>One convenient use of <code>buf.swap16()</code> is to perform a fast in-place conversion 2228between UTF-16 little-endian and UTF-16 big-endian:</p> 2229<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(<span class="hljs-string">'This is little-endian UTF-16'</span>, <span class="hljs-string">'utf16le'</span>); 2230buf.<span class="hljs-title function_">swap16</span>(); <span class="hljs-comment">// Convert to big-endian UTF-16 text.</span></code></pre> 2231<h4><code>buf.swap32()</code><span><a class="mark" href="#buffer_buf_swap32" id="buffer_buf_swap32">#</a></span></h4> 2232<div class="api_metadata"> 2233<span>Added in: v5.10.0</span> 2234</div> 2235<ul> 2236<li>Returns: <a href="buffer.html#buffer_class_buffer" class="type"><Buffer></a> A reference to <code>buf</code>.</li> 2237</ul> 2238<p>Interprets <code>buf</code> as an array of unsigned 32-bit integers and swaps the 2239byte order <em>in-place</em>. Throws <a href="errors.html#ERR_INVALID_BUFFER_SIZE"><code>ERR_INVALID_BUFFER_SIZE</code></a> if <a href="#buffer_buf_length"><code>buf.length</code></a> 2240is not a multiple of 4.</p> 2241<pre><code class="language-js"><span class="hljs-keyword">const</span> buf1 = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>([<span class="hljs-number">0x1</span>, <span class="hljs-number">0x2</span>, <span class="hljs-number">0x3</span>, <span class="hljs-number">0x4</span>, <span class="hljs-number">0x5</span>, <span class="hljs-number">0x6</span>, <span class="hljs-number">0x7</span>, <span class="hljs-number">0x8</span>]); 2242 2243<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf1); 2244<span class="hljs-comment">// Prints: <Buffer 01 02 03 04 05 06 07 08></span> 2245 2246buf1.<span class="hljs-title function_">swap32</span>(); 2247 2248<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf1); 2249<span class="hljs-comment">// Prints: <Buffer 04 03 02 01 08 07 06 05></span> 2250 2251<span class="hljs-keyword">const</span> buf2 = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>([<span class="hljs-number">0x1</span>, <span class="hljs-number">0x2</span>, <span class="hljs-number">0x3</span>]); 2252 2253buf2.<span class="hljs-title function_">swap32</span>(); 2254<span class="hljs-comment">// Throws ERR_INVALID_BUFFER_SIZE.</span></code></pre> 2255<h4><code>buf.swap64()</code><span><a class="mark" href="#buffer_buf_swap64" id="buffer_buf_swap64">#</a></span></h4> 2256<div class="api_metadata"> 2257<span>Added in: v6.3.0</span> 2258</div> 2259<ul> 2260<li>Returns: <a href="buffer.html#buffer_class_buffer" class="type"><Buffer></a> A reference to <code>buf</code>.</li> 2261</ul> 2262<p>Interprets <code>buf</code> as an array of 64-bit numbers and swaps byte order <em>in-place</em>. 2263Throws <a href="errors.html#ERR_INVALID_BUFFER_SIZE"><code>ERR_INVALID_BUFFER_SIZE</code></a> if <a href="#buffer_buf_length"><code>buf.length</code></a> is not a multiple of 8.</p> 2264<pre><code class="language-js"><span class="hljs-keyword">const</span> buf1 = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>([<span class="hljs-number">0x1</span>, <span class="hljs-number">0x2</span>, <span class="hljs-number">0x3</span>, <span class="hljs-number">0x4</span>, <span class="hljs-number">0x5</span>, <span class="hljs-number">0x6</span>, <span class="hljs-number">0x7</span>, <span class="hljs-number">0x8</span>]); 2265 2266<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf1); 2267<span class="hljs-comment">// Prints: <Buffer 01 02 03 04 05 06 07 08></span> 2268 2269buf1.<span class="hljs-title function_">swap64</span>(); 2270 2271<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf1); 2272<span class="hljs-comment">// Prints: <Buffer 08 07 06 05 04 03 02 01></span> 2273 2274<span class="hljs-keyword">const</span> buf2 = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>([<span class="hljs-number">0x1</span>, <span class="hljs-number">0x2</span>, <span class="hljs-number">0x3</span>]); 2275 2276buf2.<span class="hljs-title function_">swap64</span>(); 2277<span class="hljs-comment">// Throws ERR_INVALID_BUFFER_SIZE.</span></code></pre> 2278<h4><code>buf.toJSON()</code><span><a class="mark" href="#buffer_buf_tojson" id="buffer_buf_tojson">#</a></span></h4> 2279<div class="api_metadata"> 2280<span>Added in: v0.9.2</span> 2281</div> 2282<ul> 2283<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a></li> 2284</ul> 2285<p>Returns a JSON representation of <code>buf</code>. <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/stringify"><code>JSON.stringify()</code></a> implicitly calls 2286this function when stringifying a <code>Buffer</code> instance.</p> 2287<p><code>Buffer.from()</code> accepts objects in the format returned from this method. 2288In particular, <code>Buffer.from(buf.toJSON())</code> works like <code>Buffer.from(buf)</code>.</p> 2289<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>([<span class="hljs-number">0x1</span>, <span class="hljs-number">0x2</span>, <span class="hljs-number">0x3</span>, <span class="hljs-number">0x4</span>, <span class="hljs-number">0x5</span>]); 2290<span class="hljs-keyword">const</span> json = <span class="hljs-variable constant_">JSON</span>.<span class="hljs-title function_">stringify</span>(buf); 2291 2292<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(json); 2293<span class="hljs-comment">// Prints: {"type":"Buffer","data":[1,2,3,4,5]}</span> 2294 2295<span class="hljs-keyword">const</span> copy = <span class="hljs-variable constant_">JSON</span>.<span class="hljs-title function_">parse</span>(json, <span class="hljs-function">(<span class="hljs-params">key, value</span>) =></span> { 2296 <span class="hljs-keyword">return</span> value && value.<span class="hljs-property">type</span> === <span class="hljs-string">'Buffer'</span> ? 2297 <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(value) : 2298 value; 2299}); 2300 2301<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(copy); 2302<span class="hljs-comment">// Prints: <Buffer 01 02 03 04 05></span></code></pre> 2303<h4><code>buf.toString([encoding[, start[, end]]])</code><span><a class="mark" href="#buffer_buf_tostring_encoding_start_end" id="buffer_buf_tostring_encoding_start_end">#</a></span></h4> 2304<div class="api_metadata"> 2305<span>Added in: v0.1.90</span> 2306</div> 2307<ul> 2308<li><code>encoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> The character encoding to use. <strong>Default:</strong> <code>'utf8'</code>.</li> 2309<li><code>start</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> The byte offset to start decoding at. <strong>Default:</strong> <code>0</code>.</li> 2310<li><code>end</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> The byte offset to stop decoding at (not inclusive). 2311<strong>Default:</strong> <a href="#buffer_buf_length"><code>buf.length</code></a>.</li> 2312<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a></li> 2313</ul> 2314<p>Decodes <code>buf</code> to a string according to the specified character encoding in 2315<code>encoding</code>. <code>start</code> and <code>end</code> may be passed to decode only a subset of <code>buf</code>.</p> 2316<p>If <code>encoding</code> is <code>'utf8'</code> and a byte sequence in the input is not valid UTF-8, 2317then each invalid byte is replaced with the replacement character <code>U+FFFD</code>.</p> 2318<p>The maximum length of a string instance (in UTF-16 code units) is available 2319as <a href="#buffer_buffer_constants_max_string_length"><code>buffer.constants.MAX_STRING_LENGTH</code></a>.</p> 2320<pre><code class="language-js"><span class="hljs-keyword">const</span> buf1 = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">allocUnsafe</span>(<span class="hljs-number">26</span>); 2321 2322<span class="hljs-keyword">for</span> (<span class="hljs-keyword">let</span> i = <span class="hljs-number">0</span>; i < <span class="hljs-number">26</span>; i++) { 2323 <span class="hljs-comment">// 97 is the decimal ASCII value for 'a'.</span> 2324 buf1[i] = i + <span class="hljs-number">97</span>; 2325} 2326 2327<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf1.<span class="hljs-title function_">toString</span>(<span class="hljs-string">'utf8'</span>)); 2328<span class="hljs-comment">// Prints: abcdefghijklmnopqrstuvwxyz</span> 2329<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf1.<span class="hljs-title function_">toString</span>(<span class="hljs-string">'utf8'</span>, <span class="hljs-number">0</span>, <span class="hljs-number">5</span>)); 2330<span class="hljs-comment">// Prints: abcde</span> 2331 2332<span class="hljs-keyword">const</span> buf2 = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(<span class="hljs-string">'tést'</span>); 2333 2334<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf2.<span class="hljs-title function_">toString</span>(<span class="hljs-string">'hex'</span>)); 2335<span class="hljs-comment">// Prints: 74c3a97374</span> 2336<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf2.<span class="hljs-title function_">toString</span>(<span class="hljs-string">'utf8'</span>, <span class="hljs-number">0</span>, <span class="hljs-number">3</span>)); 2337<span class="hljs-comment">// Prints: té</span> 2338<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf2.<span class="hljs-title function_">toString</span>(<span class="hljs-literal">undefined</span>, <span class="hljs-number">0</span>, <span class="hljs-number">3</span>)); 2339<span class="hljs-comment">// Prints: té</span></code></pre> 2340<h4><code>buf.values()</code><span><a class="mark" href="#buffer_buf_values" id="buffer_buf_values">#</a></span></h4> 2341<div class="api_metadata"> 2342<span>Added in: v1.1.0</span> 2343</div> 2344<ul> 2345<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols#The_iterator_protocol" class="type"><Iterator></a></li> 2346</ul> 2347<p>Creates and returns an <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols">iterator</a> for <code>buf</code> values (bytes). This function is 2348called automatically when a <code>Buffer</code> is used in a <code>for..of</code> statement.</p> 2349<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(<span class="hljs-string">'buffer'</span>); 2350 2351<span class="hljs-keyword">for</span> (<span class="hljs-keyword">const</span> value <span class="hljs-keyword">of</span> buf.<span class="hljs-title function_">values</span>()) { 2352 <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(value); 2353} 2354<span class="hljs-comment">// Prints:</span> 2355<span class="hljs-comment">// 98</span> 2356<span class="hljs-comment">// 117</span> 2357<span class="hljs-comment">// 102</span> 2358<span class="hljs-comment">// 102</span> 2359<span class="hljs-comment">// 101</span> 2360<span class="hljs-comment">// 114</span> 2361 2362<span class="hljs-keyword">for</span> (<span class="hljs-keyword">const</span> value <span class="hljs-keyword">of</span> buf) { 2363 <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(value); 2364} 2365<span class="hljs-comment">// Prints:</span> 2366<span class="hljs-comment">// 98</span> 2367<span class="hljs-comment">// 117</span> 2368<span class="hljs-comment">// 102</span> 2369<span class="hljs-comment">// 102</span> 2370<span class="hljs-comment">// 101</span> 2371<span class="hljs-comment">// 114</span></code></pre> 2372<h4><code>buf.write(string[, offset[, length]][, encoding])</code><span><a class="mark" href="#buffer_buf_write_string_offset_length_encoding" id="buffer_buf_write_string_offset_length_encoding">#</a></span></h4> 2373<div class="api_metadata"> 2374<span>Added in: v0.1.90</span> 2375</div> 2376<ul> 2377<li><code>string</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> String to write to <code>buf</code>.</li> 2378<li><code>offset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to skip before starting to write <code>string</code>. 2379<strong>Default:</strong> <code>0</code>.</li> 2380<li><code>length</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Maximum number of bytes to write (written bytes will not 2381exceed <code>buf.length - offset</code>). <strong>Default:</strong> <code>buf.length - offset</code>.</li> 2382<li><code>encoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> The character encoding of <code>string</code>. <strong>Default:</strong> <code>'utf8'</code>.</li> 2383<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes written.</li> 2384</ul> 2385<p>Writes <code>string</code> to <code>buf</code> at <code>offset</code> according to the character encoding in 2386<code>encoding</code>. The <code>length</code> parameter is the number of bytes to write. If <code>buf</code> did 2387not contain enough space to fit the entire string, only part of <code>string</code> will be 2388written. However, partially encoded characters will not be written.</p> 2389<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">alloc</span>(<span class="hljs-number">256</span>); 2390 2391<span class="hljs-keyword">const</span> len = buf.<span class="hljs-title function_">write</span>(<span class="hljs-string">'\u00bd + \u00bc = \u00be'</span>, <span class="hljs-number">0</span>); 2392 2393<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-string">`<span class="hljs-subst">${len}</span> bytes: <span class="hljs-subst">${buf.toString(<span class="hljs-string">'utf8'</span>, <span class="hljs-number">0</span>, len)}</span>`</span>); 2394<span class="hljs-comment">// Prints: 12 bytes: ½ + ¼ = ¾</span> 2395 2396<span class="hljs-keyword">const</span> buffer = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">alloc</span>(<span class="hljs-number">10</span>); 2397 2398<span class="hljs-keyword">const</span> length = buffer.<span class="hljs-title function_">write</span>(<span class="hljs-string">'abcd'</span>, <span class="hljs-number">8</span>); 2399 2400<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-string">`<span class="hljs-subst">${length}</span> bytes: <span class="hljs-subst">${buffer.toString(<span class="hljs-string">'utf8'</span>, <span class="hljs-number">8</span>, <span class="hljs-number">10</span>)}</span>`</span>); 2401<span class="hljs-comment">// Prints: 2 bytes : ab</span></code></pre> 2402<h4><code>buf.writeBigInt64BE(value[, offset])</code><span><a class="mark" href="#buffer_buf_writebigint64be_value_offset" id="buffer_buf_writebigint64be_value_offset">#</a></span></h4> 2403<div class="api_metadata"> 2404<span>Added in: v12.0.0, v10.20.0</span> 2405</div> 2406<ul> 2407<li><code>value</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/BigInt" class="type"><bigint></a> Number to be written to <code>buf</code>.</li> 2408<li><code>offset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to skip before starting to write. Must 2409satisfy: <code>0 <= offset <= buf.length - 8</code>. <strong>Default:</strong> <code>0</code>.</li> 2410<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> <code>offset</code> plus the number of bytes written.</li> 2411</ul> 2412<p>Writes <code>value</code> to <code>buf</code> at the specified <code>offset</code> as big-endian.</p> 2413<p><code>value</code> is interpreted and written as a two's complement signed integer.</p> 2414<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">allocUnsafe</span>(<span class="hljs-number">8</span>); 2415 2416buf.<span class="hljs-title function_">writeBigInt64BE</span>(<span class="hljs-number">0x0102030405060708n</span>, <span class="hljs-number">0</span>); 2417 2418<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf); 2419<span class="hljs-comment">// Prints: <Buffer 01 02 03 04 05 06 07 08></span></code></pre> 2420<h4><code>buf.writeBigInt64LE(value[, offset])</code><span><a class="mark" href="#buffer_buf_writebigint64le_value_offset" id="buffer_buf_writebigint64le_value_offset">#</a></span></h4> 2421<div class="api_metadata"> 2422<span>Added in: v12.0.0, v10.20.0</span> 2423</div> 2424<ul> 2425<li><code>value</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/BigInt" class="type"><bigint></a> Number to be written to <code>buf</code>.</li> 2426<li><code>offset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to skip before starting to write. Must 2427satisfy: <code>0 <= offset <= buf.length - 8</code>. <strong>Default:</strong> <code>0</code>.</li> 2428<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> <code>offset</code> plus the number of bytes written.</li> 2429</ul> 2430<p>Writes <code>value</code> to <code>buf</code> at the specified <code>offset</code> as little-endian.</p> 2431<p><code>value</code> is interpreted and written as a two's complement signed integer.</p> 2432<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">allocUnsafe</span>(<span class="hljs-number">8</span>); 2433 2434buf.<span class="hljs-title function_">writeBigInt64LE</span>(<span class="hljs-number">0x0102030405060708n</span>, <span class="hljs-number">0</span>); 2435 2436<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf); 2437<span class="hljs-comment">// Prints: <Buffer 08 07 06 05 04 03 02 01></span></code></pre> 2438<h4><code>buf.writeBigUInt64BE(value[, offset])</code><span><a class="mark" href="#buffer_buf_writebiguint64be_value_offset" id="buffer_buf_writebiguint64be_value_offset">#</a></span></h4> 2439<div class="api_metadata"> 2440<details class="changelog"><summary>History</summary> 2441<table> 2442<tbody><tr><th>Version</th><th>Changes</th></tr> 2443<tr><td>v14.10.0</td> 2444<td><p>This function is also available as <code>buf.writeBigUint64BE()</code>.</p></td></tr> 2445<tr><td>v12.0.0, v10.20.0</td> 2446<td><p><span>Added in: v12.0.0, v10.20.0</span></p></td></tr> 2447</tbody></table> 2448</details> 2449</div> 2450<ul> 2451<li><code>value</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/BigInt" class="type"><bigint></a> Number to be written to <code>buf</code>.</li> 2452<li><code>offset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to skip before starting to write. Must 2453satisfy: <code>0 <= offset <= buf.length - 8</code>. <strong>Default:</strong> <code>0</code>.</li> 2454<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> <code>offset</code> plus the number of bytes written.</li> 2455</ul> 2456<p>Writes <code>value</code> to <code>buf</code> at the specified <code>offset</code> as big-endian.</p> 2457<p>This function is also available under the <code>writeBigUint64BE</code> alias.</p> 2458<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">allocUnsafe</span>(<span class="hljs-number">8</span>); 2459 2460buf.<span class="hljs-title function_">writeBigUInt64BE</span>(<span class="hljs-number">0xdecafafecacefaden</span>, <span class="hljs-number">0</span>); 2461 2462<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf); 2463<span class="hljs-comment">// Prints: <Buffer de ca fa fe ca ce fa de></span></code></pre> 2464<h4><code>buf.writeBigUInt64LE(value[, offset])</code><span><a class="mark" href="#buffer_buf_writebiguint64le_value_offset" id="buffer_buf_writebiguint64le_value_offset">#</a></span></h4> 2465<div class="api_metadata"> 2466<details class="changelog"><summary>History</summary> 2467<table> 2468<tbody><tr><th>Version</th><th>Changes</th></tr> 2469<tr><td>v14.10.0</td> 2470<td><p>This function is also available as <code>buf.writeBigUint64LE()</code>.</p></td></tr> 2471<tr><td>v12.0.0, v10.20.0</td> 2472<td><p><span>Added in: v12.0.0, v10.20.0</span></p></td></tr> 2473</tbody></table> 2474</details> 2475</div> 2476<ul> 2477<li><code>value</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/BigInt" class="type"><bigint></a> Number to be written to <code>buf</code>.</li> 2478<li><code>offset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to skip before starting to write. Must 2479satisfy: <code>0 <= offset <= buf.length - 8</code>. <strong>Default:</strong> <code>0</code>.</li> 2480<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> <code>offset</code> plus the number of bytes written.</li> 2481</ul> 2482<p>Writes <code>value</code> to <code>buf</code> at the specified <code>offset</code> as little-endian</p> 2483<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">allocUnsafe</span>(<span class="hljs-number">8</span>); 2484 2485buf.<span class="hljs-title function_">writeBigUInt64LE</span>(<span class="hljs-number">0xdecafafecacefaden</span>, <span class="hljs-number">0</span>); 2486 2487<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf); 2488<span class="hljs-comment">// Prints: <Buffer de fa ce ca fe fa ca de></span></code></pre> 2489<p>This function is also available under the <code>writeBigUint64LE</code> alias.</p> 2490<h4><code>buf.writeDoubleBE(value[, offset])</code><span><a class="mark" href="#buffer_buf_writedoublebe_value_offset" id="buffer_buf_writedoublebe_value_offset">#</a></span></h4> 2491<div class="api_metadata"> 2492<details class="changelog"><summary>History</summary> 2493<table> 2494<tbody><tr><th>Version</th><th>Changes</th></tr> 2495<tr><td>v10.0.0</td> 2496<td><p>Removed <code>noAssert</code> and no implicit coercion of the offset to <code>uint32</code> anymore.</p></td></tr> 2497<tr><td>v0.11.15</td> 2498<td><p><span>Added in: v0.11.15</span></p></td></tr> 2499</tbody></table> 2500</details> 2501</div> 2502<ul> 2503<li><code>value</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><number></a> Number to be written to <code>buf</code>.</li> 2504<li><code>offset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to skip before starting to write. Must 2505satisfy <code>0 <= offset <= buf.length - 8</code>. <strong>Default:</strong> <code>0</code>.</li> 2506<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> <code>offset</code> plus the number of bytes written.</li> 2507</ul> 2508<p>Writes <code>value</code> to <code>buf</code> at the specified <code>offset</code> as big-endian. The <code>value</code> 2509must be a JavaScript number. Behavior is undefined when <code>value</code> is anything 2510other than a JavaScript number.</p> 2511<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">allocUnsafe</span>(<span class="hljs-number">8</span>); 2512 2513buf.<span class="hljs-title function_">writeDoubleBE</span>(<span class="hljs-number">123.456</span>, <span class="hljs-number">0</span>); 2514 2515<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf); 2516<span class="hljs-comment">// Prints: <Buffer 40 5e dd 2f 1a 9f be 77></span></code></pre> 2517<h4><code>buf.writeDoubleLE(value[, offset])</code><span><a class="mark" href="#buffer_buf_writedoublele_value_offset" id="buffer_buf_writedoublele_value_offset">#</a></span></h4> 2518<div class="api_metadata"> 2519<details class="changelog"><summary>History</summary> 2520<table> 2521<tbody><tr><th>Version</th><th>Changes</th></tr> 2522<tr><td>v10.0.0</td> 2523<td><p>Removed <code>noAssert</code> and no implicit coercion of the offset to <code>uint32</code> anymore.</p></td></tr> 2524<tr><td>v0.11.15</td> 2525<td><p><span>Added in: v0.11.15</span></p></td></tr> 2526</tbody></table> 2527</details> 2528</div> 2529<ul> 2530<li><code>value</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><number></a> Number to be written to <code>buf</code>.</li> 2531<li><code>offset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to skip before starting to write. Must 2532satisfy <code>0 <= offset <= buf.length - 8</code>. <strong>Default:</strong> <code>0</code>.</li> 2533<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> <code>offset</code> plus the number of bytes written.</li> 2534</ul> 2535<p>Writes <code>value</code> to <code>buf</code> at the specified <code>offset</code> as little-endian. The <code>value</code> 2536must be a JavaScript number. Behavior is undefined when <code>value</code> is anything 2537other than a JavaScript number.</p> 2538<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">allocUnsafe</span>(<span class="hljs-number">8</span>); 2539 2540buf.<span class="hljs-title function_">writeDoubleLE</span>(<span class="hljs-number">123.456</span>, <span class="hljs-number">0</span>); 2541 2542<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf); 2543<span class="hljs-comment">// Prints: <Buffer 77 be 9f 1a 2f dd 5e 40></span></code></pre> 2544<h4><code>buf.writeFloatBE(value[, offset])</code><span><a class="mark" href="#buffer_buf_writefloatbe_value_offset" id="buffer_buf_writefloatbe_value_offset">#</a></span></h4> 2545<div class="api_metadata"> 2546<details class="changelog"><summary>History</summary> 2547<table> 2548<tbody><tr><th>Version</th><th>Changes</th></tr> 2549<tr><td>v10.0.0</td> 2550<td><p>Removed <code>noAssert</code> and no implicit coercion of the offset to <code>uint32</code> anymore.</p></td></tr> 2551<tr><td>v0.11.15</td> 2552<td><p><span>Added in: v0.11.15</span></p></td></tr> 2553</tbody></table> 2554</details> 2555</div> 2556<ul> 2557<li><code>value</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><number></a> Number to be written to <code>buf</code>.</li> 2558<li><code>offset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to skip before starting to write. Must 2559satisfy <code>0 <= offset <= buf.length - 4</code>. <strong>Default:</strong> <code>0</code>.</li> 2560<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> <code>offset</code> plus the number of bytes written.</li> 2561</ul> 2562<p>Writes <code>value</code> to <code>buf</code> at the specified <code>offset</code> as big-endian. Behavior is 2563undefined when <code>value</code> is anything other than a JavaScript number.</p> 2564<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">allocUnsafe</span>(<span class="hljs-number">4</span>); 2565 2566buf.<span class="hljs-title function_">writeFloatBE</span>(<span class="hljs-number">0xcafebabe</span>, <span class="hljs-number">0</span>); 2567 2568<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf); 2569<span class="hljs-comment">// Prints: <Buffer 4f 4a fe bb></span></code></pre> 2570<h4><code>buf.writeFloatLE(value[, offset])</code><span><a class="mark" href="#buffer_buf_writefloatle_value_offset" id="buffer_buf_writefloatle_value_offset">#</a></span></h4> 2571<div class="api_metadata"> 2572<details class="changelog"><summary>History</summary> 2573<table> 2574<tbody><tr><th>Version</th><th>Changes</th></tr> 2575<tr><td>v10.0.0</td> 2576<td><p>Removed <code>noAssert</code> and no implicit coercion of the offset to <code>uint32</code> anymore.</p></td></tr> 2577<tr><td>v0.11.15</td> 2578<td><p><span>Added in: v0.11.15</span></p></td></tr> 2579</tbody></table> 2580</details> 2581</div> 2582<ul> 2583<li><code>value</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><number></a> Number to be written to <code>buf</code>.</li> 2584<li><code>offset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to skip before starting to write. Must 2585satisfy <code>0 <= offset <= buf.length - 4</code>. <strong>Default:</strong> <code>0</code>.</li> 2586<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> <code>offset</code> plus the number of bytes written.</li> 2587</ul> 2588<p>Writes <code>value</code> to <code>buf</code> at the specified <code>offset</code> as little-endian. Behavior is 2589undefined when <code>value</code> is anything other than a JavaScript number.</p> 2590<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">allocUnsafe</span>(<span class="hljs-number">4</span>); 2591 2592buf.<span class="hljs-title function_">writeFloatLE</span>(<span class="hljs-number">0xcafebabe</span>, <span class="hljs-number">0</span>); 2593 2594<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf); 2595<span class="hljs-comment">// Prints: <Buffer bb fe 4a 4f></span></code></pre> 2596<h4><code>buf.writeInt8(value[, offset])</code><span><a class="mark" href="#buffer_buf_writeint8_value_offset" id="buffer_buf_writeint8_value_offset">#</a></span></h4> 2597<div class="api_metadata"> 2598<details class="changelog"><summary>History</summary> 2599<table> 2600<tbody><tr><th>Version</th><th>Changes</th></tr> 2601<tr><td>v10.0.0</td> 2602<td><p>Removed <code>noAssert</code> and no implicit coercion of the offset to <code>uint32</code> anymore.</p></td></tr> 2603<tr><td>v0.5.0</td> 2604<td><p><span>Added in: v0.5.0</span></p></td></tr> 2605</tbody></table> 2606</details> 2607</div> 2608<ul> 2609<li><code>value</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number to be written to <code>buf</code>.</li> 2610<li><code>offset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to skip before starting to write. Must 2611satisfy <code>0 <= offset <= buf.length - 1</code>. <strong>Default:</strong> <code>0</code>.</li> 2612<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> <code>offset</code> plus the number of bytes written.</li> 2613</ul> 2614<p>Writes <code>value</code> to <code>buf</code> at the specified <code>offset</code>. <code>value</code> must be a valid 2615signed 8-bit integer. Behavior is undefined when <code>value</code> is anything other than 2616a signed 8-bit integer.</p> 2617<p><code>value</code> is interpreted and written as a two's complement signed integer.</p> 2618<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">allocUnsafe</span>(<span class="hljs-number">2</span>); 2619 2620buf.<span class="hljs-title function_">writeInt8</span>(<span class="hljs-number">2</span>, <span class="hljs-number">0</span>); 2621buf.<span class="hljs-title function_">writeInt8</span>(-<span class="hljs-number">2</span>, <span class="hljs-number">1</span>); 2622 2623<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf); 2624<span class="hljs-comment">// Prints: <Buffer 02 fe></span></code></pre> 2625<h4><code>buf.writeInt16BE(value[, offset])</code><span><a class="mark" href="#buffer_buf_writeint16be_value_offset" id="buffer_buf_writeint16be_value_offset">#</a></span></h4> 2626<div class="api_metadata"> 2627<details class="changelog"><summary>History</summary> 2628<table> 2629<tbody><tr><th>Version</th><th>Changes</th></tr> 2630<tr><td>v10.0.0</td> 2631<td><p>Removed <code>noAssert</code> and no implicit coercion of the offset to <code>uint32</code> anymore.</p></td></tr> 2632<tr><td>v0.5.5</td> 2633<td><p><span>Added in: v0.5.5</span></p></td></tr> 2634</tbody></table> 2635</details> 2636</div> 2637<ul> 2638<li><code>value</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number to be written to <code>buf</code>.</li> 2639<li><code>offset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to skip before starting to write. Must 2640satisfy <code>0 <= offset <= buf.length - 2</code>. <strong>Default:</strong> <code>0</code>.</li> 2641<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> <code>offset</code> plus the number of bytes written.</li> 2642</ul> 2643<p>Writes <code>value</code> to <code>buf</code> at the specified <code>offset</code> as big-endian. The <code>value</code> 2644must be a valid signed 16-bit integer. Behavior is undefined when <code>value</code> is 2645anything other than a signed 16-bit integer.</p> 2646<p>The <code>value</code> is interpreted and written as a two's complement signed integer.</p> 2647<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">allocUnsafe</span>(<span class="hljs-number">2</span>); 2648 2649buf.<span class="hljs-title function_">writeInt16BE</span>(<span class="hljs-number">0x0102</span>, <span class="hljs-number">0</span>); 2650 2651<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf); 2652<span class="hljs-comment">// Prints: <Buffer 01 02></span></code></pre> 2653<h4><code>buf.writeInt16LE(value[, offset])</code><span><a class="mark" href="#buffer_buf_writeint16le_value_offset" id="buffer_buf_writeint16le_value_offset">#</a></span></h4> 2654<div class="api_metadata"> 2655<details class="changelog"><summary>History</summary> 2656<table> 2657<tbody><tr><th>Version</th><th>Changes</th></tr> 2658<tr><td>v10.0.0</td> 2659<td><p>Removed <code>noAssert</code> and no implicit coercion of the offset to <code>uint32</code> anymore.</p></td></tr> 2660<tr><td>v0.5.5</td> 2661<td><p><span>Added in: v0.5.5</span></p></td></tr> 2662</tbody></table> 2663</details> 2664</div> 2665<ul> 2666<li><code>value</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number to be written to <code>buf</code>.</li> 2667<li><code>offset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to skip before starting to write. Must 2668satisfy <code>0 <= offset <= buf.length - 2</code>. <strong>Default:</strong> <code>0</code>.</li> 2669<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> <code>offset</code> plus the number of bytes written.</li> 2670</ul> 2671<p>Writes <code>value</code> to <code>buf</code> at the specified <code>offset</code> as little-endian. The <code>value</code> 2672must be a valid signed 16-bit integer. Behavior is undefined when <code>value</code> is 2673anything other than a signed 16-bit integer.</p> 2674<p>The <code>value</code> is interpreted and written as a two's complement signed integer.</p> 2675<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">allocUnsafe</span>(<span class="hljs-number">2</span>); 2676 2677buf.<span class="hljs-title function_">writeInt16LE</span>(<span class="hljs-number">0x0304</span>, <span class="hljs-number">0</span>); 2678 2679<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf); 2680<span class="hljs-comment">// Prints: <Buffer 04 03></span></code></pre> 2681<h4><code>buf.writeInt32BE(value[, offset])</code><span><a class="mark" href="#buffer_buf_writeint32be_value_offset" id="buffer_buf_writeint32be_value_offset">#</a></span></h4> 2682<div class="api_metadata"> 2683<details class="changelog"><summary>History</summary> 2684<table> 2685<tbody><tr><th>Version</th><th>Changes</th></tr> 2686<tr><td>v10.0.0</td> 2687<td><p>Removed <code>noAssert</code> and no implicit coercion of the offset to <code>uint32</code> anymore.</p></td></tr> 2688<tr><td>v0.5.5</td> 2689<td><p><span>Added in: v0.5.5</span></p></td></tr> 2690</tbody></table> 2691</details> 2692</div> 2693<ul> 2694<li><code>value</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number to be written to <code>buf</code>.</li> 2695<li><code>offset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to skip before starting to write. Must 2696satisfy <code>0 <= offset <= buf.length - 4</code>. <strong>Default:</strong> <code>0</code>.</li> 2697<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> <code>offset</code> plus the number of bytes written.</li> 2698</ul> 2699<p>Writes <code>value</code> to <code>buf</code> at the specified <code>offset</code> as big-endian. The <code>value</code> 2700must be a valid signed 32-bit integer. Behavior is undefined when <code>value</code> is 2701anything other than a signed 32-bit integer.</p> 2702<p>The <code>value</code> is interpreted and written as a two's complement signed integer.</p> 2703<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">allocUnsafe</span>(<span class="hljs-number">4</span>); 2704 2705buf.<span class="hljs-title function_">writeInt32BE</span>(<span class="hljs-number">0x01020304</span>, <span class="hljs-number">0</span>); 2706 2707<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf); 2708<span class="hljs-comment">// Prints: <Buffer 01 02 03 04></span></code></pre> 2709<h4><code>buf.writeInt32LE(value[, offset])</code><span><a class="mark" href="#buffer_buf_writeint32le_value_offset" id="buffer_buf_writeint32le_value_offset">#</a></span></h4> 2710<div class="api_metadata"> 2711<details class="changelog"><summary>History</summary> 2712<table> 2713<tbody><tr><th>Version</th><th>Changes</th></tr> 2714<tr><td>v10.0.0</td> 2715<td><p>Removed <code>noAssert</code> and no implicit coercion of the offset to <code>uint32</code> anymore.</p></td></tr> 2716<tr><td>v0.5.5</td> 2717<td><p><span>Added in: v0.5.5</span></p></td></tr> 2718</tbody></table> 2719</details> 2720</div> 2721<ul> 2722<li><code>value</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number to be written to <code>buf</code>.</li> 2723<li><code>offset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to skip before starting to write. Must 2724satisfy <code>0 <= offset <= buf.length - 4</code>. <strong>Default:</strong> <code>0</code>.</li> 2725<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> <code>offset</code> plus the number of bytes written.</li> 2726</ul> 2727<p>Writes <code>value</code> to <code>buf</code> at the specified <code>offset</code> as little-endian. The <code>value</code> 2728must be a valid signed 32-bit integer. Behavior is undefined when <code>value</code> is 2729anything other than a signed 32-bit integer.</p> 2730<p>The <code>value</code> is interpreted and written as a two's complement signed integer.</p> 2731<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">allocUnsafe</span>(<span class="hljs-number">4</span>); 2732 2733buf.<span class="hljs-title function_">writeInt32LE</span>(<span class="hljs-number">0x05060708</span>, <span class="hljs-number">0</span>); 2734 2735<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf); 2736<span class="hljs-comment">// Prints: <Buffer 08 07 06 05></span></code></pre> 2737<h4><code>buf.writeIntBE(value, offset, byteLength)</code><span><a class="mark" href="#buffer_buf_writeintbe_value_offset_bytelength" id="buffer_buf_writeintbe_value_offset_bytelength">#</a></span></h4> 2738<div class="api_metadata"> 2739<details class="changelog"><summary>History</summary> 2740<table> 2741<tbody><tr><th>Version</th><th>Changes</th></tr> 2742<tr><td>v10.0.0</td> 2743<td><p>Removed <code>noAssert</code> and no implicit coercion of the offset and <code>byteLength</code> to <code>uint32</code> anymore.</p></td></tr> 2744<tr><td>v0.11.15</td> 2745<td><p><span>Added in: v0.11.15</span></p></td></tr> 2746</tbody></table> 2747</details> 2748</div> 2749<ul> 2750<li><code>value</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number to be written to <code>buf</code>.</li> 2751<li><code>offset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to skip before starting to write. Must 2752satisfy <code>0 <= offset <= buf.length - byteLength</code>.</li> 2753<li><code>byteLength</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to write. Must satisfy 2754<code>0 < byteLength <= 6</code>.</li> 2755<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> <code>offset</code> plus the number of bytes written.</li> 2756</ul> 2757<p>Writes <code>byteLength</code> bytes of <code>value</code> to <code>buf</code> at the specified <code>offset</code> 2758as big-endian. Supports up to 48 bits of accuracy. Behavior is undefined when 2759<code>value</code> is anything other than a signed integer.</p> 2760<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">allocUnsafe</span>(<span class="hljs-number">6</span>); 2761 2762buf.<span class="hljs-title function_">writeIntBE</span>(<span class="hljs-number">0x1234567890ab</span>, <span class="hljs-number">0</span>, <span class="hljs-number">6</span>); 2763 2764<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf); 2765<span class="hljs-comment">// Prints: <Buffer 12 34 56 78 90 ab></span></code></pre> 2766<h4><code>buf.writeIntLE(value, offset, byteLength)</code><span><a class="mark" href="#buffer_buf_writeintle_value_offset_bytelength" id="buffer_buf_writeintle_value_offset_bytelength">#</a></span></h4> 2767<div class="api_metadata"> 2768<details class="changelog"><summary>History</summary> 2769<table> 2770<tbody><tr><th>Version</th><th>Changes</th></tr> 2771<tr><td>v10.0.0</td> 2772<td><p>Removed <code>noAssert</code> and no implicit coercion of the offset and <code>byteLength</code> to <code>uint32</code> anymore.</p></td></tr> 2773<tr><td>v0.11.15</td> 2774<td><p><span>Added in: v0.11.15</span></p></td></tr> 2775</tbody></table> 2776</details> 2777</div> 2778<ul> 2779<li><code>value</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number to be written to <code>buf</code>.</li> 2780<li><code>offset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to skip before starting to write. Must 2781satisfy <code>0 <= offset <= buf.length - byteLength</code>.</li> 2782<li><code>byteLength</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to write. Must satisfy 2783<code>0 < byteLength <= 6</code>.</li> 2784<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> <code>offset</code> plus the number of bytes written.</li> 2785</ul> 2786<p>Writes <code>byteLength</code> bytes of <code>value</code> to <code>buf</code> at the specified <code>offset</code> 2787as little-endian. Supports up to 48 bits of accuracy. Behavior is undefined 2788when <code>value</code> is anything other than a signed integer.</p> 2789<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">allocUnsafe</span>(<span class="hljs-number">6</span>); 2790 2791buf.<span class="hljs-title function_">writeIntLE</span>(<span class="hljs-number">0x1234567890ab</span>, <span class="hljs-number">0</span>, <span class="hljs-number">6</span>); 2792 2793<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf); 2794<span class="hljs-comment">// Prints: <Buffer ab 90 78 56 34 12></span></code></pre> 2795<h4><code>buf.writeUInt8(value[, offset])</code><span><a class="mark" href="#buffer_buf_writeuint8_value_offset" id="buffer_buf_writeuint8_value_offset">#</a></span></h4> 2796<div class="api_metadata"> 2797<details class="changelog"><summary>History</summary> 2798<table> 2799<tbody><tr><th>Version</th><th>Changes</th></tr> 2800<tr><td>v14.9.0</td> 2801<td><p>This function is also available as <code>buf.writeUint8()</code>.</p></td></tr> 2802<tr><td>v10.0.0</td> 2803<td><p>Removed <code>noAssert</code> and no implicit coercion of the offset to <code>uint32</code> anymore.</p></td></tr> 2804<tr><td>v0.5.0</td> 2805<td><p><span>Added in: v0.5.0</span></p></td></tr> 2806</tbody></table> 2807</details> 2808</div> 2809<ul> 2810<li><code>value</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number to be written to <code>buf</code>.</li> 2811<li><code>offset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to skip before starting to write. Must 2812satisfy <code>0 <= offset <= buf.length - 1</code>. <strong>Default:</strong> <code>0</code>.</li> 2813<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> <code>offset</code> plus the number of bytes written.</li> 2814</ul> 2815<p>Writes <code>value</code> to <code>buf</code> at the specified <code>offset</code>. <code>value</code> must be a 2816valid unsigned 8-bit integer. Behavior is undefined when <code>value</code> is anything 2817other than an unsigned 8-bit integer.</p> 2818<p>This function is also available under the <code>writeUint8</code> alias.</p> 2819<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">allocUnsafe</span>(<span class="hljs-number">4</span>); 2820 2821buf.<span class="hljs-title function_">writeUInt8</span>(<span class="hljs-number">0x3</span>, <span class="hljs-number">0</span>); 2822buf.<span class="hljs-title function_">writeUInt8</span>(<span class="hljs-number">0x4</span>, <span class="hljs-number">1</span>); 2823buf.<span class="hljs-title function_">writeUInt8</span>(<span class="hljs-number">0x23</span>, <span class="hljs-number">2</span>); 2824buf.<span class="hljs-title function_">writeUInt8</span>(<span class="hljs-number">0x42</span>, <span class="hljs-number">3</span>); 2825 2826<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf); 2827<span class="hljs-comment">// Prints: <Buffer 03 04 23 42></span></code></pre> 2828<h4><code>buf.writeUInt16BE(value[, offset])</code><span><a class="mark" href="#buffer_buf_writeuint16be_value_offset" id="buffer_buf_writeuint16be_value_offset">#</a></span></h4> 2829<div class="api_metadata"> 2830<details class="changelog"><summary>History</summary> 2831<table> 2832<tbody><tr><th>Version</th><th>Changes</th></tr> 2833<tr><td>v14.9.0</td> 2834<td><p>This function is also available as <code>buf.writeUint16BE()</code>.</p></td></tr> 2835<tr><td>v10.0.0</td> 2836<td><p>Removed <code>noAssert</code> and no implicit coercion of the offset to <code>uint32</code> anymore.</p></td></tr> 2837<tr><td>v0.5.5</td> 2838<td><p><span>Added in: v0.5.5</span></p></td></tr> 2839</tbody></table> 2840</details> 2841</div> 2842<ul> 2843<li><code>value</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number to be written to <code>buf</code>.</li> 2844<li><code>offset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to skip before starting to write. Must 2845satisfy <code>0 <= offset <= buf.length - 2</code>. <strong>Default:</strong> <code>0</code>.</li> 2846<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> <code>offset</code> plus the number of bytes written.</li> 2847</ul> 2848<p>Writes <code>value</code> to <code>buf</code> at the specified <code>offset</code> as big-endian. The <code>value</code> 2849must be a valid unsigned 16-bit integer. Behavior is undefined when <code>value</code> 2850is anything other than an unsigned 16-bit integer.</p> 2851<p>This function is also available under the <code>writeUint16BE</code> alias.</p> 2852<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">allocUnsafe</span>(<span class="hljs-number">4</span>); 2853 2854buf.<span class="hljs-title function_">writeUInt16BE</span>(<span class="hljs-number">0xdead</span>, <span class="hljs-number">0</span>); 2855buf.<span class="hljs-title function_">writeUInt16BE</span>(<span class="hljs-number">0xbeef</span>, <span class="hljs-number">2</span>); 2856 2857<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf); 2858<span class="hljs-comment">// Prints: <Buffer de ad be ef></span></code></pre> 2859<h4><code>buf.writeUInt16LE(value[, offset])</code><span><a class="mark" href="#buffer_buf_writeuint16le_value_offset" id="buffer_buf_writeuint16le_value_offset">#</a></span></h4> 2860<div class="api_metadata"> 2861<details class="changelog"><summary>History</summary> 2862<table> 2863<tbody><tr><th>Version</th><th>Changes</th></tr> 2864<tr><td>v14.9.0, v12.19.0</td> 2865<td><p>This function is also available as <code>buf.writeUint16LE()</code>.</p></td></tr> 2866<tr><td>v10.0.0</td> 2867<td><p>Removed <code>noAssert</code> and no implicit coercion of the offset to <code>uint32</code> anymore.</p></td></tr> 2868<tr><td>v0.5.5</td> 2869<td><p><span>Added in: v0.5.5</span></p></td></tr> 2870</tbody></table> 2871</details> 2872</div> 2873<ul> 2874<li><code>value</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number to be written to <code>buf</code>.</li> 2875<li><code>offset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to skip before starting to write. Must 2876satisfy <code>0 <= offset <= buf.length - 2</code>. <strong>Default:</strong> <code>0</code>.</li> 2877<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> <code>offset</code> plus the number of bytes written.</li> 2878</ul> 2879<p>Writes <code>value</code> to <code>buf</code> at the specified <code>offset</code> as little-endian. The <code>value</code> 2880must be a valid unsigned 16-bit integer. Behavior is undefined when <code>value</code> is 2881anything other than an unsigned 16-bit integer.</p> 2882<p>This function is also available under the <code>writeUint16LE</code> alias.</p> 2883<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">allocUnsafe</span>(<span class="hljs-number">4</span>); 2884 2885buf.<span class="hljs-title function_">writeUInt16LE</span>(<span class="hljs-number">0xdead</span>, <span class="hljs-number">0</span>); 2886buf.<span class="hljs-title function_">writeUInt16LE</span>(<span class="hljs-number">0xbeef</span>, <span class="hljs-number">2</span>); 2887 2888<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf); 2889<span class="hljs-comment">// Prints: <Buffer ad de ef be></span></code></pre> 2890<h4><code>buf.writeUInt32BE(value[, offset])</code><span><a class="mark" href="#buffer_buf_writeuint32be_value_offset" id="buffer_buf_writeuint32be_value_offset">#</a></span></h4> 2891<div class="api_metadata"> 2892<details class="changelog"><summary>History</summary> 2893<table> 2894<tbody><tr><th>Version</th><th>Changes</th></tr> 2895<tr><td>v14.9.0</td> 2896<td><p>This function is also available as <code>buf.writeUint32BE()</code>.</p></td></tr> 2897<tr><td>v10.0.0</td> 2898<td><p>Removed <code>noAssert</code> and no implicit coercion of the offset to <code>uint32</code> anymore.</p></td></tr> 2899<tr><td>v0.5.5</td> 2900<td><p><span>Added in: v0.5.5</span></p></td></tr> 2901</tbody></table> 2902</details> 2903</div> 2904<ul> 2905<li><code>value</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number to be written to <code>buf</code>.</li> 2906<li><code>offset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to skip before starting to write. Must 2907satisfy <code>0 <= offset <= buf.length - 4</code>. <strong>Default:</strong> <code>0</code>.</li> 2908<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> <code>offset</code> plus the number of bytes written.</li> 2909</ul> 2910<p>Writes <code>value</code> to <code>buf</code> at the specified <code>offset</code> as big-endian. The <code>value</code> 2911must be a valid unsigned 32-bit integer. Behavior is undefined when <code>value</code> 2912is anything other than an unsigned 32-bit integer.</p> 2913<p>This function is also available under the <code>writeUint32BE</code> alias.</p> 2914<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">allocUnsafe</span>(<span class="hljs-number">4</span>); 2915 2916buf.<span class="hljs-title function_">writeUInt32BE</span>(<span class="hljs-number">0xfeedface</span>, <span class="hljs-number">0</span>); 2917 2918<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf); 2919<span class="hljs-comment">// Prints: <Buffer fe ed fa ce></span></code></pre> 2920<h4><code>buf.writeUInt32LE(value[, offset])</code><span><a class="mark" href="#buffer_buf_writeuint32le_value_offset" id="buffer_buf_writeuint32le_value_offset">#</a></span></h4> 2921<div class="api_metadata"> 2922<details class="changelog"><summary>History</summary> 2923<table> 2924<tbody><tr><th>Version</th><th>Changes</th></tr> 2925<tr><td>v14.9.0</td> 2926<td><p>This function is also available as <code>buf.writeUint32LE()</code>.</p></td></tr> 2927<tr><td>v10.0.0</td> 2928<td><p>Removed <code>noAssert</code> and no implicit coercion of the offset to <code>uint32</code> anymore.</p></td></tr> 2929<tr><td>v0.5.5</td> 2930<td><p><span>Added in: v0.5.5</span></p></td></tr> 2931</tbody></table> 2932</details> 2933</div> 2934<ul> 2935<li><code>value</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number to be written to <code>buf</code>.</li> 2936<li><code>offset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to skip before starting to write. Must 2937satisfy <code>0 <= offset <= buf.length - 4</code>. <strong>Default:</strong> <code>0</code>.</li> 2938<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> <code>offset</code> plus the number of bytes written.</li> 2939</ul> 2940<p>Writes <code>value</code> to <code>buf</code> at the specified <code>offset</code> as little-endian. The <code>value</code> 2941must be a valid unsigned 32-bit integer. Behavior is undefined when <code>value</code> is 2942anything other than an unsigned 32-bit integer.</p> 2943<p>This function is also available under the <code>writeUint32LE</code> alias.</p> 2944<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">allocUnsafe</span>(<span class="hljs-number">4</span>); 2945 2946buf.<span class="hljs-title function_">writeUInt32LE</span>(<span class="hljs-number">0xfeedface</span>, <span class="hljs-number">0</span>); 2947 2948<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf); 2949<span class="hljs-comment">// Prints: <Buffer ce fa ed fe></span></code></pre> 2950<h4><code>buf.writeUIntBE(value, offset, byteLength)</code><span><a class="mark" href="#buffer_buf_writeuintbe_value_offset_bytelength" id="buffer_buf_writeuintbe_value_offset_bytelength">#</a></span></h4> 2951<div class="api_metadata"> 2952<details class="changelog"><summary>History</summary> 2953<table> 2954<tbody><tr><th>Version</th><th>Changes</th></tr> 2955<tr><td>v14.9.0</td> 2956<td><p>This function is also available as <code>buf.writeUintBE()</code>.</p></td></tr> 2957<tr><td>v10.0.0</td> 2958<td><p>Removed <code>noAssert</code> and no implicit coercion of the offset and <code>byteLength</code> to <code>uint32</code> anymore.</p></td></tr> 2959<tr><td>v0.5.5</td> 2960<td><p><span>Added in: v0.5.5</span></p></td></tr> 2961</tbody></table> 2962</details> 2963</div> 2964<ul> 2965<li><code>value</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number to be written to <code>buf</code>.</li> 2966<li><code>offset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to skip before starting to write. Must 2967satisfy <code>0 <= offset <= buf.length - byteLength</code>.</li> 2968<li><code>byteLength</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to write. Must satisfy 2969<code>0 < byteLength <= 6</code>.</li> 2970<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> <code>offset</code> plus the number of bytes written.</li> 2971</ul> 2972<p>Writes <code>byteLength</code> bytes of <code>value</code> to <code>buf</code> at the specified <code>offset</code> 2973as big-endian. Supports up to 48 bits of accuracy. Behavior is undefined 2974when <code>value</code> is anything other than an unsigned integer.</p> 2975<p>This function is also available under the <code>writeUintBE</code> alias.</p> 2976<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">allocUnsafe</span>(<span class="hljs-number">6</span>); 2977 2978buf.<span class="hljs-title function_">writeUIntBE</span>(<span class="hljs-number">0x1234567890ab</span>, <span class="hljs-number">0</span>, <span class="hljs-number">6</span>); 2979 2980<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf); 2981<span class="hljs-comment">// Prints: <Buffer 12 34 56 78 90 ab></span></code></pre> 2982<h4><code>buf.writeUIntLE(value, offset, byteLength)</code><span><a class="mark" href="#buffer_buf_writeuintle_value_offset_bytelength" id="buffer_buf_writeuintle_value_offset_bytelength">#</a></span></h4> 2983<div class="api_metadata"> 2984<details class="changelog"><summary>History</summary> 2985<table> 2986<tbody><tr><th>Version</th><th>Changes</th></tr> 2987<tr><td>v14.9.0</td> 2988<td><p>This function is also available as <code>buf.writeUintLE()</code>.</p></td></tr> 2989<tr><td>v10.0.0</td> 2990<td><p>Removed <code>noAssert</code> and no implicit coercion of the offset and <code>byteLength</code> to <code>uint32</code> anymore.</p></td></tr> 2991<tr><td>v0.5.5</td> 2992<td><p><span>Added in: v0.5.5</span></p></td></tr> 2993</tbody></table> 2994</details> 2995</div> 2996<ul> 2997<li><code>value</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number to be written to <code>buf</code>.</li> 2998<li><code>offset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to skip before starting to write. Must 2999satisfy <code>0 <= offset <= buf.length - byteLength</code>.</li> 3000<li><code>byteLength</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to write. Must satisfy 3001<code>0 < byteLength <= 6</code>.</li> 3002<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> <code>offset</code> plus the number of bytes written.</li> 3003</ul> 3004<p>Writes <code>byteLength</code> bytes of <code>value</code> to <code>buf</code> at the specified <code>offset</code> 3005as little-endian. Supports up to 48 bits of accuracy. Behavior is undefined 3006when <code>value</code> is anything other than an unsigned integer.</p> 3007<p>This function is also available under the <code>writeUintLE</code> alias.</p> 3008<pre><code class="language-js"><span class="hljs-keyword">const</span> buf = <span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">allocUnsafe</span>(<span class="hljs-number">6</span>); 3009 3010buf.<span class="hljs-title function_">writeUIntLE</span>(<span class="hljs-number">0x1234567890ab</span>, <span class="hljs-number">0</span>, <span class="hljs-number">6</span>); 3011 3012<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(buf); 3013<span class="hljs-comment">// Prints: <Buffer ab 90 78 56 34 12></span></code></pre> 3014<h4><code>new Buffer(array)</code><span><a class="mark" href="#buffer_new_buffer_array" id="buffer_new_buffer_array">#</a></span></h4> 3015<div class="api_metadata"> 3016<details class="changelog"><summary>History</summary> 3017<table> 3018<tbody><tr><th>Version</th><th>Changes</th></tr> 3019<tr><td>v10.0.0</td> 3020<td><p>Calling this constructor emits a deprecation warning when run from code outside the <code>node_modules</code> directory.</p></td></tr> 3021<tr><td>v7.2.1</td> 3022<td><p>Calling this constructor no longer emits a deprecation warning.</p></td></tr> 3023<tr><td>v7.0.0</td> 3024<td><p>Calling this constructor emits a deprecation warning now.</p></td></tr> 3025<tr><td>v6.0.0</td> 3026<td><p><span>Deprecated since: v6.0.0</span></p></td></tr> 3027</tbody></table> 3028</details> 3029</div> 3030<p></p><div class="api_stability api_stability_0"><a href="documentation.html#documentation_stability_index">Stability: 0</a> - Deprecated: Use <a href="#buffer_static_method_buffer_from_array"><code>Buffer.from(array)</code></a> instead.</div><p></p> 3031<ul> 3032<li><code>array</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer[]></a> An array of bytes to copy from.</li> 3033</ul> 3034<p>See <a href="#buffer_static_method_buffer_from_array"><code>Buffer.from(array)</code></a>.</p> 3035<h4><code>new Buffer(arrayBuffer[, byteOffset[, length]])</code><span><a class="mark" href="#buffer_new_buffer_arraybuffer_byteoffset_length" id="buffer_new_buffer_arraybuffer_byteoffset_length">#</a></span></h4> 3036<div class="api_metadata"> 3037<details class="changelog"><summary>History</summary> 3038<table> 3039<tbody><tr><th>Version</th><th>Changes</th></tr> 3040<tr><td>v10.0.0</td> 3041<td><p>Calling this constructor emits a deprecation warning when run from code outside the <code>node_modules</code> directory.</p></td></tr> 3042<tr><td>v7.2.1</td> 3043<td><p>Calling this constructor no longer emits a deprecation warning.</p></td></tr> 3044<tr><td>v7.0.0</td> 3045<td><p>Calling this constructor emits a deprecation warning now.</p></td></tr> 3046<tr><td>v6.0.0</td> 3047<td><p>The <code>byteOffset</code> and <code>length</code> parameters are supported now.</p></td></tr> 3048<tr><td>v6.0.0</td> 3049<td><p><span>Deprecated since: v6.0.0</span></p></td></tr> 3050<tr><td>v3.0.0</td> 3051<td><p><span>Added in: v3.0.0</span></p></td></tr> 3052</tbody></table> 3053</details> 3054</div> 3055<p></p><div class="api_stability api_stability_0"><a href="documentation.html#documentation_stability_index">Stability: 0</a> - Deprecated: Use 3056<a href="#buffer_static_method_buffer_from_arraybuffer_byteoffset_length"><code>Buffer.from(arrayBuffer[, byteOffset[, length]])</code></a> 3057instead.</div><p></p> 3058<ul> 3059<li><code>arrayBuffer</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/ArrayBuffer" class="type"><ArrayBuffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/SharedArrayBuffer" class="type"><SharedArrayBuffer></a> An <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/ArrayBuffer"><code>ArrayBuffer</code></a>, 3060<a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/SharedArrayBuffer"><code>SharedArrayBuffer</code></a> or the <code>.buffer</code> property of a <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray"><code>TypedArray</code></a>.</li> 3061<li><code>byteOffset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Index of first byte to expose. <strong>Default:</strong> <code>0</code>.</li> 3062<li><code>length</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Number of bytes to expose. 3063<strong>Default:</strong> <code>arrayBuffer.byteLength - byteOffset</code>.</li> 3064</ul> 3065<p>See 3066<a href="#buffer_static_method_buffer_from_arraybuffer_byteoffset_length"><code>Buffer.from(arrayBuffer[, byteOffset[, length]])</code></a>.</p> 3067<h4><code>new Buffer(buffer)</code><span><a class="mark" href="#buffer_new_buffer_buffer" id="buffer_new_buffer_buffer">#</a></span></h4> 3068<div class="api_metadata"> 3069<details class="changelog"><summary>History</summary> 3070<table> 3071<tbody><tr><th>Version</th><th>Changes</th></tr> 3072<tr><td>v10.0.0</td> 3073<td><p>Calling this constructor emits a deprecation warning when run from code outside the <code>node_modules</code> directory.</p></td></tr> 3074<tr><td>v7.2.1</td> 3075<td><p>Calling this constructor no longer emits a deprecation warning.</p></td></tr> 3076<tr><td>v7.0.0</td> 3077<td><p>Calling this constructor emits a deprecation warning now.</p></td></tr> 3078<tr><td>v6.0.0</td> 3079<td><p><span>Deprecated since: v6.0.0</span></p></td></tr> 3080</tbody></table> 3081</details> 3082</div> 3083<p></p><div class="api_stability api_stability_0"><a href="documentation.html#documentation_stability_index">Stability: 0</a> - Deprecated: Use <a href="#buffer_static_method_buffer_from_buffer"><code>Buffer.from(buffer)</code></a> instead.</div><p></p> 3084<ul> 3085<li><code>buffer</code> <a href="buffer.html#buffer_class_buffer" class="type"><Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Uint8Array" class="type"><Uint8Array></a> An existing <code>Buffer</code> or <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Uint8Array"><code>Uint8Array</code></a> from 3086which to copy data.</li> 3087</ul> 3088<p>See <a href="#buffer_static_method_buffer_from_buffer"><code>Buffer.from(buffer)</code></a>.</p> 3089<h4><code>new Buffer(size)</code><span><a class="mark" href="#buffer_new_buffer_size" id="buffer_new_buffer_size">#</a></span></h4> 3090<div class="api_metadata"> 3091<details class="changelog"><summary>History</summary> 3092<table> 3093<tbody><tr><th>Version</th><th>Changes</th></tr> 3094<tr><td>v10.0.0</td> 3095<td><p>Calling this constructor emits a deprecation warning when run from code outside the <code>node_modules</code> directory.</p></td></tr> 3096<tr><td>v8.0.0</td> 3097<td><p>The <code>new Buffer(size)</code> will return zero-filled memory by default.</p></td></tr> 3098<tr><td>v7.2.1</td> 3099<td><p>Calling this constructor no longer emits a deprecation warning.</p></td></tr> 3100<tr><td>v7.0.0</td> 3101<td><p>Calling this constructor emits a deprecation warning now.</p></td></tr> 3102<tr><td>v6.0.0</td> 3103<td><p><span>Deprecated since: v6.0.0</span></p></td></tr> 3104</tbody></table> 3105</details> 3106</div> 3107<p></p><div class="api_stability api_stability_0"><a href="documentation.html#documentation_stability_index">Stability: 0</a> - Deprecated: Use <a href="#buffer_static_method_buffer_alloc_size_fill_encoding"><code>Buffer.alloc()</code></a> instead (also see 3108<a href="#buffer_static_method_buffer_allocunsafe_size"><code>Buffer.allocUnsafe()</code></a>).</div><p></p> 3109<ul> 3110<li><code>size</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> The desired length of the new <code>Buffer</code>.</li> 3111</ul> 3112<p>See <a href="#buffer_static_method_buffer_alloc_size_fill_encoding"><code>Buffer.alloc()</code></a> and <a href="#buffer_static_method_buffer_allocunsafe_size"><code>Buffer.allocUnsafe()</code></a>. This variant of the 3113constructor is equivalent to <a href="#buffer_static_method_buffer_alloc_size_fill_encoding"><code>Buffer.alloc()</code></a>.</p> 3114<h4><code>new Buffer(string[, encoding])</code><span><a class="mark" href="#buffer_new_buffer_string_encoding" id="buffer_new_buffer_string_encoding">#</a></span></h4> 3115<div class="api_metadata"> 3116<details class="changelog"><summary>History</summary> 3117<table> 3118<tbody><tr><th>Version</th><th>Changes</th></tr> 3119<tr><td>v10.0.0</td> 3120<td><p>Calling this constructor emits a deprecation warning when run from code outside the <code>node_modules</code> directory.</p></td></tr> 3121<tr><td>v7.2.1</td> 3122<td><p>Calling this constructor no longer emits a deprecation warning.</p></td></tr> 3123<tr><td>v7.0.0</td> 3124<td><p>Calling this constructor emits a deprecation warning now.</p></td></tr> 3125<tr><td>v6.0.0</td> 3126<td><p><span>Deprecated since: v6.0.0</span></p></td></tr> 3127</tbody></table> 3128</details> 3129</div> 3130<p></p><div class="api_stability api_stability_0"><a href="documentation.html#documentation_stability_index">Stability: 0</a> - Deprecated: 3131Use <a href="#buffer_static_method_buffer_from_string_encoding"><code>Buffer.from(string[, encoding])</code></a> instead.</div><p></p> 3132<ul> 3133<li><code>string</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> String to encode.</li> 3134<li><code>encoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> The encoding of <code>string</code>. <strong>Default:</strong> <code>'utf8'</code>.</li> 3135</ul> 3136<p>See <a href="#buffer_static_method_buffer_from_string_encoding"><code>Buffer.from(string[, encoding])</code></a>.</p> 3137</section><section><h3><code>buffer</code> module APIs<span><a class="mark" href="#buffer_buffer_module_apis" id="buffer_buffer_module_apis">#</a></span></h3> 3138<p>While, the <code>Buffer</code> object is available as a global, there are additional 3139<code>Buffer</code>-related APIs that are available only via the <code>buffer</code> module 3140accessed using <code>require('buffer')</code>.</p> 3141<h4><code>buffer.atob(data)</code><span><a class="mark" href="#buffer_buffer_atob_data" id="buffer_buffer_atob_data">#</a></span></h4> 3142<div class="api_metadata"> 3143<span>Added in: v14.17.0</span> 3144</div> 3145<ul> 3146<li><code>data</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type"><any></a> The Base64-encoded input string.</li> 3147</ul> 3148<p>Decodes a string of Base64-encoded data into bytes, and encodes those bytes 3149into a string using Latin-1 (ISO-8859-1).</p> 3150<p>The <code>data</code> may be any JavaScript-value that can be coerced into a string.</p> 3151<p><strong>This function is only provided for compatibility with legacy web platform APIs 3152and should never be used in new code, because they use strings to represent 3153binary data and predate the introduction of typed arrays in JavaScript. 3154For code running using Node.js APIs, converting between base64-encoded strings 3155and binary data should be performed using <code>Buffer.from(str, 'base64')</code> and 3156<code>buf.toString('base64')</code>.</strong></p> 3157<h4><code>buffer.btoa(data)</code><span><a class="mark" href="#buffer_buffer_btoa_data" id="buffer_buffer_btoa_data">#</a></span></h4> 3158<div class="api_metadata"> 3159<span>Added in: v14.17.0</span> 3160</div> 3161<ul> 3162<li><code>data</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type"><any></a> An ASCII (Latin1) string.</li> 3163</ul> 3164<p>Decodes a string into bytes using Latin-1 (ISO-8859), and encodes those bytes 3165into a string using Base64.</p> 3166<p>The <code>data</code> may be any JavaScript-value that can be coerced into a string.</p> 3167<p><strong>This function is only provided for compatibility with legacy web platform APIs 3168and should never be used in new code, because they use strings to represent 3169binary data and predate the introduction of typed arrays in JavaScript. 3170For code running using Node.js APIs, converting between base64-encoded strings 3171and binary data should be performed using <code>Buffer.from(str, 'base64')</code> and 3172<code>buf.toString('base64')</code>.</strong></p> 3173<h4><code>buffer.INSPECT_MAX_BYTES</code><span><a class="mark" href="#buffer_buffer_inspect_max_bytes" id="buffer_buffer_inspect_max_bytes">#</a></span></h4> 3174<div class="api_metadata"> 3175<span>Added in: v0.5.4</span> 3176</div> 3177<ul> 3178<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> <strong>Default:</strong> <code>50</code></li> 3179</ul> 3180<p>Returns the maximum number of bytes that will be returned when 3181<code>buf.inspect()</code> is called. This can be overridden by user modules. See 3182<a href="util.html#util_util_inspect_object_options"><code>util.inspect()</code></a> for more details on <code>buf.inspect()</code> behavior.</p> 3183<h4><code>buffer.kMaxLength</code><span><a class="mark" href="#buffer_buffer_kmaxlength" id="buffer_buffer_kmaxlength">#</a></span></h4> 3184<div class="api_metadata"> 3185<span>Added in: v3.0.0</span> 3186</div> 3187<ul> 3188<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> The largest size allowed for a single <code>Buffer</code> instance.</li> 3189</ul> 3190<p>An alias for <a href="#buffer_buffer_constants_max_length"><code>buffer.constants.MAX_LENGTH</code></a>.</p> 3191<h4><code>buffer.kStringMaxLength</code><span><a class="mark" href="#buffer_buffer_kstringmaxlength" id="buffer_buffer_kstringmaxlength">#</a></span></h4> 3192<div class="api_metadata"> 3193<span>Added in: v3.0.0</span> 3194</div> 3195<ul> 3196<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> The largest length allowed for a single <code>string</code> instance.</li> 3197</ul> 3198<p>An alias for <a href="#buffer_buffer_constants_max_string_length"><code>buffer.constants.MAX_STRING_LENGTH</code></a>.</p> 3199<h4><code>buffer.transcode(source, fromEnc, toEnc)</code><span><a class="mark" href="#buffer_buffer_transcode_source_fromenc_toenc" id="buffer_buffer_transcode_source_fromenc_toenc">#</a></span></h4> 3200<div class="api_metadata"> 3201<details class="changelog"><summary>History</summary> 3202<table> 3203<tbody><tr><th>Version</th><th>Changes</th></tr> 3204<tr><td>v8.0.0</td> 3205<td><p>The <code>source</code> parameter can now be a <code>Uint8Array</code>.</p></td></tr> 3206<tr><td>v7.1.0</td> 3207<td><p><span>Added in: v7.1.0</span></p></td></tr> 3208</tbody></table> 3209</details> 3210</div> 3211<ul> 3212<li><code>source</code> <a href="buffer.html#buffer_class_buffer" class="type"><Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Uint8Array" class="type"><Uint8Array></a> A <code>Buffer</code> or <code>Uint8Array</code> instance.</li> 3213<li><code>fromEnc</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> The current encoding.</li> 3214<li><code>toEnc</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> To target encoding.</li> 3215<li>Returns: <a href="buffer.html#buffer_class_buffer" class="type"><Buffer></a></li> 3216</ul> 3217<p>Re-encodes the given <code>Buffer</code> or <code>Uint8Array</code> instance from one character 3218encoding to another. Returns a new <code>Buffer</code> instance.</p> 3219<p>Throws if the <code>fromEnc</code> or <code>toEnc</code> specify invalid character encodings or if 3220conversion from <code>fromEnc</code> to <code>toEnc</code> is not permitted.</p> 3221<p>Encodings supported by <code>buffer.transcode()</code> are: <code>'ascii'</code>, <code>'utf8'</code>, 3222<code>'utf16le'</code>, <code>'ucs2'</code>, <code>'latin1'</code>, and <code>'binary'</code>.</p> 3223<p>The transcoding process will use substitution characters if a given byte 3224sequence cannot be adequately represented in the target encoding. For instance:</p> 3225<pre><code class="language-js"><span class="hljs-keyword">const</span> buffer = <span class="hljs-built_in">require</span>(<span class="hljs-string">'buffer'</span>); 3226 3227<span class="hljs-keyword">const</span> newBuf = buffer.<span class="hljs-title function_">transcode</span>(<span class="hljs-title class_">Buffer</span>.<span class="hljs-title function_">from</span>(<span class="hljs-string">'€'</span>), <span class="hljs-string">'utf8'</span>, <span class="hljs-string">'ascii'</span>); 3228<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(newBuf.<span class="hljs-title function_">toString</span>(<span class="hljs-string">'ascii'</span>)); 3229<span class="hljs-comment">// Prints: '?'</span></code></pre> 3230<p>Because the Euro (<code>€</code>) sign is not representable in US-ASCII, it is replaced 3231with <code>?</code> in the transcoded <code>Buffer</code>.</p> 3232<h4>Class: <code>SlowBuffer</code><span><a class="mark" href="#buffer_class_slowbuffer" id="buffer_class_slowbuffer">#</a></span></h4> 3233<div class="api_metadata"> 3234<span>Deprecated since: v6.0.0</span> 3235</div> 3236<p></p><div class="api_stability api_stability_0"><a href="documentation.html#documentation_stability_index">Stability: 0</a> - Deprecated: Use <a href="#buffer_static_method_buffer_allocunsafeslow_size"><code>Buffer.allocUnsafeSlow()</code></a> instead.</div><p></p> 3237<p>See <a href="#buffer_static_method_buffer_allocunsafeslow_size"><code>Buffer.allocUnsafeSlow()</code></a>. This was never a class in the sense that 3238the constructor always returned a <code>Buffer</code> instance, rather than a <code>SlowBuffer</code> 3239instance.</p> 3240<h5><code>new SlowBuffer(size)</code><span><a class="mark" href="#buffer_new_slowbuffer_size" id="buffer_new_slowbuffer_size">#</a></span></h5> 3241<div class="api_metadata"> 3242<span>Deprecated since: v6.0.0</span> 3243</div> 3244<p></p><div class="api_stability api_stability_0"><a href="documentation.html#documentation_stability_index">Stability: 0</a> - Deprecated: Use <a href="#buffer_static_method_buffer_allocunsafeslow_size"><code>Buffer.allocUnsafeSlow()</code></a> instead.</div><p></p> 3245<ul> 3246<li><code>size</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> The desired length of the new <code>SlowBuffer</code>.</li> 3247</ul> 3248<p>See <a href="#buffer_static_method_buffer_allocunsafeslow_size"><code>Buffer.allocUnsafeSlow()</code></a>.</p> 3249<h4>Buffer constants<span><a class="mark" href="#buffer_buffer_constants" id="buffer_buffer_constants">#</a></span></h4> 3250<div class="api_metadata"> 3251<span>Added in: v8.2.0</span> 3252</div> 3253<h5><code>buffer.constants.MAX_LENGTH</code><span><a class="mark" href="#buffer_buffer_constants_max_length" id="buffer_buffer_constants_max_length">#</a></span></h5> 3254<div class="api_metadata"> 3255<details class="changelog"><summary>History</summary> 3256<table> 3257<tbody><tr><th>Version</th><th>Changes</th></tr> 3258<tr><td>v14.0.0</td> 3259<td><p>Value is changed from 2<sup>31</sup> - 1 to 2<sup>32</sup> - 1 on 64-bit architectures.</p></td></tr> 3260<tr><td>v8.2.0</td> 3261<td><p><span>Added in: v8.2.0</span></p></td></tr> 3262</tbody></table> 3263</details> 3264</div> 3265<ul> 3266<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> The largest size allowed for a single <code>Buffer</code> instance.</li> 3267</ul> 3268<p>On 32-bit architectures, this value currently is 2<sup>30</sup> - 1 (~1GB).</p> 3269<p>On 64-bit architectures, this value currently is 2<sup>32</sup> - 1 (~4GB).</p> 3270<p>It reflects <a href="https://v8.github.io/api/head/classv8_1_1TypedArray.html#a54a48f4373da0850663c4393d843b9b0"><code>v8::TypedArray::kMaxLength</code></a> under the hood.</p> 3271<p>This value is also available as <a href="#buffer_buffer_kmaxlength"><code>buffer.kMaxLength</code></a>.</p> 3272<h5><code>buffer.constants.MAX_STRING_LENGTH</code><span><a class="mark" href="#buffer_buffer_constants_max_string_length" id="buffer_buffer_constants_max_string_length">#</a></span></h5> 3273<div class="api_metadata"> 3274<span>Added in: v8.2.0</span> 3275</div> 3276<ul> 3277<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> The largest length allowed for a single <code>string</code> instance.</li> 3278</ul> 3279<p>Represents the largest <code>length</code> that a <code>string</code> primitive can have, counted 3280in UTF-16 code units.</p> 3281<p>This value may depend on the JS engine that is being used.</p> 3282</section><section><h3><code>Buffer.from()</code>, <code>Buffer.alloc()</code>, and <code>Buffer.allocUnsafe()</code><span><a class="mark" href="#buffer_buffer_from_buffer_alloc_and_buffer_allocunsafe" id="buffer_buffer_from_buffer_alloc_and_buffer_allocunsafe">#</a></span></h3> 3283<p>In versions of Node.js prior to 6.0.0, <code>Buffer</code> instances were created using the 3284<code>Buffer</code> constructor function, which allocates the returned <code>Buffer</code> 3285differently based on what arguments are provided:</p> 3286<ul> 3287<li>Passing a number as the first argument to <code>Buffer()</code> (e.g. <code>new Buffer(10)</code>) 3288allocates a new <code>Buffer</code> object of the specified size. Prior to Node.js 8.0.0, 3289the memory allocated for such <code>Buffer</code> instances is <em>not</em> initialized and 3290<em>can contain sensitive data</em>. Such <code>Buffer</code> instances <em>must</em> be subsequently 3291initialized by using either <a href="#buffer_buf_fill_value_offset_end_encoding"><code>buf.fill(0)</code></a> or by writing to the 3292entire <code>Buffer</code> before reading data from the <code>Buffer</code>. 3293While this behavior is <em>intentional</em> to improve performance, 3294development experience has demonstrated that a more explicit distinction is 3295required between creating a fast-but-uninitialized <code>Buffer</code> versus creating a 3296slower-but-safer <code>Buffer</code>. Since Node.js 8.0.0, <code>Buffer(num)</code> and <code>new Buffer(num)</code> return a <code>Buffer</code> with initialized memory.</li> 3297<li>Passing a string, array, or <code>Buffer</code> as the first argument copies the 3298passed object's data into the <code>Buffer</code>.</li> 3299<li>Passing an <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/ArrayBuffer"><code>ArrayBuffer</code></a> or a <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/SharedArrayBuffer"><code>SharedArrayBuffer</code></a> returns a <code>Buffer</code> 3300that shares allocated memory with the given array buffer.</li> 3301</ul> 3302<p>Because the behavior of <code>new Buffer()</code> is different depending on the type of the 3303first argument, security and reliability issues can be inadvertently introduced 3304into applications when argument validation or <code>Buffer</code> initialization is not 3305performed.</p> 3306<p>For example, if an attacker can cause an application to receive a number where 3307a string is expected, the application may call <code>new Buffer(100)</code> 3308instead of <code>new Buffer("100")</code>, leading it to allocate a 100 byte buffer instead 3309of allocating a 3 byte buffer with content <code>"100"</code>. This is commonly possible 3310using JSON API calls. Since JSON distinguishes between numeric and string types, 3311it allows injection of numbers where a naively written application that does not 3312validate its input sufficiently might expect to always receive a string. 3313Before Node.js 8.0.0, the 100 byte buffer might contain 3314arbitrary pre-existing in-memory data, so may be used to expose in-memory 3315secrets to a remote attacker. Since Node.js 8.0.0, exposure of memory cannot 3316occur because the data is zero-filled. However, other attacks are still 3317possible, such as causing very large buffers to be allocated by the server, 3318leading to performance degradation or crashing on memory exhaustion.</p> 3319<p>To make the creation of <code>Buffer</code> instances more reliable and less error-prone, 3320the various forms of the <code>new Buffer()</code> constructor have been <strong>deprecated</strong> 3321and replaced by separate <code>Buffer.from()</code>, <a href="#buffer_static_method_buffer_alloc_size_fill_encoding"><code>Buffer.alloc()</code></a>, and 3322<a href="#buffer_static_method_buffer_allocunsafe_size"><code>Buffer.allocUnsafe()</code></a> methods.</p> 3323<p><em>Developers should migrate all existing uses of the <code>new Buffer()</code> constructors 3324to one of these new APIs.</em></p> 3325<ul> 3326<li><a href="#buffer_static_method_buffer_from_array"><code>Buffer.from(array)</code></a> returns a new <code>Buffer</code> that <em>contains a copy</em> of the 3327provided octets.</li> 3328<li><a href="#buffer_static_method_buffer_from_arraybuffer_byteoffset_length"><code>Buffer.from(arrayBuffer[, byteOffset[, length]])</code></a> 3329returns a new <code>Buffer</code> that <em>shares the same allocated memory</em> as the given 3330<a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/ArrayBuffer"><code>ArrayBuffer</code></a>.</li> 3331<li><a href="#buffer_static_method_buffer_from_buffer"><code>Buffer.from(buffer)</code></a> returns a new <code>Buffer</code> that <em>contains a copy</em> of the 3332contents of the given <code>Buffer</code>.</li> 3333<li><a href="#buffer_static_method_buffer_from_string_encoding"><code>Buffer.from(string[, encoding])</code></a> returns a new 3334<code>Buffer</code> that <em>contains a copy</em> of the provided string.</li> 3335<li><a href="#buffer_static_method_buffer_alloc_size_fill_encoding"><code>Buffer.alloc(size[, fill[, encoding]])</code></a> returns a new 3336initialized <code>Buffer</code> of the specified size. This method is slower than 3337<a href="#buffer_static_method_buffer_allocunsafe_size"><code>Buffer.allocUnsafe(size)</code></a> but guarantees that newly 3338created <code>Buffer</code> instances never contain old data that is potentially 3339sensitive. A <code>TypeError</code> will be thrown if <code>size</code> is not a number.</li> 3340<li><a href="#buffer_static_method_buffer_allocunsafe_size"><code>Buffer.allocUnsafe(size)</code></a> and 3341<a href="#buffer_static_method_buffer_allocunsafeslow_size"><code>Buffer.allocUnsafeSlow(size)</code></a> each return a 3342new uninitialized <code>Buffer</code> of the specified <code>size</code>. Because the <code>Buffer</code> is 3343uninitialized, the allocated segment of memory might contain old data that is 3344potentially sensitive.</li> 3345</ul> 3346<p><code>Buffer</code> instances returned by <a href="#buffer_static_method_buffer_allocunsafe_size"><code>Buffer.allocUnsafe()</code></a> and 3347<a href="#buffer_static_method_buffer_from_array"><code>Buffer.from(array)</code></a> <em>may</em> be allocated off a shared internal memory pool 3348if <code>size</code> is less than or equal to half <a href="#buffer_class_property_buffer_poolsize"><code>Buffer.poolSize</code></a>. Instances 3349returned by <a href="#buffer_static_method_buffer_allocunsafeslow_size"><code>Buffer.allocUnsafeSlow()</code></a> <em>never</em> use the shared internal 3350memory pool.</p> 3351<h4>The <code>--zero-fill-buffers</code> command-line option<span><a class="mark" href="#buffer_the_zero_fill_buffers_command_line_option" id="buffer_the_zero_fill_buffers_command_line_option">#</a></span></h4> 3352<div class="api_metadata"> 3353<span>Added in: v5.10.0</span> 3354</div> 3355<p>Node.js can be started using the <code>--zero-fill-buffers</code> command-line option to 3356cause all newly-allocated <code>Buffer</code> instances to be zero-filled upon creation by 3357default. Without the option, buffers created with <a href="#buffer_static_method_buffer_allocunsafe_size"><code>Buffer.allocUnsafe()</code></a>, 3358<a href="#buffer_static_method_buffer_allocunsafeslow_size"><code>Buffer.allocUnsafeSlow()</code></a>, and <code>new SlowBuffer(size)</code> are not zero-filled. 3359Use of this flag can have a measurable negative impact on performance. Use the 3360<code>--zero-fill-buffers</code> option only when necessary to enforce that newly allocated 3361<code>Buffer</code> instances cannot contain old data that is potentially sensitive.</p> 3362<pre><code class="language-console"><span class="hljs-meta">$ </span><span class="language-bash">node --zero-fill-buffers</span> 3363<span class="hljs-meta">> </span><span class="language-bash">Buffer.allocUnsafe(5);</span> 3364<Buffer 00 00 00 00 00></code></pre> 3365<h4>What makes <code>Buffer.allocUnsafe()</code> and <code>Buffer.allocUnsafeSlow()</code> "unsafe"?<span><a class="mark" href="#buffer_what_makes_buffer_allocunsafe_and_buffer_allocunsafeslow_unsafe" id="buffer_what_makes_buffer_allocunsafe_and_buffer_allocunsafeslow_unsafe">#</a></span></h4> 3366<p>When calling <a href="#buffer_static_method_buffer_allocunsafe_size"><code>Buffer.allocUnsafe()</code></a> and <a href="#buffer_static_method_buffer_allocunsafeslow_size"><code>Buffer.allocUnsafeSlow()</code></a>, the 3367segment of allocated memory is <em>uninitialized</em> (it is not zeroed-out). While 3368this design makes the allocation of memory quite fast, the allocated segment of 3369memory might contain old data that is potentially sensitive. Using a <code>Buffer</code> 3370created by <a href="#buffer_static_method_buffer_allocunsafe_size"><code>Buffer.allocUnsafe()</code></a> without <em>completely</em> overwriting the 3371memory can allow this old data to be leaked when the <code>Buffer</code> memory is read.</p> 3372<p>While there are clear performance advantages to using 3373<a href="#buffer_static_method_buffer_allocunsafe_size"><code>Buffer.allocUnsafe()</code></a>, extra care <em>must</em> be taken in order to avoid 3374introducing security vulnerabilities into an application.</p></section> 3375 <!-- API END --> 3376 </div> 3377 </div> 3378 </div> 3379 <script> 3380 'use strict'; 3381 { 3382 const kCustomPreference = 'customDarkTheme'; 3383 const userSettings = sessionStorage.getItem(kCustomPreference); 3384 const themeToggleButton = document.getElementById('theme-toggle-btn'); 3385 if (userSettings === null && window.matchMedia) { 3386 const mq = window.matchMedia('(prefers-color-scheme: dark)'); 3387 if ('onchange' in mq) { 3388 function mqChangeListener(e) { 3389 document.body.classList.toggle('dark-mode', e.matches); 3390 } 3391 mq.addEventListener('change', mqChangeListener); 3392 if (themeToggleButton) { 3393 themeToggleButton.addEventListener('click', function() { 3394 mq.removeEventListener('change', mqChangeListener); 3395 }, { once: true }); 3396 } 3397 } 3398 if (mq.matches) { 3399 document.body.classList.add('dark-mode'); 3400 } 3401 } else if (userSettings === 'true') { 3402 document.body.classList.add('dark-mode'); 3403 } 3404 if (themeToggleButton) { 3405 themeToggleButton.hidden = false; 3406 themeToggleButton.addEventListener('click', function() { 3407 sessionStorage.setItem( 3408 kCustomPreference, 3409 document.body.classList.toggle('dark-mode') 3410 ); 3411 }); 3412 } 3413 } 3414 </script> 3415</body> 3416</html> 3417