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data-id="intl" class="interior"> 90 <header> 91 <div class="header-container"> 92 <h1>Node.js v14.21.2 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 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href="#intl_internationalization_support">Internationalization support</a> 141<ul> 142<li><a href="#intl_options_for_building_node_js">Options for building Node.js</a> 143<ul> 144<li><a href="#intl_disable_all_internationalization_features_none">Disable all internationalization features (<code>none</code>)</a></li> 145<li><a href="#intl_build_with_a_pre_installed_icu_system_icu">Build with a pre-installed ICU (<code>system-icu</code>)</a></li> 146<li><a href="#intl_embed_a_limited_set_of_icu_data_small_icu">Embed a limited set of ICU data (<code>small-icu</code>)</a> 147<ul> 148<li><a href="#intl_providing_icu_data_at_runtime">Providing ICU data at runtime</a></li> 149</ul> 150</li> 151<li><a href="#intl_embed_the_entire_icu_full_icu">Embed the entire ICU (<code>full-icu</code>)</a></li> 152</ul> 153</li> 154<li><a href="#intl_detecting_internationalization_support">Detecting internationalization support</a></li> 155</ul> 156</li> 157</ul></details> 158 159 <div id="apicontent"> 160 <h2>Internationalization support<span><a class="mark" href="#intl_internationalization_support" id="intl_internationalization_support">#</a></span></h2> 161 162 163<p>Node.js has many features that make it easier to write internationalized 164programs. Some of them are:</p> 165<ul> 166<li>Locale-sensitive or Unicode-aware functions in the <a href="https://tc39.github.io/ecma262/">ECMAScript Language 167Specification</a>: 168<ul> 169<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/normalize"><code>String.prototype.normalize()</code></a></li> 170<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/toLowerCase"><code>String.prototype.toLowerCase()</code></a></li> 171<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/toUpperCase"><code>String.prototype.toUpperCase()</code></a></li> 172</ul> 173</li> 174<li>All functionality described in the <a href="https://tc39.github.io/ecma402/">ECMAScript Internationalization API 175Specification</a> (aka ECMA-402): 176<ul> 177<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl"><code>Intl</code></a> object</li> 178<li>Locale-sensitive methods like <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/localeCompare"><code>String.prototype.localeCompare()</code></a> and 179<a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/toLocaleString"><code>Date.prototype.toLocaleString()</code></a></li> 180</ul> 181</li> 182<li>The <a href="url.html#url_the_whatwg_url_api">WHATWG URL parser</a>'s <a href="https://en.wikipedia.org/wiki/Internationalized_domain_name">internationalized domain names</a> (IDNs) support</li> 183<li><a href="buffer.html#buffer_buffer_transcode_source_fromenc_toenc"><code>require('buffer').transcode()</code></a></li> 184<li>More accurate <a href="repl.html#repl_repl">REPL</a> line editing</li> 185<li><a href="util.html#util_class_util_textdecoder"><code>require('util').TextDecoder</code></a></li> 186<li><a href="https://github.com/tc39/proposal-regexp-unicode-property-escapes"><code>RegExp</code> Unicode Property Escapes</a></li> 187</ul> 188<p>Node.js and the underlying V8 engine use 189<a href="http://site.icu-project.org/">International Components for Unicode (ICU)</a> to implement these features 190in native C/C++ code. The full ICU data set is provided by Node.js by default. 191However, due to the size of the ICU data file, several 192options are provided for customizing the ICU data set either when 193building or running Node.js.</p> 194<section><h3>Options for building Node.js<span><a class="mark" href="#intl_options_for_building_node_js" id="intl_options_for_building_node_js">#</a></span></h3> 195<p>To control how ICU is used in Node.js, four <code>configure</code> options are available 196during compilation. Additional details on how to compile Node.js are documented 197in <a href="https://github.com/nodejs/node/blob/HEAD/BUILDING.md">BUILDING.md</a>.</p> 198<ul> 199<li><code>--with-intl=none</code>/<code>--without-intl</code></li> 200<li><code>--with-intl=system-icu</code></li> 201<li><code>--with-intl=small-icu</code></li> 202<li><code>--with-intl=full-icu</code> (default)</li> 203</ul> 204<p>An overview of available Node.js and JavaScript features for each <code>configure</code> 205option:</p> 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302<table><thead><tr><th>Feature</th><th><code>none</code></th><th><code>system-icu</code></th><th><code>small-icu</code></th><th><code>full-icu</code></th></tr></thead><tbody><tr><td><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/normalize"><code>String.prototype.normalize()</code></a></td><td>none (function is no-op)</td><td>full</td><td>full</td><td>full</td></tr><tr><td><code>String.prototype.to*Case()</code></td><td>full</td><td>full</td><td>full</td><td>full</td></tr><tr><td><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl"><code>Intl</code></a></td><td>none (object does not exist)</td><td>partial/full (depends on OS)</td><td>partial (English-only)</td><td>full</td></tr><tr><td><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/localeCompare"><code>String.prototype.localeCompare()</code></a></td><td>partial (not locale-aware)</td><td>full</td><td>full</td><td>full</td></tr><tr><td><code>String.prototype.toLocale*Case()</code></td><td>partial (not locale-aware)</td><td>full</td><td>full</td><td>full</td></tr><tr><td><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/toLocaleString"><code>Number.prototype.toLocaleString()</code></a></td><td>partial (not locale-aware)</td><td>partial/full (depends on OS)</td><td>partial (English-only)</td><td>full</td></tr><tr><td><code>Date.prototype.toLocale*String()</code></td><td>partial (not locale-aware)</td><td>partial/full (depends on OS)</td><td>partial (English-only)</td><td>full</td></tr><tr><td><a href="url.html#url_the_whatwg_url_api">WHATWG URL Parser</a></td><td>partial (no IDN support)</td><td>full</td><td>full</td><td>full</td></tr><tr><td><a href="buffer.html#buffer_buffer_transcode_source_fromenc_toenc"><code>require('buffer').transcode()</code></a></td><td>none (function does not exist)</td><td>full</td><td>full</td><td>full</td></tr><tr><td><a href="repl.html#repl_repl">REPL</a></td><td>partial (inaccurate line editing)</td><td>full</td><td>full</td><td>full</td></tr><tr><td><a href="util.html#util_class_util_textdecoder"><code>require('util').TextDecoder</code></a></td><td>partial (basic encodings support)</td><td>partial/full (depends on OS)</td><td>partial (Unicode-only)</td><td>full</td></tr><tr><td><a href="https://github.com/tc39/proposal-regexp-unicode-property-escapes"><code>RegExp</code> Unicode Property Escapes</a></td><td>none (invalid <code>RegExp</code> error)</td><td>full</td><td>full</td><td>full</td></tr></tbody></table> 303<p>The "(not locale-aware)" designation denotes that the function carries out its 304operation just like the non-<code>Locale</code> version of the function, if one 305exists. For example, under <code>none</code> mode, <code>Date.prototype.toLocaleString()</code>'s 306operation is identical to that of <code>Date.prototype.toString()</code>.</p> 307<h4>Disable all internationalization features (<code>none</code>)<span><a class="mark" href="#intl_disable_all_internationalization_features_none" id="intl_disable_all_internationalization_features_none">#</a></span></h4> 308<p>If this option is chosen, ICU is disabled and most internationalization 309features mentioned above will be <strong>unavailable</strong> in the resulting <code>node</code> binary.</p> 310<h4>Build with a pre-installed ICU (<code>system-icu</code>)<span><a class="mark" href="#intl_build_with_a_pre_installed_icu_system_icu" id="intl_build_with_a_pre_installed_icu_system_icu">#</a></span></h4> 311<p>Node.js can link against an ICU build already installed on the system. In fact, 312most Linux distributions already come with ICU installed, and this option would 313make it possible to reuse the same set of data used by other components in the 314OS.</p> 315<p>Functionalities that only require the ICU library itself, such as 316<a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/normalize"><code>String.prototype.normalize()</code></a> and the <a href="url.html#url_the_whatwg_url_api">WHATWG URL parser</a>, are fully 317supported under <code>system-icu</code>. Features that require ICU locale data in 318addition, such as <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DateTimeFormat"><code>Intl.DateTimeFormat</code></a> <em>may</em> be fully or partially 319supported, depending on the completeness of the ICU data installed on the 320system.</p> 321<h4>Embed a limited set of ICU data (<code>small-icu</code>)<span><a class="mark" href="#intl_embed_a_limited_set_of_icu_data_small_icu" id="intl_embed_a_limited_set_of_icu_data_small_icu">#</a></span></h4> 322<p>This option makes the resulting binary link against the ICU library statically, 323and includes a subset of ICU data (typically only the English locale) within 324the <code>node</code> executable.</p> 325<p>Functionalities that only require the ICU library itself, such as 326<a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/normalize"><code>String.prototype.normalize()</code></a> and the <a href="url.html#url_the_whatwg_url_api">WHATWG URL parser</a>, are fully 327supported under <code>small-icu</code>. Features that require ICU locale data in addition, 328such as <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DateTimeFormat"><code>Intl.DateTimeFormat</code></a>, generally only work with the English locale:</p> 329<pre><code class="language-js"><span class="hljs-keyword">const</span> january = <span class="hljs-keyword">new</span> <span class="hljs-title class_">Date</span>(<span class="hljs-number">9e8</span>); 330<span class="hljs-keyword">const</span> english = <span class="hljs-keyword">new</span> <span class="hljs-title class_">Intl</span>.<span class="hljs-title class_">DateTimeFormat</span>(<span class="hljs-string">'en'</span>, { <span class="hljs-attr">month</span>: <span class="hljs-string">'long'</span> }); 331<span class="hljs-keyword">const</span> spanish = <span class="hljs-keyword">new</span> <span class="hljs-title class_">Intl</span>.<span class="hljs-title class_">DateTimeFormat</span>(<span class="hljs-string">'es'</span>, { <span class="hljs-attr">month</span>: <span class="hljs-string">'long'</span> }); 332 333<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(english.<span class="hljs-title function_">format</span>(january)); 334<span class="hljs-comment">// Prints "January"</span> 335<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(spanish.<span class="hljs-title function_">format</span>(january)); 336<span class="hljs-comment">// Prints "M01" on small-icu</span> 337<span class="hljs-comment">// Should print "enero"</span></code></pre> 338<p>This mode provides a balance between features and binary size.</p> 339<h5>Providing ICU data at runtime<span><a class="mark" href="#intl_providing_icu_data_at_runtime" id="intl_providing_icu_data_at_runtime">#</a></span></h5> 340<p>If the <code>small-icu</code> option is used, one can still provide additional locale data 341at runtime so that the JS methods would work for all ICU locales. Assuming the 342data file is stored at <code>/some/directory</code>, it can be made available to ICU 343through either:</p> 344<ul> 345<li> 346<p>The <a href="cli.html#cli_node_icu_data_file"><code>NODE_ICU_DATA</code></a> environment variable:</p> 347<pre><code class="language-bash">env NODE_ICU_DATA=/some/directory node</code></pre> 348</li> 349<li> 350<p>The <a href="cli.html#cli_icu_data_dir_file"><code>--icu-data-dir</code></a> CLI parameter:</p> 351<pre><code class="language-bash">node --icu-data-dir=/some/directory</code></pre> 352</li> 353</ul> 354<p>(If both are specified, the <code>--icu-data-dir</code> CLI parameter takes precedence.)</p> 355<p>ICU is able to automatically find and load a variety of data formats, but the 356data must be appropriate for the ICU version, and the file correctly named. 357The most common name for the data file is <code>icudt6X[bl].dat</code>, where <code>6X</code> denotes 358the intended ICU version, and <code>b</code> or <code>l</code> indicates the system's endianness. 359Check <a href="http://userguide.icu-project.org/icudata">"ICU Data"</a> article in the ICU User Guide for other supported formats 360and more details on ICU data in general.</p> 361<p>The <a href="https://www.npmjs.com/package/full-icu">full-icu</a> npm module can greatly simplify ICU data installation by 362detecting the ICU version of the running <code>node</code> executable and downloading the 363appropriate data file. After installing the module through <code>npm i full-icu</code>, 364the data file will be available at <code>./node_modules/full-icu</code>. This path can be 365then passed either to <code>NODE_ICU_DATA</code> or <code>--icu-data-dir</code> as shown above to 366enable full <code>Intl</code> support.</p> 367<h4>Embed the entire ICU (<code>full-icu</code>)<span><a class="mark" href="#intl_embed_the_entire_icu_full_icu" id="intl_embed_the_entire_icu_full_icu">#</a></span></h4> 368<p>This option makes the resulting binary link against ICU statically and include 369a full set of ICU data. A binary created this way has no further external 370dependencies and supports all locales, but might be rather large. This is 371the default behavior if no <code>--with-intl</code> flag is passed. The official binaries 372are also built in this mode.</p> 373</section><section><h3>Detecting internationalization support<span><a class="mark" href="#intl_detecting_internationalization_support" id="intl_detecting_internationalization_support">#</a></span></h3> 374<p>To verify that ICU is enabled at all (<code>system-icu</code>, <code>small-icu</code>, or 375<code>full-icu</code>), simply checking the existence of <code>Intl</code> should suffice:</p> 376<pre><code class="language-js"><span class="hljs-keyword">const</span> hasICU = <span class="hljs-keyword">typeof</span> <span class="hljs-title class_">Intl</span> === <span class="hljs-string">'object'</span>;</code></pre> 377<p>Alternatively, checking for <code>process.versions.icu</code>, a property defined only 378when ICU is enabled, works too:</p> 379<pre><code class="language-js"><span class="hljs-keyword">const</span> hasICU = <span class="hljs-keyword">typeof</span> process.<span class="hljs-property">versions</span>.<span class="hljs-property">icu</span> === <span class="hljs-string">'string'</span>;</code></pre> 380<p>To check for support for a non-English locale (i.e. <code>full-icu</code> or 381<code>system-icu</code>), <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DateTimeFormat"><code>Intl.DateTimeFormat</code></a> can be a good distinguishing factor:</p> 382<pre><code class="language-js"><span class="hljs-keyword">const</span> hasFullICU = (<span class="hljs-function">() =></span> { 383 <span class="hljs-keyword">try</span> { 384 <span class="hljs-keyword">const</span> january = <span class="hljs-keyword">new</span> <span class="hljs-title class_">Date</span>(<span class="hljs-number">9e8</span>); 385 <span class="hljs-keyword">const</span> spanish = <span class="hljs-keyword">new</span> <span class="hljs-title class_">Intl</span>.<span class="hljs-title class_">DateTimeFormat</span>(<span class="hljs-string">'es'</span>, { <span class="hljs-attr">month</span>: <span class="hljs-string">'long'</span> }); 386 <span class="hljs-keyword">return</span> spanish.<span class="hljs-title function_">format</span>(january) === <span class="hljs-string">'enero'</span>; 387 } <span class="hljs-keyword">catch</span> (err) { 388 <span class="hljs-keyword">return</span> <span class="hljs-literal">false</span>; 389 } 390})();</code></pre> 391<p>For more verbose tests for <code>Intl</code> support, the following resources may be found 392to be helpful:</p> 393<ul> 394<li><a href="https://github.com/srl295/btest402">btest402</a>: Generally used to check whether Node.js with <code>Intl</code> support is 395built correctly.</li> 396<li><a href="https://github.com/tc39/test262/tree/HEAD/test/intl402">Test262</a>: ECMAScript's official conformance test suite includes a section 397dedicated to ECMA-402.</li> 398</ul></section> 399 <!-- API END --> 400 </div> 401 </div> 402 </div> 403 <script> 404 'use strict'; 405 { 406 const kCustomPreference = 'customDarkTheme'; 407 const userSettings = sessionStorage.getItem(kCustomPreference); 408 const themeToggleButton = document.getElementById('theme-toggle-btn'); 409 if (userSettings === null && window.matchMedia) { 410 const mq = window.matchMedia('(prefers-color-scheme: dark)'); 411 if ('onchange' in mq) { 412 function mqChangeListener(e) { 413 document.body.classList.toggle('dark-mode', e.matches); 414 } 415 mq.addEventListener('change', mqChangeListener); 416 if (themeToggleButton) { 417 themeToggleButton.addEventListener('click', function() { 418 mq.removeEventListener('change', mqChangeListener); 419 }, { once: true }); 420 } 421 } 422 if (mq.matches) { 423 document.body.classList.add('dark-mode'); 424 } 425 } else if (userSettings === 'true') { 426 document.body.classList.add('dark-mode'); 427 } 428 if (themeToggleButton) { 429 themeToggleButton.hidden = false; 430 themeToggleButton.addEventListener('click', function() { 431 sessionStorage.setItem( 432 kCustomPreference, 433 document.body.classList.toggle('dark-mode') 434 ); 435 }); 436 } 437 } 438 </script> 439</body> 440</html> 441