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data-id="intl" class="interior"> 90 <header> 91 <div class="header-container"> 92 <h1>Node.js v14.20.1 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 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href="#intl_options_for_building_node_js">Options for building Node.js</a> 142<ul> 143<li><a href="#intl_disable_all_internationalization_features_none">Disable all internationalization features (<code>none</code>)</a></li> 144<li><a href="#intl_build_with_a_pre_installed_icu_system_icu">Build with a pre-installed ICU (<code>system-icu</code>)</a></li> 145<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> 146<ul> 147<li><a href="#intl_providing_icu_data_at_runtime">Providing ICU data at runtime</a></li> 148</ul> 149</li> 150<li><a href="#intl_embed_the_entire_icu_full_icu">Embed the entire ICU (<code>full-icu</code>)</a></li> 151</ul> 152</li> 153<li><a href="#intl_detecting_internationalization_support">Detecting internationalization support</a></li> 154</ul> 155</li> 156</ul></details> 157 158 <div id="apicontent"> 159 <h2>Internationalization support<span><a class="mark" href="#intl_internationalization_support" id="intl_internationalization_support">#</a></span></h2> 160 161 162<p>Node.js has many features that make it easier to write internationalized 163programs. Some of them are:</p> 164<ul> 165<li>Locale-sensitive or Unicode-aware functions in the <a href="https://tc39.github.io/ecma262/">ECMAScript Language 166Specification</a>: 167<ul> 168<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/normalize"><code>String.prototype.normalize()</code></a></li> 169<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/toLowerCase"><code>String.prototype.toLowerCase()</code></a></li> 170<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/toUpperCase"><code>String.prototype.toUpperCase()</code></a></li> 171</ul> 172</li> 173<li>All functionality described in the <a href="https://tc39.github.io/ecma402/">ECMAScript Internationalization API 174Specification</a> (aka ECMA-402): 175<ul> 176<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl"><code>Intl</code></a> object</li> 177<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 178<a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/toLocaleString"><code>Date.prototype.toLocaleString()</code></a></li> 179</ul> 180</li> 181<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> 182<li><a href="buffer.html#buffer_buffer_transcode_source_fromenc_toenc"><code>require('buffer').transcode()</code></a></li> 183<li>More accurate <a href="repl.html#repl_repl">REPL</a> line editing</li> 184<li><a href="util.html#util_class_util_textdecoder"><code>require('util').TextDecoder</code></a></li> 185<li><a href="https://github.com/tc39/proposal-regexp-unicode-property-escapes"><code>RegExp</code> Unicode Property Escapes</a></li> 186</ul> 187<p>Node.js and the underlying V8 engine use 188<a href="http://site.icu-project.org/">International Components for Unicode (ICU)</a> to implement these features 189in native C/C++ code. The full ICU data set is provided by Node.js by default. 190However, due to the size of the ICU data file, several 191options are provided for customizing the ICU data set either when 192building or running Node.js.</p> 193<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> 194<p>To control how ICU is used in Node.js, four <code>configure</code> options are available 195during compilation. Additional details on how to compile Node.js are documented 196in <a href="https://github.com/nodejs/node/blob/HEAD/BUILDING.md">BUILDING.md</a>.</p> 197<ul> 198<li><code>--with-intl=none</code>/<code>--without-intl</code></li> 199<li><code>--with-intl=system-icu</code></li> 200<li><code>--with-intl=small-icu</code></li> 201<li><code>--with-intl=full-icu</code> (default)</li> 202</ul> 203<p>An overview of available Node.js and JavaScript features for each <code>configure</code> 204option:</p> 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301<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> 302<p>The "(not locale-aware)" designation denotes that the function carries out its 303operation just like the non-<code>Locale</code> version of the function, if one 304exists. For example, under <code>none</code> mode, <code>Date.prototype.toLocaleString()</code>'s 305operation is identical to that of <code>Date.prototype.toString()</code>.</p> 306<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> 307<p>If this option is chosen, ICU is disabled and most internationalization 308features mentioned above will be <strong>unavailable</strong> in the resulting <code>node</code> binary.</p> 309<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> 310<p>Node.js can link against an ICU build already installed on the system. In fact, 311most Linux distributions already come with ICU installed, and this option would 312make it possible to reuse the same set of data used by other components in the 313OS.</p> 314<p>Functionalities that only require the ICU library itself, such as 315<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 316supported under <code>system-icu</code>. Features that require ICU locale data in 317addition, 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 318supported, depending on the completeness of the ICU data installed on the 319system.</p> 320<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> 321<p>This option makes the resulting binary link against the ICU library statically, 322and includes a subset of ICU data (typically only the English locale) within 323the <code>node</code> executable.</p> 324<p>Functionalities that only require the ICU library itself, such as 325<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 326supported under <code>small-icu</code>. Features that require ICU locale data in addition, 327such 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> 328<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>); 329<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> }); 330<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> }); 331 332<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(english.<span class="hljs-title function_">format</span>(january)); 333<span class="hljs-comment">// Prints "January"</span> 334<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(spanish.<span class="hljs-title function_">format</span>(january)); 335<span class="hljs-comment">// Prints "M01" on small-icu</span> 336<span class="hljs-comment">// Should print "enero"</span></code></pre> 337<p>This mode provides a balance between features and binary size.</p> 338<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> 339<p>If the <code>small-icu</code> option is used, one can still provide additional locale data 340at runtime so that the JS methods would work for all ICU locales. Assuming the 341data file is stored at <code>/some/directory</code>, it can be made available to ICU 342through either:</p> 343<ul> 344<li> 345<p>The <a href="cli.html#cli_node_icu_data_file"><code>NODE_ICU_DATA</code></a> environment variable:</p> 346<pre><code class="language-bash">env NODE_ICU_DATA=/some/directory node</code></pre> 347</li> 348<li> 349<p>The <a href="cli.html#cli_icu_data_dir_file"><code>--icu-data-dir</code></a> CLI parameter:</p> 350<pre><code class="language-bash">node --icu-data-dir=/some/directory</code></pre> 351</li> 352</ul> 353<p>(If both are specified, the <code>--icu-data-dir</code> CLI parameter takes precedence.)</p> 354<p>ICU is able to automatically find and load a variety of data formats, but the 355data must be appropriate for the ICU version, and the file correctly named. 356The most common name for the data file is <code>icudt6X[bl].dat</code>, where <code>6X</code> denotes 357the intended ICU version, and <code>b</code> or <code>l</code> indicates the system's endianness. 358Check <a href="http://userguide.icu-project.org/icudata">"ICU Data"</a> article in the ICU User Guide for other supported formats 359and more details on ICU data in general.</p> 360<p>The <a href="https://www.npmjs.com/package/full-icu">full-icu</a> npm module can greatly simplify ICU data installation by 361detecting the ICU version of the running <code>node</code> executable and downloading the 362appropriate data file. After installing the module through <code>npm i full-icu</code>, 363the data file will be available at <code>./node_modules/full-icu</code>. This path can be 364then passed either to <code>NODE_ICU_DATA</code> or <code>--icu-data-dir</code> as shown above to 365enable full <code>Intl</code> support.</p> 366<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> 367<p>This option makes the resulting binary link against ICU statically and include 368a full set of ICU data. A binary created this way has no further external 369dependencies and supports all locales, but might be rather large. This is 370the default behavior if no <code>--with-intl</code> flag is passed. The official binaries 371are also built in this mode.</p> 372</section><section><h3>Detecting internationalization support<span><a class="mark" href="#intl_detecting_internationalization_support" id="intl_detecting_internationalization_support">#</a></span></h3> 373<p>To verify that ICU is enabled at all (<code>system-icu</code>, <code>small-icu</code>, or 374<code>full-icu</code>), simply checking the existence of <code>Intl</code> should suffice:</p> 375<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> 376<p>Alternatively, checking for <code>process.versions.icu</code>, a property defined only 377when ICU is enabled, works too:</p> 378<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> 379<p>To check for support for a non-English locale (i.e. <code>full-icu</code> or 380<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> 381<pre><code class="language-js"><span class="hljs-keyword">const</span> hasFullICU = (<span class="hljs-function">() =></span> { 382 <span class="hljs-keyword">try</span> { 383 <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>); 384 <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> }); 385 <span class="hljs-keyword">return</span> spanish.<span class="hljs-title function_">format</span>(january) === <span class="hljs-string">'enero'</span>; 386 } <span class="hljs-keyword">catch</span> (err) { 387 <span class="hljs-keyword">return</span> <span class="hljs-literal">false</span>; 388 } 389})();</code></pre> 390<p>For more verbose tests for <code>Intl</code> support, the following resources may be found 391to be helpful:</p> 392<ul> 393<li><a href="https://github.com/srl295/btest402">btest402</a>: Generally used to check whether Node.js with <code>Intl</code> support is 394built correctly.</li> 395<li><a href="https://github.com/tc39/test262/tree/HEAD/test/intl402">Test262</a>: ECMAScript's official conformance test suite includes a section 396dedicated to ECMA-402.</li> 397</ul></section> 398 <!-- API END --> 399 </div> 400 </div> 401 </div> 402 <script> 403 'use strict'; 404 { 405 const kCustomPreference = 'customDarkTheme'; 406 const userSettings = sessionStorage.getItem(kCustomPreference); 407 const themeToggleButton = document.getElementById('theme-toggle-btn'); 408 if (userSettings === null && window.matchMedia) { 409 const mq = window.matchMedia('(prefers-color-scheme: dark)'); 410 if ('onchange' in mq) { 411 function mqChangeListener(e) { 412 document.body.classList.toggle('dark-mode', e.matches); 413 } 414 mq.addEventListener('change', mqChangeListener); 415 if (themeToggleButton) { 416 themeToggleButton.addEventListener('click', function() { 417 mq.removeEventListener('change', mqChangeListener); 418 }, { once: true }); 419 } 420 } 421 if (mq.matches) { 422 document.body.classList.add('dark-mode'); 423 } 424 } else if (userSettings === 'true') { 425 document.body.classList.add('dark-mode'); 426 } 427 if (themeToggleButton) { 428 themeToggleButton.hidden = false; 429 themeToggleButton.addEventListener('click', function() { 430 sessionStorage.setItem( 431 kCustomPreference, 432 document.body.classList.toggle('dark-mode') 433 ); 434 }); 435 } 436 } 437 </script> 438</body> 439</html> 440