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v18.20.1 documentation</h1> 1001cb0ef41Sopenharmony_ci <button class="theme-toggle-btn" id="theme-toggle-btn" title="Toggle dark mode/light mode" aria-label="Toggle dark mode/light mode" hidden> 1011cb0ef41Sopenharmony_ci <svg xmlns="http://www.w3.org/2000/svg" class="icon dark-icon" height="24" width="24"> 1021cb0ef41Sopenharmony_ci <path fill="none" d="M0 0h24v24H0z" /> 1031cb0ef41Sopenharmony_ci <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"/> 1041cb0ef41Sopenharmony_ci <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"/> 1051cb0ef41Sopenharmony_ci </svg> 1061cb0ef41Sopenharmony_ci <svg xmlns="http://www.w3.org/2000/svg" class="icon light-icon" height="24" width="24"> 1071cb0ef41Sopenharmony_ci <path d="M0 0h24v24H0z" 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1221cb0ef41Sopenharmony_ci <div class="picker"><div class="toc"><ul> 1231cb0ef41Sopenharmony_ci<li><span class="stability_2"><a href="#modules-commonjs-modules">Modules: CommonJS modules</a></span> 1241cb0ef41Sopenharmony_ci<ul> 1251cb0ef41Sopenharmony_ci<li><a href="#enabling">Enabling</a></li> 1261cb0ef41Sopenharmony_ci<li><a href="#accessing-the-main-module">Accessing the main module</a></li> 1271cb0ef41Sopenharmony_ci<li><a href="#package-manager-tips">Package manager tips</a></li> 1281cb0ef41Sopenharmony_ci<li><a href="#the-mjs-extension">The <code>.mjs</code> extension</a></li> 1291cb0ef41Sopenharmony_ci<li><a href="#all-together">All together</a></li> 1301cb0ef41Sopenharmony_ci<li><a href="#caching">Caching</a> 1311cb0ef41Sopenharmony_ci<ul> 1321cb0ef41Sopenharmony_ci<li><a href="#module-caching-caveats">Module caching caveats</a></li> 1331cb0ef41Sopenharmony_ci</ul> 1341cb0ef41Sopenharmony_ci</li> 1351cb0ef41Sopenharmony_ci<li><a href="#core-modules">Core modules</a></li> 1361cb0ef41Sopenharmony_ci<li><a href="#cycles">Cycles</a></li> 1371cb0ef41Sopenharmony_ci<li><a href="#file-modules">File modules</a></li> 1381cb0ef41Sopenharmony_ci<li><span class="stability_3"><a href="#folders-as-modules">Folders as modules</a></span></li> 1391cb0ef41Sopenharmony_ci<li><a href="#loading-from-node_modules-folders">Loading from <code>node_modules</code> folders</a></li> 1401cb0ef41Sopenharmony_ci<li><a href="#loading-from-the-global-folders">Loading from the global folders</a></li> 1411cb0ef41Sopenharmony_ci<li><a href="#the-module-wrapper">The module wrapper</a></li> 1421cb0ef41Sopenharmony_ci<li><a href="#the-module-scope">The module scope</a> 1431cb0ef41Sopenharmony_ci<ul> 1441cb0ef41Sopenharmony_ci<li><a href="#__dirname"><code>__dirname</code></a></li> 1451cb0ef41Sopenharmony_ci<li><a href="#__filename"><code>__filename</code></a></li> 1461cb0ef41Sopenharmony_ci<li><a href="#exports"><code>exports</code></a></li> 1471cb0ef41Sopenharmony_ci<li><a href="#module"><code>module</code></a></li> 1481cb0ef41Sopenharmony_ci<li><a href="#requireid"><code>require(id)</code></a> 1491cb0ef41Sopenharmony_ci<ul> 1501cb0ef41Sopenharmony_ci<li><a href="#requirecache"><code>require.cache</code></a></li> 1511cb0ef41Sopenharmony_ci<li><span class="stability_0"><a href="#requireextensions"><code>require.extensions</code></a></span></li> 1521cb0ef41Sopenharmony_ci<li><a href="#requiremain"><code>require.main</code></a></li> 1531cb0ef41Sopenharmony_ci<li><a href="#requireresolverequest-options"><code>require.resolve(request[, options])</code></a> 1541cb0ef41Sopenharmony_ci<ul> 1551cb0ef41Sopenharmony_ci<li><a href="#requireresolvepathsrequest"><code>require.resolve.paths(request)</code></a></li> 1561cb0ef41Sopenharmony_ci</ul> 1571cb0ef41Sopenharmony_ci</li> 1581cb0ef41Sopenharmony_ci</ul> 1591cb0ef41Sopenharmony_ci</li> 1601cb0ef41Sopenharmony_ci</ul> 1611cb0ef41Sopenharmony_ci</li> 1621cb0ef41Sopenharmony_ci<li><a href="#the-module-object">The <code>module</code> object</a> 1631cb0ef41Sopenharmony_ci<ul> 1641cb0ef41Sopenharmony_ci<li><a href="#modulechildren"><code>module.children</code></a></li> 1651cb0ef41Sopenharmony_ci<li><a href="#moduleexports"><code>module.exports</code></a> 1661cb0ef41Sopenharmony_ci<ul> 1671cb0ef41Sopenharmony_ci<li><a href="#exports-shortcut"><code>exports</code> shortcut</a></li> 1681cb0ef41Sopenharmony_ci</ul> 1691cb0ef41Sopenharmony_ci</li> 1701cb0ef41Sopenharmony_ci<li><a href="#modulefilename"><code>module.filename</code></a></li> 1711cb0ef41Sopenharmony_ci<li><a href="#moduleid"><code>module.id</code></a></li> 1721cb0ef41Sopenharmony_ci<li><a href="#moduleispreloading"><code>module.isPreloading</code></a></li> 1731cb0ef41Sopenharmony_ci<li><a href="#moduleloaded"><code>module.loaded</code></a></li> 1741cb0ef41Sopenharmony_ci<li><span class="stability_0"><a href="#moduleparent"><code>module.parent</code></a></span></li> 1751cb0ef41Sopenharmony_ci<li><a href="#modulepath"><code>module.path</code></a></li> 1761cb0ef41Sopenharmony_ci<li><a href="#modulepaths"><code>module.paths</code></a></li> 1771cb0ef41Sopenharmony_ci<li><a href="#modulerequireid"><code>module.require(id)</code></a></li> 1781cb0ef41Sopenharmony_ci</ul> 1791cb0ef41Sopenharmony_ci</li> 1801cb0ef41Sopenharmony_ci<li><a href="#the-module-object_1">The <code>Module</code> object</a></li> 1811cb0ef41Sopenharmony_ci<li><a href="#source-map-v3-support">Source map v3 support</a></li> 1821cb0ef41Sopenharmony_ci</ul> 1831cb0ef41Sopenharmony_ci</li> 1841cb0ef41Sopenharmony_ci</ul></div></div> 1851cb0ef41Sopenharmony_ci </li> 1861cb0ef41Sopenharmony_ci 1871cb0ef41Sopenharmony_ci 1881cb0ef41Sopenharmony_ci <li class="picker-header"> 1891cb0ef41Sopenharmony_ci <a href="#"> 1901cb0ef41Sopenharmony_ci <span class="collapsed-arrow">►</span><span class="expanded-arrow">▼</span> 1911cb0ef41Sopenharmony_ci Index 1921cb0ef41Sopenharmony_ci </a> 1931cb0ef41Sopenharmony_ci 1941cb0ef41Sopenharmony_ci <div class="picker"><ul> 1951cb0ef41Sopenharmony_ci<li><a href="documentation.html" class="nav-documentation">About this documentation</a></li> 1961cb0ef41Sopenharmony_ci<li><a href="synopsis.html" class="nav-synopsis">Usage and example</a></li> 1971cb0ef41Sopenharmony_ci 1981cb0ef41Sopenharmony_ci <li> 1991cb0ef41Sopenharmony_ci <a href="index.html">Index</a> 2001cb0ef41Sopenharmony_ci </li> 2011cb0ef41Sopenharmony_ci </ul> 2021cb0ef41Sopenharmony_ci 2031cb0ef41Sopenharmony_ci<hr class="line"> 2041cb0ef41Sopenharmony_ci<ul> 2051cb0ef41Sopenharmony_ci<li><a href="assert.html" class="nav-assert">Assertion testing</a></li> 2061cb0ef41Sopenharmony_ci<li><a href="async_context.html" class="nav-async_context">Asynchronous context tracking</a></li> 2071cb0ef41Sopenharmony_ci<li><a href="async_hooks.html" class="nav-async_hooks">Async hooks</a></li> 2081cb0ef41Sopenharmony_ci<li><a href="buffer.html" class="nav-buffer">Buffer</a></li> 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href="https://nodejs.org/docs/latest-v21.x/api/modules.html">21.x</a></li> 2791cb0ef41Sopenharmony_ci<li><a href="https://nodejs.org/docs/latest-v20.x/api/modules.html">20.x <b>LTS</b></a></li> 2801cb0ef41Sopenharmony_ci<li><a href="https://nodejs.org/docs/latest-v19.x/api/modules.html">19.x</a></li> 2811cb0ef41Sopenharmony_ci<li><a href="https://nodejs.org/docs/latest-v18.x/api/modules.html">18.x <b>LTS</b></a></li> 2821cb0ef41Sopenharmony_ci<li><a href="https://nodejs.org/docs/latest-v17.x/api/modules.html">17.x</a></li> 2831cb0ef41Sopenharmony_ci<li><a href="https://nodejs.org/docs/latest-v16.x/api/modules.html">16.x</a></li> 2841cb0ef41Sopenharmony_ci<li><a href="https://nodejs.org/docs/latest-v15.x/api/modules.html">15.x</a></li> 2851cb0ef41Sopenharmony_ci<li><a href="https://nodejs.org/docs/latest-v14.x/api/modules.html">14.x</a></li> 2861cb0ef41Sopenharmony_ci<li><a href="https://nodejs.org/docs/latest-v13.x/api/modules.html">13.x</a></li> 2871cb0ef41Sopenharmony_ci<li><a href="https://nodejs.org/docs/latest-v12.x/api/modules.html">12.x</a></li> 2881cb0ef41Sopenharmony_ci<li><a href="https://nodejs.org/docs/latest-v11.x/api/modules.html">11.x</a></li> 2891cb0ef41Sopenharmony_ci<li><a href="https://nodejs.org/docs/latest-v10.x/api/modules.html">10.x</a></li> 2901cb0ef41Sopenharmony_ci<li><a href="https://nodejs.org/docs/latest-v9.x/api/modules.html">9.x</a></li> 2911cb0ef41Sopenharmony_ci<li><a href="https://nodejs.org/docs/latest-v8.x/api/modules.html">8.x</a></li> 2921cb0ef41Sopenharmony_ci<li><a href="https://nodejs.org/docs/latest-v7.x/api/modules.html">7.x</a></li> 2931cb0ef41Sopenharmony_ci<li><a href="https://nodejs.org/docs/latest-v6.x/api/modules.html">6.x</a></li> 2941cb0ef41Sopenharmony_ci<li><a href="https://nodejs.org/docs/latest-v5.x/api/modules.html">5.x</a></li> 2951cb0ef41Sopenharmony_ci<li><a href="https://nodejs.org/docs/latest-v4.x/api/modules.html">4.x</a></li> 2961cb0ef41Sopenharmony_ci<li><a href="https://nodejs.org/docs/latest-v0.12.x/api/modules.html">0.12.x</a></li> 2971cb0ef41Sopenharmony_ci<li><a href="https://nodejs.org/docs/latest-v0.10.x/api/modules.html">0.10.x</a></li></ol></div> 2981cb0ef41Sopenharmony_ci </li> 2991cb0ef41Sopenharmony_ci 3001cb0ef41Sopenharmony_ci <li class="picker-header"> 3011cb0ef41Sopenharmony_ci <a href="#"> 3021cb0ef41Sopenharmony_ci <span class="collapsed-arrow">►</span><span class="expanded-arrow">▼</span> 3031cb0ef41Sopenharmony_ci Options 3041cb0ef41Sopenharmony_ci </a> 3051cb0ef41Sopenharmony_ci 3061cb0ef41Sopenharmony_ci <div class="picker"> 3071cb0ef41Sopenharmony_ci <ul> 3081cb0ef41Sopenharmony_ci <li> 3091cb0ef41Sopenharmony_ci <a href="all.html">View on single page</a> 3101cb0ef41Sopenharmony_ci </li> 3111cb0ef41Sopenharmony_ci <li> 3121cb0ef41Sopenharmony_ci <a href="modules.json">View as JSON</a> 3131cb0ef41Sopenharmony_ci </li> 3141cb0ef41Sopenharmony_ci <li class="edit_on_github"><a href="https://github.com/nodejs/node/edit/main/doc/api/modules.md">Edit on GitHub</a></li> 3151cb0ef41Sopenharmony_ci </ul> 3161cb0ef41Sopenharmony_ci </div> 3171cb0ef41Sopenharmony_ci </li> 3181cb0ef41Sopenharmony_ci </ul> 3191cb0ef41Sopenharmony_ci </div> 3201cb0ef41Sopenharmony_ci <hr> 3211cb0ef41Sopenharmony_ci </header> 3221cb0ef41Sopenharmony_ci 3231cb0ef41Sopenharmony_ci <details id="toc" open><summary>Table of contents</summary><ul> 3241cb0ef41Sopenharmony_ci<li><span class="stability_2"><a href="#modules-commonjs-modules">Modules: CommonJS modules</a></span> 3251cb0ef41Sopenharmony_ci<ul> 3261cb0ef41Sopenharmony_ci<li><a href="#enabling">Enabling</a></li> 3271cb0ef41Sopenharmony_ci<li><a href="#accessing-the-main-module">Accessing the main module</a></li> 3281cb0ef41Sopenharmony_ci<li><a href="#package-manager-tips">Package manager tips</a></li> 3291cb0ef41Sopenharmony_ci<li><a href="#the-mjs-extension">The <code>.mjs</code> extension</a></li> 3301cb0ef41Sopenharmony_ci<li><a href="#all-together">All together</a></li> 3311cb0ef41Sopenharmony_ci<li><a href="#caching">Caching</a> 3321cb0ef41Sopenharmony_ci<ul> 3331cb0ef41Sopenharmony_ci<li><a href="#module-caching-caveats">Module caching caveats</a></li> 3341cb0ef41Sopenharmony_ci</ul> 3351cb0ef41Sopenharmony_ci</li> 3361cb0ef41Sopenharmony_ci<li><a href="#core-modules">Core modules</a></li> 3371cb0ef41Sopenharmony_ci<li><a href="#cycles">Cycles</a></li> 3381cb0ef41Sopenharmony_ci<li><a href="#file-modules">File modules</a></li> 3391cb0ef41Sopenharmony_ci<li><span class="stability_3"><a href="#folders-as-modules">Folders as modules</a></span></li> 3401cb0ef41Sopenharmony_ci<li><a href="#loading-from-node_modules-folders">Loading from <code>node_modules</code> folders</a></li> 3411cb0ef41Sopenharmony_ci<li><a href="#loading-from-the-global-folders">Loading from the global folders</a></li> 3421cb0ef41Sopenharmony_ci<li><a href="#the-module-wrapper">The module wrapper</a></li> 3431cb0ef41Sopenharmony_ci<li><a href="#the-module-scope">The module scope</a> 3441cb0ef41Sopenharmony_ci<ul> 3451cb0ef41Sopenharmony_ci<li><a href="#__dirname"><code>__dirname</code></a></li> 3461cb0ef41Sopenharmony_ci<li><a href="#__filename"><code>__filename</code></a></li> 3471cb0ef41Sopenharmony_ci<li><a href="#exports"><code>exports</code></a></li> 3481cb0ef41Sopenharmony_ci<li><a href="#module"><code>module</code></a></li> 3491cb0ef41Sopenharmony_ci<li><a href="#requireid"><code>require(id)</code></a> 3501cb0ef41Sopenharmony_ci<ul> 3511cb0ef41Sopenharmony_ci<li><a href="#requirecache"><code>require.cache</code></a></li> 3521cb0ef41Sopenharmony_ci<li><span class="stability_0"><a href="#requireextensions"><code>require.extensions</code></a></span></li> 3531cb0ef41Sopenharmony_ci<li><a href="#requiremain"><code>require.main</code></a></li> 3541cb0ef41Sopenharmony_ci<li><a href="#requireresolverequest-options"><code>require.resolve(request[, options])</code></a> 3551cb0ef41Sopenharmony_ci<ul> 3561cb0ef41Sopenharmony_ci<li><a href="#requireresolvepathsrequest"><code>require.resolve.paths(request)</code></a></li> 3571cb0ef41Sopenharmony_ci</ul> 3581cb0ef41Sopenharmony_ci</li> 3591cb0ef41Sopenharmony_ci</ul> 3601cb0ef41Sopenharmony_ci</li> 3611cb0ef41Sopenharmony_ci</ul> 3621cb0ef41Sopenharmony_ci</li> 3631cb0ef41Sopenharmony_ci<li><a href="#the-module-object">The <code>module</code> object</a> 3641cb0ef41Sopenharmony_ci<ul> 3651cb0ef41Sopenharmony_ci<li><a href="#modulechildren"><code>module.children</code></a></li> 3661cb0ef41Sopenharmony_ci<li><a href="#moduleexports"><code>module.exports</code></a> 3671cb0ef41Sopenharmony_ci<ul> 3681cb0ef41Sopenharmony_ci<li><a href="#exports-shortcut"><code>exports</code> shortcut</a></li> 3691cb0ef41Sopenharmony_ci</ul> 3701cb0ef41Sopenharmony_ci</li> 3711cb0ef41Sopenharmony_ci<li><a href="#modulefilename"><code>module.filename</code></a></li> 3721cb0ef41Sopenharmony_ci<li><a href="#moduleid"><code>module.id</code></a></li> 3731cb0ef41Sopenharmony_ci<li><a href="#moduleispreloading"><code>module.isPreloading</code></a></li> 3741cb0ef41Sopenharmony_ci<li><a href="#moduleloaded"><code>module.loaded</code></a></li> 3751cb0ef41Sopenharmony_ci<li><span class="stability_0"><a href="#moduleparent"><code>module.parent</code></a></span></li> 3761cb0ef41Sopenharmony_ci<li><a href="#modulepath"><code>module.path</code></a></li> 3771cb0ef41Sopenharmony_ci<li><a href="#modulepaths"><code>module.paths</code></a></li> 3781cb0ef41Sopenharmony_ci<li><a href="#modulerequireid"><code>module.require(id)</code></a></li> 3791cb0ef41Sopenharmony_ci</ul> 3801cb0ef41Sopenharmony_ci</li> 3811cb0ef41Sopenharmony_ci<li><a href="#the-module-object_1">The <code>Module</code> object</a></li> 3821cb0ef41Sopenharmony_ci<li><a href="#source-map-v3-support">Source map v3 support</a></li> 3831cb0ef41Sopenharmony_ci</ul> 3841cb0ef41Sopenharmony_ci</li> 3851cb0ef41Sopenharmony_ci</ul></details> 3861cb0ef41Sopenharmony_ci 3871cb0ef41Sopenharmony_ci <div id="apicontent"> 3881cb0ef41Sopenharmony_ci <h2>Modules: CommonJS modules<span><a class="mark" href="#modules-commonjs-modules" id="modules-commonjs-modules">#</a></span><a aria-hidden="true" class="legacy" id="modules_modules_commonjs_modules"></a></h2> 3891cb0ef41Sopenharmony_ci 3901cb0ef41Sopenharmony_ci<p></p><div class="api_stability api_stability_2"><a href="documentation.html#stability-index">Stability: 2</a> - Stable</div><p></p> 3911cb0ef41Sopenharmony_ci 3921cb0ef41Sopenharmony_ci<p>CommonJS modules are the original way to package JavaScript code for Node.js. 3931cb0ef41Sopenharmony_ciNode.js also supports the <a href="esm.html">ECMAScript modules</a> standard used by browsers 3941cb0ef41Sopenharmony_ciand other JavaScript runtimes.</p> 3951cb0ef41Sopenharmony_ci<p>In Node.js, each file is treated as a separate module. For 3961cb0ef41Sopenharmony_ciexample, consider a file named <code>foo.js</code>:</p> 3971cb0ef41Sopenharmony_ci<pre><code class="language-js"><span class="hljs-keyword">const</span> circle = <span class="hljs-built_in">require</span>(<span class="hljs-string">'./circle.js'</span>); 3981cb0ef41Sopenharmony_ci<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-string">`The area of a circle of radius 4 is <span class="hljs-subst">${circle.area(<span class="hljs-number">4</span>)}</span>`</span>);</code> <button class="copy-button">copy</button></pre> 3991cb0ef41Sopenharmony_ci<p>On the first line, <code>foo.js</code> loads the module <code>circle.js</code> that is in the same 4001cb0ef41Sopenharmony_cidirectory as <code>foo.js</code>.</p> 4011cb0ef41Sopenharmony_ci<p>Here are the contents of <code>circle.js</code>:</p> 4021cb0ef41Sopenharmony_ci<pre><code class="language-js"><span class="hljs-keyword">const</span> { <span class="hljs-variable constant_">PI</span> } = <span class="hljs-title class_">Math</span>; 4031cb0ef41Sopenharmony_ci 4041cb0ef41Sopenharmony_ci<span class="hljs-built_in">exports</span>.<span class="hljs-property">area</span> = <span class="hljs-function">(<span class="hljs-params">r</span>) =></span> <span class="hljs-variable constant_">PI</span> * r ** <span class="hljs-number">2</span>; 4051cb0ef41Sopenharmony_ci 4061cb0ef41Sopenharmony_ci<span class="hljs-built_in">exports</span>.<span class="hljs-property">circumference</span> = <span class="hljs-function">(<span class="hljs-params">r</span>) =></span> <span class="hljs-number">2</span> * <span class="hljs-variable constant_">PI</span> * r;</code> <button class="copy-button">copy</button></pre> 4071cb0ef41Sopenharmony_ci<p>The module <code>circle.js</code> has exported the functions <code>area()</code> and 4081cb0ef41Sopenharmony_ci<code>circumference()</code>. Functions and objects are added to the root of a module 4091cb0ef41Sopenharmony_ciby specifying additional properties on the special <code>exports</code> object.</p> 4101cb0ef41Sopenharmony_ci<p>Variables local to the module will be private, because the module is wrapped 4111cb0ef41Sopenharmony_ciin a function by Node.js (see <a href="#the-module-wrapper">module wrapper</a>). 4121cb0ef41Sopenharmony_ciIn this example, the variable <code>PI</code> is private to <code>circle.js</code>.</p> 4131cb0ef41Sopenharmony_ci<p>The <code>module.exports</code> property can be assigned a new value (such as a function 4141cb0ef41Sopenharmony_cior object).</p> 4151cb0ef41Sopenharmony_ci<p>Below, <code>bar.js</code> makes use of the <code>square</code> module, which exports a Square class:</p> 4161cb0ef41Sopenharmony_ci<pre><code class="language-js"><span class="hljs-keyword">const</span> <span class="hljs-title class_">Square</span> = <span class="hljs-built_in">require</span>(<span class="hljs-string">'./square.js'</span>); 4171cb0ef41Sopenharmony_ci<span class="hljs-keyword">const</span> mySquare = <span class="hljs-keyword">new</span> <span class="hljs-title class_">Square</span>(<span class="hljs-number">2</span>); 4181cb0ef41Sopenharmony_ci<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-string">`The area of mySquare is <span class="hljs-subst">${mySquare.area()}</span>`</span>);</code> <button class="copy-button">copy</button></pre> 4191cb0ef41Sopenharmony_ci<p>The <code>square</code> module is defined in <code>square.js</code>:</p> 4201cb0ef41Sopenharmony_ci<pre><code class="language-js"><span class="hljs-comment">// Assigning to exports will not modify module, must use module.exports</span> 4211cb0ef41Sopenharmony_ci<span class="hljs-variable language_">module</span>.<span class="hljs-property">exports</span> = <span class="hljs-keyword">class</span> <span class="hljs-title class_">Square</span> { 4221cb0ef41Sopenharmony_ci <span class="hljs-title function_">constructor</span>(<span class="hljs-params">width</span>) { 4231cb0ef41Sopenharmony_ci <span class="hljs-variable language_">this</span>.<span class="hljs-property">width</span> = width; 4241cb0ef41Sopenharmony_ci } 4251cb0ef41Sopenharmony_ci 4261cb0ef41Sopenharmony_ci <span class="hljs-title function_">area</span>(<span class="hljs-params"></span>) { 4271cb0ef41Sopenharmony_ci <span class="hljs-keyword">return</span> <span class="hljs-variable language_">this</span>.<span class="hljs-property">width</span> ** <span class="hljs-number">2</span>; 4281cb0ef41Sopenharmony_ci } 4291cb0ef41Sopenharmony_ci};</code> <button class="copy-button">copy</button></pre> 4301cb0ef41Sopenharmony_ci<p>The CommonJS module system is implemented in the <a href="module.html"><code>module</code> core module</a>.</p> 4311cb0ef41Sopenharmony_ci<section><h3>Enabling<span><a class="mark" href="#enabling" id="enabling">#</a></span><a aria-hidden="true" class="legacy" id="modules_enabling"></a></h3> 4321cb0ef41Sopenharmony_ci 4331cb0ef41Sopenharmony_ci<p>Node.js has two module systems: CommonJS modules and <a href="esm.html">ECMAScript modules</a>.</p> 4341cb0ef41Sopenharmony_ci<p>By default, Node.js will treat the following as CommonJS modules:</p> 4351cb0ef41Sopenharmony_ci<ul> 4361cb0ef41Sopenharmony_ci<li> 4371cb0ef41Sopenharmony_ci<p>Files with a <code>.cjs</code> extension;</p> 4381cb0ef41Sopenharmony_ci</li> 4391cb0ef41Sopenharmony_ci<li> 4401cb0ef41Sopenharmony_ci<p>Files with a <code>.js</code> extension when the nearest parent <code>package.json</code> file 4411cb0ef41Sopenharmony_cicontains a top-level field <a href="packages.html#type"><code>"type"</code></a> with a value of <code>"commonjs"</code>.</p> 4421cb0ef41Sopenharmony_ci</li> 4431cb0ef41Sopenharmony_ci<li> 4441cb0ef41Sopenharmony_ci<p>Files with a <code>.js</code> extension when the nearest parent <code>package.json</code> file 4451cb0ef41Sopenharmony_cidoesn't contain a top-level field <a href="packages.html#type"><code>"type"</code></a>. Package authors should include 4461cb0ef41Sopenharmony_cithe <a href="packages.html#type"><code>"type"</code></a> field, even in packages where all sources are CommonJS. Being 4471cb0ef41Sopenharmony_ciexplicit about the <code>type</code> of the package will make things easier for build 4481cb0ef41Sopenharmony_citools and loaders to determine how the files in the package should be 4491cb0ef41Sopenharmony_ciinterpreted.</p> 4501cb0ef41Sopenharmony_ci</li> 4511cb0ef41Sopenharmony_ci<li> 4521cb0ef41Sopenharmony_ci<p>Files with an extension that is not <code>.mjs</code>, <code>.cjs</code>, <code>.json</code>, <code>.node</code>, or <code>.js</code> 4531cb0ef41Sopenharmony_ci(when the nearest parent <code>package.json</code> file contains a top-level field 4541cb0ef41Sopenharmony_ci<a href="packages.html#type"><code>"type"</code></a> with a value of <code>"module"</code>, those files will be recognized as 4551cb0ef41Sopenharmony_ciCommonJS modules only if they are being included via <code>require()</code>, not when 4561cb0ef41Sopenharmony_ciused as the command-line entry point of the program).</p> 4571cb0ef41Sopenharmony_ci</li> 4581cb0ef41Sopenharmony_ci</ul> 4591cb0ef41Sopenharmony_ci<p>See <a href="packages.html#determining-module-system">Determining module system</a> for more details.</p> 4601cb0ef41Sopenharmony_ci<p>Calling <code>require()</code> always use the CommonJS module loader. Calling <code>import()</code> 4611cb0ef41Sopenharmony_cialways use the ECMAScript module loader.</p> 4621cb0ef41Sopenharmony_ci</section><section><h3>Accessing the main module<span><a class="mark" href="#accessing-the-main-module" id="accessing-the-main-module">#</a></span><a aria-hidden="true" class="legacy" id="modules_accessing_the_main_module"></a></h3> 4631cb0ef41Sopenharmony_ci 4641cb0ef41Sopenharmony_ci<p>When a file is run directly from Node.js, <code>require.main</code> is set to its 4651cb0ef41Sopenharmony_ci<code>module</code>. That means that it is possible to determine whether a file has been 4661cb0ef41Sopenharmony_cirun directly by testing <code>require.main === module</code>.</p> 4671cb0ef41Sopenharmony_ci<p>For a file <code>foo.js</code>, this will be <code>true</code> if run via <code>node foo.js</code>, but 4681cb0ef41Sopenharmony_ci<code>false</code> if run by <code>require('./foo')</code>.</p> 4691cb0ef41Sopenharmony_ci<p>When the entry point is not a CommonJS module, <code>require.main</code> is <code>undefined</code>, 4701cb0ef41Sopenharmony_ciand the main module is out of reach.</p> 4711cb0ef41Sopenharmony_ci</section><section><h3>Package manager tips<span><a class="mark" href="#package-manager-tips" id="package-manager-tips">#</a></span><a aria-hidden="true" class="legacy" id="modules_package_manager_tips"></a></h3> 4721cb0ef41Sopenharmony_ci 4731cb0ef41Sopenharmony_ci<p>The semantics of the Node.js <code>require()</code> function were designed to be general 4741cb0ef41Sopenharmony_cienough to support reasonable directory structures. Package manager programs 4751cb0ef41Sopenharmony_cisuch as <code>dpkg</code>, <code>rpm</code>, and <code>npm</code> will hopefully find it possible to build 4761cb0ef41Sopenharmony_cinative packages from Node.js modules without modification.</p> 4771cb0ef41Sopenharmony_ci<p>Below we give a suggested directory structure that could work:</p> 4781cb0ef41Sopenharmony_ci<p>Let's say that we wanted to have the folder at 4791cb0ef41Sopenharmony_ci<code>/usr/lib/node/<some-package>/<some-version></code> hold the contents of a 4801cb0ef41Sopenharmony_cispecific version of a package.</p> 4811cb0ef41Sopenharmony_ci<p>Packages can depend on one another. In order to install package <code>foo</code>, it 4821cb0ef41Sopenharmony_cimay be necessary to install a specific version of package <code>bar</code>. The <code>bar</code> 4831cb0ef41Sopenharmony_cipackage may itself have dependencies, and in some cases, these may even collide 4841cb0ef41Sopenharmony_cior form cyclic dependencies.</p> 4851cb0ef41Sopenharmony_ci<p>Because Node.js looks up the <code>realpath</code> of any modules it loads (that is, it 4861cb0ef41Sopenharmony_ciresolves symlinks) and then <a href="#loading-from-node_modules-folders">looks for their dependencies in <code>node_modules</code> folders</a>, 4871cb0ef41Sopenharmony_cithis situation can be resolved with the following architecture:</p> 4881cb0ef41Sopenharmony_ci<ul> 4891cb0ef41Sopenharmony_ci<li><code>/usr/lib/node/foo/1.2.3/</code>: Contents of the <code>foo</code> package, version 1.2.3.</li> 4901cb0ef41Sopenharmony_ci<li><code>/usr/lib/node/bar/4.3.2/</code>: Contents of the <code>bar</code> package that <code>foo</code> depends 4911cb0ef41Sopenharmony_cion.</li> 4921cb0ef41Sopenharmony_ci<li><code>/usr/lib/node/foo/1.2.3/node_modules/bar</code>: Symbolic link to 4931cb0ef41Sopenharmony_ci<code>/usr/lib/node/bar/4.3.2/</code>.</li> 4941cb0ef41Sopenharmony_ci<li><code>/usr/lib/node/bar/4.3.2/node_modules/*</code>: Symbolic links to the packages that 4951cb0ef41Sopenharmony_ci<code>bar</code> depends on.</li> 4961cb0ef41Sopenharmony_ci</ul> 4971cb0ef41Sopenharmony_ci<p>Thus, even if a cycle is encountered, or if there are dependency 4981cb0ef41Sopenharmony_ciconflicts, every module will be able to get a version of its dependency 4991cb0ef41Sopenharmony_cithat it can use.</p> 5001cb0ef41Sopenharmony_ci<p>When the code in the <code>foo</code> package does <code>require('bar')</code>, it will get the 5011cb0ef41Sopenharmony_civersion that is symlinked into <code>/usr/lib/node/foo/1.2.3/node_modules/bar</code>. 5021cb0ef41Sopenharmony_ciThen, when the code in the <code>bar</code> package calls <code>require('quux')</code>, it'll get 5031cb0ef41Sopenharmony_cithe version that is symlinked into 5041cb0ef41Sopenharmony_ci<code>/usr/lib/node/bar/4.3.2/node_modules/quux</code>.</p> 5051cb0ef41Sopenharmony_ci<p>Furthermore, to make the module lookup process even more optimal, rather 5061cb0ef41Sopenharmony_cithan putting packages directly in <code>/usr/lib/node</code>, we could put them in 5071cb0ef41Sopenharmony_ci<code>/usr/lib/node_modules/<name>/<version></code>. Then Node.js will not bother 5081cb0ef41Sopenharmony_cilooking for missing dependencies in <code>/usr/node_modules</code> or <code>/node_modules</code>.</p> 5091cb0ef41Sopenharmony_ci<p>In order to make modules available to the Node.js REPL, it might be useful to 5101cb0ef41Sopenharmony_cialso add the <code>/usr/lib/node_modules</code> folder to the <code>$NODE_PATH</code> environment 5111cb0ef41Sopenharmony_civariable. Since the module lookups using <code>node_modules</code> folders are all 5121cb0ef41Sopenharmony_cirelative, and based on the real path of the files making the calls to 5131cb0ef41Sopenharmony_ci<code>require()</code>, the packages themselves can be anywhere.</p> 5141cb0ef41Sopenharmony_ci</section><section><h3>The <code>.mjs</code> extension<span><a class="mark" href="#the-mjs-extension" id="the-mjs-extension">#</a></span><a aria-hidden="true" class="legacy" id="modules_the_mjs_extension"></a></h3> 5151cb0ef41Sopenharmony_ci<p>Due to the synchronous nature of <code>require()</code>, it is not possible to use it to 5161cb0ef41Sopenharmony_ciload ECMAScript module files. Attempting to do so will throw a 5171cb0ef41Sopenharmony_ci<a href="errors.html#err_require_esm"><code>ERR_REQUIRE_ESM</code></a> error. Use <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/import"><code>import()</code></a> instead.</p> 5181cb0ef41Sopenharmony_ci<p>The <code>.mjs</code> extension is reserved for <a href="esm.html">ECMAScript Modules</a> which cannot be 5191cb0ef41Sopenharmony_ciloaded via <code>require()</code>. See <a href="packages.html#determining-module-system">Determining module system</a> section for more info 5201cb0ef41Sopenharmony_ciregarding which files are parsed as ECMAScript modules.</p> 5211cb0ef41Sopenharmony_ci</section><section><h3>All together<span><a class="mark" href="#all-together" id="all-together">#</a></span><a aria-hidden="true" class="legacy" id="modules_all_together"></a></h3> 5221cb0ef41Sopenharmony_ci 5231cb0ef41Sopenharmony_ci<p>To get the exact filename that will be loaded when <code>require()</code> is called, use 5241cb0ef41Sopenharmony_cithe <code>require.resolve()</code> function.</p> 5251cb0ef41Sopenharmony_ci<p>Putting together all of the above, here is the high-level algorithm 5261cb0ef41Sopenharmony_ciin pseudocode of what <code>require()</code> does:</p> 5271cb0ef41Sopenharmony_ci<pre>require(X) from module at path Y 5281cb0ef41Sopenharmony_ci1. If X is a core module, 5291cb0ef41Sopenharmony_ci a. return the core module 5301cb0ef41Sopenharmony_ci b. STOP 5311cb0ef41Sopenharmony_ci2. If X begins with '/' 5321cb0ef41Sopenharmony_ci a. set Y to be the file system root 5331cb0ef41Sopenharmony_ci3. If X begins with './' or '/' or '../' 5341cb0ef41Sopenharmony_ci a. LOAD_AS_FILE(Y + X) 5351cb0ef41Sopenharmony_ci b. LOAD_AS_DIRECTORY(Y + X) 5361cb0ef41Sopenharmony_ci c. THROW "not found" 5371cb0ef41Sopenharmony_ci4. If X begins with '#' 5381cb0ef41Sopenharmony_ci a. LOAD_PACKAGE_IMPORTS(X, dirname(Y)) 5391cb0ef41Sopenharmony_ci5. LOAD_PACKAGE_SELF(X, dirname(Y)) 5401cb0ef41Sopenharmony_ci6. LOAD_NODE_MODULES(X, dirname(Y)) 5411cb0ef41Sopenharmony_ci7. THROW "not found" 5421cb0ef41Sopenharmony_ci 5431cb0ef41Sopenharmony_ciLOAD_AS_FILE(X) 5441cb0ef41Sopenharmony_ci1. If X is a file, load X as its file extension format. STOP 5451cb0ef41Sopenharmony_ci2. If X.js is a file, load X.js as JavaScript text. STOP 5461cb0ef41Sopenharmony_ci3. If X.json is a file, parse X.json to a JavaScript Object. STOP 5471cb0ef41Sopenharmony_ci4. If X.node is a file, load X.node as binary addon. STOP 5481cb0ef41Sopenharmony_ci 5491cb0ef41Sopenharmony_ciLOAD_INDEX(X) 5501cb0ef41Sopenharmony_ci1. If X/index.js is a file, load X/index.js as JavaScript text. STOP 5511cb0ef41Sopenharmony_ci2. If X/index.json is a file, parse X/index.json to a JavaScript object. STOP 5521cb0ef41Sopenharmony_ci3. If X/index.node is a file, load X/index.node as binary addon. STOP 5531cb0ef41Sopenharmony_ci 5541cb0ef41Sopenharmony_ciLOAD_AS_DIRECTORY(X) 5551cb0ef41Sopenharmony_ci1. If X/package.json is a file, 5561cb0ef41Sopenharmony_ci a. Parse X/package.json, and look for "main" field. 5571cb0ef41Sopenharmony_ci b. If "main" is a falsy value, GOTO 2. 5581cb0ef41Sopenharmony_ci c. let M = X + (json main field) 5591cb0ef41Sopenharmony_ci d. LOAD_AS_FILE(M) 5601cb0ef41Sopenharmony_ci e. LOAD_INDEX(M) 5611cb0ef41Sopenharmony_ci f. LOAD_INDEX(X) DEPRECATED 5621cb0ef41Sopenharmony_ci g. THROW "not found" 5631cb0ef41Sopenharmony_ci2. LOAD_INDEX(X) 5641cb0ef41Sopenharmony_ci 5651cb0ef41Sopenharmony_ciLOAD_NODE_MODULES(X, START) 5661cb0ef41Sopenharmony_ci1. let DIRS = NODE_MODULES_PATHS(START) 5671cb0ef41Sopenharmony_ci2. for each DIR in DIRS: 5681cb0ef41Sopenharmony_ci a. LOAD_PACKAGE_EXPORTS(X, DIR) 5691cb0ef41Sopenharmony_ci b. LOAD_AS_FILE(DIR/X) 5701cb0ef41Sopenharmony_ci c. LOAD_AS_DIRECTORY(DIR/X) 5711cb0ef41Sopenharmony_ci 5721cb0ef41Sopenharmony_ciNODE_MODULES_PATHS(START) 5731cb0ef41Sopenharmony_ci1. let PARTS = path split(START) 5741cb0ef41Sopenharmony_ci2. let I = count of PARTS - 1 5751cb0ef41Sopenharmony_ci3. let DIRS = [] 5761cb0ef41Sopenharmony_ci4. while I >= 0, 5771cb0ef41Sopenharmony_ci a. if PARTS[I] = "node_modules" CONTINUE 5781cb0ef41Sopenharmony_ci b. DIR = path join(PARTS[0 .. I] + "node_modules") 5791cb0ef41Sopenharmony_ci c. DIRS = DIR + DIRS 5801cb0ef41Sopenharmony_ci d. let I = I - 1 5811cb0ef41Sopenharmony_ci5. return DIRS + GLOBAL_FOLDERS 5821cb0ef41Sopenharmony_ci 5831cb0ef41Sopenharmony_ciLOAD_PACKAGE_IMPORTS(X, DIR) 5841cb0ef41Sopenharmony_ci1. Find the closest package scope SCOPE to DIR. 5851cb0ef41Sopenharmony_ci2. If no scope was found, return. 5861cb0ef41Sopenharmony_ci3. If the SCOPE/package.json "imports" is null or undefined, return. 5871cb0ef41Sopenharmony_ci4. let MATCH = PACKAGE_IMPORTS_RESOLVE(X, pathToFileURL(SCOPE), 5881cb0ef41Sopenharmony_ci ["node", "require"]) <a href="esm.md#resolver-algorithm-specification">defined in the ESM resolver</a>. 5891cb0ef41Sopenharmony_ci5. RESOLVE_ESM_MATCH(MATCH). 5901cb0ef41Sopenharmony_ci 5911cb0ef41Sopenharmony_ciLOAD_PACKAGE_EXPORTS(X, DIR) 5921cb0ef41Sopenharmony_ci1. Try to interpret X as a combination of NAME and SUBPATH where the name 5931cb0ef41Sopenharmony_ci may have a @scope/ prefix and the subpath begins with a slash (`/`). 5941cb0ef41Sopenharmony_ci2. If X does not match this pattern or DIR/NAME/package.json is not a file, 5951cb0ef41Sopenharmony_ci return. 5961cb0ef41Sopenharmony_ci3. Parse DIR/NAME/package.json, and look for "exports" field. 5971cb0ef41Sopenharmony_ci4. If "exports" is null or undefined, return. 5981cb0ef41Sopenharmony_ci5. let MATCH = PACKAGE_EXPORTS_RESOLVE(pathToFileURL(DIR/NAME), "." + SUBPATH, 5991cb0ef41Sopenharmony_ci `package.json` "exports", ["node", "require"]) <a href="esm.md#resolver-algorithm-specification">defined in the ESM resolver</a>. 6001cb0ef41Sopenharmony_ci6. RESOLVE_ESM_MATCH(MATCH) 6011cb0ef41Sopenharmony_ci 6021cb0ef41Sopenharmony_ciLOAD_PACKAGE_SELF(X, DIR) 6031cb0ef41Sopenharmony_ci1. Find the closest package scope SCOPE to DIR. 6041cb0ef41Sopenharmony_ci2. If no scope was found, return. 6051cb0ef41Sopenharmony_ci3. If the SCOPE/package.json "exports" is null or undefined, return. 6061cb0ef41Sopenharmony_ci4. If the SCOPE/package.json "name" is not the first segment of X, return. 6071cb0ef41Sopenharmony_ci5. let MATCH = PACKAGE_EXPORTS_RESOLVE(pathToFileURL(SCOPE), 6081cb0ef41Sopenharmony_ci "." + X.slice("name".length), `package.json` "exports", ["node", "require"]) 6091cb0ef41Sopenharmony_ci <a href="esm.md#resolver-algorithm-specification">defined in the ESM resolver</a>. 6101cb0ef41Sopenharmony_ci6. RESOLVE_ESM_MATCH(MATCH) 6111cb0ef41Sopenharmony_ci 6121cb0ef41Sopenharmony_ciRESOLVE_ESM_MATCH(MATCH) 6131cb0ef41Sopenharmony_ci1. let RESOLVED_PATH = fileURLToPath(MATCH) 6141cb0ef41Sopenharmony_ci2. If the file at RESOLVED_PATH exists, load RESOLVED_PATH as its extension 6151cb0ef41Sopenharmony_ci format. STOP 6161cb0ef41Sopenharmony_ci3. THROW "not found" 6171cb0ef41Sopenharmony_ci</pre> 6181cb0ef41Sopenharmony_ci</section><section><h3>Caching<span><a class="mark" href="#caching" id="caching">#</a></span><a aria-hidden="true" class="legacy" id="modules_caching"></a></h3> 6191cb0ef41Sopenharmony_ci 6201cb0ef41Sopenharmony_ci<p>Modules are cached after the first time they are loaded. This means (among other 6211cb0ef41Sopenharmony_cithings) that every call to <code>require('foo')</code> will get exactly the same object 6221cb0ef41Sopenharmony_cireturned, if it would resolve to the same file.</p> 6231cb0ef41Sopenharmony_ci<p>Provided <code>require.cache</code> is not modified, multiple calls to <code>require('foo')</code> 6241cb0ef41Sopenharmony_ciwill not cause the module code to be executed multiple times. This is an 6251cb0ef41Sopenharmony_ciimportant feature. With it, "partially done" objects can be returned, thus 6261cb0ef41Sopenharmony_ciallowing transitive dependencies to be loaded even when they would cause cycles.</p> 6271cb0ef41Sopenharmony_ci<p>To have a module execute code multiple times, export a function, and call that 6281cb0ef41Sopenharmony_cifunction.</p> 6291cb0ef41Sopenharmony_ci<h4>Module caching caveats<span><a class="mark" href="#module-caching-caveats" id="module-caching-caveats">#</a></span><a aria-hidden="true" class="legacy" id="modules_module_caching_caveats"></a></h4> 6301cb0ef41Sopenharmony_ci 6311cb0ef41Sopenharmony_ci<p>Modules are cached based on their resolved filename. Since modules may resolve 6321cb0ef41Sopenharmony_cito a different filename based on the location of the calling module (loading 6331cb0ef41Sopenharmony_cifrom <code>node_modules</code> folders), it is not a <em>guarantee</em> that <code>require('foo')</code> will 6341cb0ef41Sopenharmony_cialways return the exact same object, if it would resolve to different files.</p> 6351cb0ef41Sopenharmony_ci<p>Additionally, on case-insensitive file systems or operating systems, different 6361cb0ef41Sopenharmony_ciresolved filenames can point to the same file, but the cache will still treat 6371cb0ef41Sopenharmony_cithem as different modules and will reload the file multiple times. For example, 6381cb0ef41Sopenharmony_ci<code>require('./foo')</code> and <code>require('./FOO')</code> return two different objects, 6391cb0ef41Sopenharmony_ciirrespective of whether or not <code>./foo</code> and <code>./FOO</code> are the same file.</p> 6401cb0ef41Sopenharmony_ci</section><section><h3>Core modules<span><a class="mark" href="#core-modules" id="core-modules">#</a></span><a aria-hidden="true" class="legacy" id="modules_core_modules"></a></h3> 6411cb0ef41Sopenharmony_ci 6421cb0ef41Sopenharmony_ci<div class="api_metadata"> 6431cb0ef41Sopenharmony_ci<details class="changelog"><summary>History</summary> 6441cb0ef41Sopenharmony_ci<table> 6451cb0ef41Sopenharmony_ci<tbody><tr><th>Version</th><th>Changes</th></tr> 6461cb0ef41Sopenharmony_ci<tr><td>v16.0.0, v14.18.0</td> 6471cb0ef41Sopenharmony_ci<td><p>Added <code>node:</code> import support to <code>require(...)</code>.</p></td></tr> 6481cb0ef41Sopenharmony_ci</tbody></table> 6491cb0ef41Sopenharmony_ci</details> 6501cb0ef41Sopenharmony_ci</div> 6511cb0ef41Sopenharmony_ci<p>Node.js has several modules compiled into the binary. These modules are 6521cb0ef41Sopenharmony_cidescribed in greater detail elsewhere in this documentation.</p> 6531cb0ef41Sopenharmony_ci<p>The core modules are defined within the Node.js source and are located in the 6541cb0ef41Sopenharmony_ci<code>lib/</code> folder.</p> 6551cb0ef41Sopenharmony_ci<p>Core modules can be identified using the <code>node:</code> prefix, in which case 6561cb0ef41Sopenharmony_ciit bypasses the <code>require</code> cache. For instance, <code>require('node:http')</code> will 6571cb0ef41Sopenharmony_cialways return the built in HTTP module, even if there is <code>require.cache</code> entry 6581cb0ef41Sopenharmony_ciby that name.</p> 6591cb0ef41Sopenharmony_ci<p>Some core modules are always preferentially loaded if their identifier is 6601cb0ef41Sopenharmony_cipassed to <code>require()</code>. For instance, <code>require('http')</code> will always 6611cb0ef41Sopenharmony_cireturn the built-in HTTP module, even if there is a file by that name. The list 6621cb0ef41Sopenharmony_ciof core modules that can be loaded without using the <code>node:</code> prefix is exposed 6631cb0ef41Sopenharmony_cias <a href="module.html#modulebuiltinmodules"><code>module.builtinModules</code></a>.</p> 6641cb0ef41Sopenharmony_ci</section><section><h3>Cycles<span><a class="mark" href="#cycles" id="cycles">#</a></span><a aria-hidden="true" class="legacy" id="modules_cycles"></a></h3> 6651cb0ef41Sopenharmony_ci 6661cb0ef41Sopenharmony_ci<p>When there are circular <code>require()</code> calls, a module might not have finished 6671cb0ef41Sopenharmony_ciexecuting when it is returned.</p> 6681cb0ef41Sopenharmony_ci<p>Consider this situation:</p> 6691cb0ef41Sopenharmony_ci<p><code>a.js</code>:</p> 6701cb0ef41Sopenharmony_ci<pre><code class="language-js"><span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-string">'a starting'</span>); 6711cb0ef41Sopenharmony_ci<span class="hljs-built_in">exports</span>.<span class="hljs-property">done</span> = <span class="hljs-literal">false</span>; 6721cb0ef41Sopenharmony_ci<span class="hljs-keyword">const</span> b = <span class="hljs-built_in">require</span>(<span class="hljs-string">'./b.js'</span>); 6731cb0ef41Sopenharmony_ci<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-string">'in a, b.done = %j'</span>, b.<span class="hljs-property">done</span>); 6741cb0ef41Sopenharmony_ci<span class="hljs-built_in">exports</span>.<span class="hljs-property">done</span> = <span class="hljs-literal">true</span>; 6751cb0ef41Sopenharmony_ci<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-string">'a done'</span>);</code> <button class="copy-button">copy</button></pre> 6761cb0ef41Sopenharmony_ci<p><code>b.js</code>:</p> 6771cb0ef41Sopenharmony_ci<pre><code class="language-js"><span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-string">'b starting'</span>); 6781cb0ef41Sopenharmony_ci<span class="hljs-built_in">exports</span>.<span class="hljs-property">done</span> = <span class="hljs-literal">false</span>; 6791cb0ef41Sopenharmony_ci<span class="hljs-keyword">const</span> a = <span class="hljs-built_in">require</span>(<span class="hljs-string">'./a.js'</span>); 6801cb0ef41Sopenharmony_ci<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-string">'in b, a.done = %j'</span>, a.<span class="hljs-property">done</span>); 6811cb0ef41Sopenharmony_ci<span class="hljs-built_in">exports</span>.<span class="hljs-property">done</span> = <span class="hljs-literal">true</span>; 6821cb0ef41Sopenharmony_ci<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-string">'b done'</span>);</code> <button class="copy-button">copy</button></pre> 6831cb0ef41Sopenharmony_ci<p><code>main.js</code>:</p> 6841cb0ef41Sopenharmony_ci<pre><code class="language-js"><span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-string">'main starting'</span>); 6851cb0ef41Sopenharmony_ci<span class="hljs-keyword">const</span> a = <span class="hljs-built_in">require</span>(<span class="hljs-string">'./a.js'</span>); 6861cb0ef41Sopenharmony_ci<span class="hljs-keyword">const</span> b = <span class="hljs-built_in">require</span>(<span class="hljs-string">'./b.js'</span>); 6871cb0ef41Sopenharmony_ci<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-string">'in main, a.done = %j, b.done = %j'</span>, a.<span class="hljs-property">done</span>, b.<span class="hljs-property">done</span>);</code> <button class="copy-button">copy</button></pre> 6881cb0ef41Sopenharmony_ci<p>When <code>main.js</code> loads <code>a.js</code>, then <code>a.js</code> in turn loads <code>b.js</code>. At that 6891cb0ef41Sopenharmony_cipoint, <code>b.js</code> tries to load <code>a.js</code>. In order to prevent an infinite 6901cb0ef41Sopenharmony_ciloop, an <strong>unfinished copy</strong> of the <code>a.js</code> exports object is returned to the 6911cb0ef41Sopenharmony_ci<code>b.js</code> module. <code>b.js</code> then finishes loading, and its <code>exports</code> object is 6921cb0ef41Sopenharmony_ciprovided to the <code>a.js</code> module.</p> 6931cb0ef41Sopenharmony_ci<p>By the time <code>main.js</code> has loaded both modules, they're both finished. 6941cb0ef41Sopenharmony_ciThe output of this program would thus be:</p> 6951cb0ef41Sopenharmony_ci<pre><code class="language-console"><span class="hljs-meta prompt_">$ </span><span class="language-bash">node main.js</span> 6961cb0ef41Sopenharmony_cimain starting 6971cb0ef41Sopenharmony_cia starting 6981cb0ef41Sopenharmony_cib starting 6991cb0ef41Sopenharmony_ciin b, a.done = false 7001cb0ef41Sopenharmony_cib done 7011cb0ef41Sopenharmony_ciin a, b.done = true 7021cb0ef41Sopenharmony_cia done 7031cb0ef41Sopenharmony_ciin main, a.done = true, b.done = true</code> <button class="copy-button">copy</button></pre> 7041cb0ef41Sopenharmony_ci<p>Careful planning is required to allow cyclic module dependencies to work 7051cb0ef41Sopenharmony_cicorrectly within an application.</p> 7061cb0ef41Sopenharmony_ci</section><section><h3>File modules<span><a class="mark" href="#file-modules" id="file-modules">#</a></span><a aria-hidden="true" class="legacy" id="modules_file_modules"></a></h3> 7071cb0ef41Sopenharmony_ci 7081cb0ef41Sopenharmony_ci<p>If the exact filename is not found, then Node.js will attempt to load the 7091cb0ef41Sopenharmony_cirequired filename with the added extensions: <code>.js</code>, <code>.json</code>, and finally 7101cb0ef41Sopenharmony_ci<code>.node</code>. When loading a file that has a different extension (e.g. <code>.cjs</code>), its 7111cb0ef41Sopenharmony_cifull name must be passed to <code>require()</code>, including its file extension (e.g. 7121cb0ef41Sopenharmony_ci<code>require('./file.cjs')</code>).</p> 7131cb0ef41Sopenharmony_ci<p><code>.json</code> files are parsed as JSON text files, <code>.node</code> files are interpreted as 7141cb0ef41Sopenharmony_cicompiled addon modules loaded with <code>process.dlopen()</code>. Files using any other 7151cb0ef41Sopenharmony_ciextension (or no extension at all) are parsed as JavaScript text files. Refer to 7161cb0ef41Sopenharmony_cithe <a href="packages.html#determining-module-system">Determining module system</a> section to understand what parse goal will be 7171cb0ef41Sopenharmony_ciused.</p> 7181cb0ef41Sopenharmony_ci<p>A required module prefixed with <code>'/'</code> is an absolute path to the file. For 7191cb0ef41Sopenharmony_ciexample, <code>require('/home/marco/foo.js')</code> will load the file at 7201cb0ef41Sopenharmony_ci<code>/home/marco/foo.js</code>.</p> 7211cb0ef41Sopenharmony_ci<p>A required module prefixed with <code>'./'</code> is relative to the file calling 7221cb0ef41Sopenharmony_ci<code>require()</code>. That is, <code>circle.js</code> must be in the same directory as <code>foo.js</code> for 7231cb0ef41Sopenharmony_ci<code>require('./circle')</code> to find it.</p> 7241cb0ef41Sopenharmony_ci<p>Without a leading <code>'/'</code>, <code>'./'</code>, or <code>'../'</code> to indicate a file, the module must 7251cb0ef41Sopenharmony_cieither be a core module or is loaded from a <code>node_modules</code> folder.</p> 7261cb0ef41Sopenharmony_ci<p>If the given path does not exist, <code>require()</code> will throw a 7271cb0ef41Sopenharmony_ci<a href="errors.html#module_not_found"><code>MODULE_NOT_FOUND</code></a> error.</p> 7281cb0ef41Sopenharmony_ci</section><section><h3>Folders as modules<span><a class="mark" href="#folders-as-modules" id="folders-as-modules">#</a></span><a aria-hidden="true" class="legacy" id="modules_folders_as_modules"></a></h3> 7291cb0ef41Sopenharmony_ci 7301cb0ef41Sopenharmony_ci<p></p><div class="api_stability api_stability_3"><a href="documentation.html#stability-index">Stability: 3</a> - Legacy: Use <a href="packages.html#subpath-exports">subpath exports</a> or <a href="packages.html#subpath-imports">subpath imports</a> instead.</div><p></p> 7311cb0ef41Sopenharmony_ci<p>There are three ways in which a folder may be passed to <code>require()</code> as 7321cb0ef41Sopenharmony_cian argument.</p> 7331cb0ef41Sopenharmony_ci<p>The first is to create a <a href="packages.html#nodejs-packagejson-field-definitions"><code>package.json</code></a> file in the root of the folder, 7341cb0ef41Sopenharmony_ciwhich specifies a <code>main</code> module. An example <a href="packages.html#nodejs-packagejson-field-definitions"><code>package.json</code></a> file might 7351cb0ef41Sopenharmony_cilook like this:</p> 7361cb0ef41Sopenharmony_ci<pre><code class="language-json"><span class="hljs-punctuation">{</span> <span class="hljs-attr">"name"</span> <span class="hljs-punctuation">:</span> <span class="hljs-string">"some-library"</span><span class="hljs-punctuation">,</span> 7371cb0ef41Sopenharmony_ci <span class="hljs-attr">"main"</span> <span class="hljs-punctuation">:</span> <span class="hljs-string">"./lib/some-library.js"</span> <span class="hljs-punctuation">}</span></code> <button class="copy-button">copy</button></pre> 7381cb0ef41Sopenharmony_ci<p>If this was in a folder at <code>./some-library</code>, then 7391cb0ef41Sopenharmony_ci<code>require('./some-library')</code> would attempt to load 7401cb0ef41Sopenharmony_ci<code>./some-library/lib/some-library.js</code>.</p> 7411cb0ef41Sopenharmony_ci<p>If there is no <a href="packages.html#nodejs-packagejson-field-definitions"><code>package.json</code></a> file present in the directory, or if the 7421cb0ef41Sopenharmony_ci<a href="packages.html#main"><code>"main"</code></a> entry is missing or cannot be resolved, then Node.js 7431cb0ef41Sopenharmony_ciwill attempt to load an <code>index.js</code> or <code>index.node</code> file out of that 7441cb0ef41Sopenharmony_cidirectory. For example, if there was no <a href="packages.html#nodejs-packagejson-field-definitions"><code>package.json</code></a> file in the previous 7451cb0ef41Sopenharmony_ciexample, then <code>require('./some-library')</code> would attempt to load:</p> 7461cb0ef41Sopenharmony_ci<ul> 7471cb0ef41Sopenharmony_ci<li><code>./some-library/index.js</code></li> 7481cb0ef41Sopenharmony_ci<li><code>./some-library/index.node</code></li> 7491cb0ef41Sopenharmony_ci</ul> 7501cb0ef41Sopenharmony_ci<p>If these attempts fail, then Node.js will report the entire module as missing 7511cb0ef41Sopenharmony_ciwith the default error:</p> 7521cb0ef41Sopenharmony_ci<pre><code class="language-console">Error: Cannot find module 'some-library'</code> <button class="copy-button">copy</button></pre> 7531cb0ef41Sopenharmony_ci<p>In all three above cases, an <code>import('./some-library')</code> call would result in a 7541cb0ef41Sopenharmony_ci<a href="errors.html#err_unsupported_dir_import"><code>ERR_UNSUPPORTED_DIR_IMPORT</code></a> error. Using package <a href="packages.html#subpath-exports">subpath exports</a> or 7551cb0ef41Sopenharmony_ci<a href="packages.html#subpath-imports">subpath imports</a> can provide the same containment organization benefits as 7561cb0ef41Sopenharmony_cifolders as modules, and work for both <code>require</code> and <code>import</code>.</p> 7571cb0ef41Sopenharmony_ci</section><section><h3>Loading from <code>node_modules</code> folders<span><a class="mark" href="#loading-from-node_modules-folders" id="loading-from-node_modules-folders">#</a></span><a aria-hidden="true" class="legacy" id="modules_loading_from_node_modules_folders"></a></h3> 7581cb0ef41Sopenharmony_ci 7591cb0ef41Sopenharmony_ci<p>If the module identifier passed to <code>require()</code> is not a 7601cb0ef41Sopenharmony_ci<a href="#core-modules">core</a> module, and does not begin with <code>'/'</code>, <code>'../'</code>, or 7611cb0ef41Sopenharmony_ci<code>'./'</code>, then Node.js starts at the directory of the current module, and 7621cb0ef41Sopenharmony_ciadds <code>/node_modules</code>, and attempts to load the module from that location. 7631cb0ef41Sopenharmony_ciNode.js will not append <code>node_modules</code> to a path already ending in 7641cb0ef41Sopenharmony_ci<code>node_modules</code>.</p> 7651cb0ef41Sopenharmony_ci<p>If it is not found there, then it moves to the parent directory, and so 7661cb0ef41Sopenharmony_cion, until the root of the file system is reached.</p> 7671cb0ef41Sopenharmony_ci<p>For example, if the file at <code>'/home/ry/projects/foo.js'</code> called 7681cb0ef41Sopenharmony_ci<code>require('bar.js')</code>, then Node.js would look in the following locations, in 7691cb0ef41Sopenharmony_cithis order:</p> 7701cb0ef41Sopenharmony_ci<ul> 7711cb0ef41Sopenharmony_ci<li><code>/home/ry/projects/node_modules/bar.js</code></li> 7721cb0ef41Sopenharmony_ci<li><code>/home/ry/node_modules/bar.js</code></li> 7731cb0ef41Sopenharmony_ci<li><code>/home/node_modules/bar.js</code></li> 7741cb0ef41Sopenharmony_ci<li><code>/node_modules/bar.js</code></li> 7751cb0ef41Sopenharmony_ci</ul> 7761cb0ef41Sopenharmony_ci<p>This allows programs to localize their dependencies, so that they do not 7771cb0ef41Sopenharmony_ciclash.</p> 7781cb0ef41Sopenharmony_ci<p>It is possible to require specific files or sub modules distributed with a 7791cb0ef41Sopenharmony_cimodule by including a path suffix after the module name. For instance 7801cb0ef41Sopenharmony_ci<code>require('example-module/path/to/file')</code> would resolve <code>path/to/file</code> 7811cb0ef41Sopenharmony_cirelative to where <code>example-module</code> is located. The suffixed path follows the 7821cb0ef41Sopenharmony_cisame module resolution semantics.</p> 7831cb0ef41Sopenharmony_ci</section><section><h3>Loading from the global folders<span><a class="mark" href="#loading-from-the-global-folders" id="loading-from-the-global-folders">#</a></span><a aria-hidden="true" class="legacy" id="modules_loading_from_the_global_folders"></a></h3> 7841cb0ef41Sopenharmony_ci 7851cb0ef41Sopenharmony_ci<p>If the <code>NODE_PATH</code> environment variable is set to a colon-delimited list 7861cb0ef41Sopenharmony_ciof absolute paths, then Node.js will search those paths for modules if they 7871cb0ef41Sopenharmony_ciare not found elsewhere.</p> 7881cb0ef41Sopenharmony_ci<p>On Windows, <code>NODE_PATH</code> is delimited by semicolons (<code>;</code>) instead of colons.</p> 7891cb0ef41Sopenharmony_ci<p><code>NODE_PATH</code> was originally created to support loading modules from 7901cb0ef41Sopenharmony_civarying paths before the current <a href="#all-together">module resolution</a> algorithm was defined.</p> 7911cb0ef41Sopenharmony_ci<p><code>NODE_PATH</code> is still supported, but is less necessary now that the Node.js 7921cb0ef41Sopenharmony_ciecosystem has settled on a convention for locating dependent modules. 7931cb0ef41Sopenharmony_ciSometimes deployments that rely on <code>NODE_PATH</code> show surprising behavior 7941cb0ef41Sopenharmony_ciwhen people are unaware that <code>NODE_PATH</code> must be set. Sometimes a 7951cb0ef41Sopenharmony_cimodule's dependencies change, causing a different version (or even a 7961cb0ef41Sopenharmony_cidifferent module) to be loaded as the <code>NODE_PATH</code> is searched.</p> 7971cb0ef41Sopenharmony_ci<p>Additionally, Node.js will search in the following list of GLOBAL_FOLDERS:</p> 7981cb0ef41Sopenharmony_ci<ul> 7991cb0ef41Sopenharmony_ci<li>1: <code>$HOME/.node_modules</code></li> 8001cb0ef41Sopenharmony_ci<li>2: <code>$HOME/.node_libraries</code></li> 8011cb0ef41Sopenharmony_ci<li>3: <code>$PREFIX/lib/node</code></li> 8021cb0ef41Sopenharmony_ci</ul> 8031cb0ef41Sopenharmony_ci<p>Where <code>$HOME</code> is the user's home directory, and <code>$PREFIX</code> is the Node.js 8041cb0ef41Sopenharmony_ciconfigured <code>node_prefix</code>.</p> 8051cb0ef41Sopenharmony_ci<p>These are mostly for historic reasons.</p> 8061cb0ef41Sopenharmony_ci<p>It is strongly encouraged to place dependencies in the local <code>node_modules</code> 8071cb0ef41Sopenharmony_cifolder. These will be loaded faster, and more reliably.</p> 8081cb0ef41Sopenharmony_ci</section><section><h3>The module wrapper<span><a class="mark" href="#the-module-wrapper" id="the-module-wrapper">#</a></span><a aria-hidden="true" class="legacy" id="modules_the_module_wrapper"></a></h3> 8091cb0ef41Sopenharmony_ci 8101cb0ef41Sopenharmony_ci<p>Before a module's code is executed, Node.js will wrap it with a function 8111cb0ef41Sopenharmony_ciwrapper that looks like the following:</p> 8121cb0ef41Sopenharmony_ci<pre><code class="language-js">(<span class="hljs-keyword">function</span>(<span class="hljs-params"><span class="hljs-built_in">exports</span>, <span class="hljs-built_in">require</span>, <span class="hljs-variable language_">module</span>, __filename, __dirname</span>) { 8131cb0ef41Sopenharmony_ci<span class="hljs-comment">// Module code actually lives in here</span> 8141cb0ef41Sopenharmony_ci});</code> <button class="copy-button">copy</button></pre> 8151cb0ef41Sopenharmony_ci<p>By doing this, Node.js achieves a few things:</p> 8161cb0ef41Sopenharmony_ci<ul> 8171cb0ef41Sopenharmony_ci<li>It keeps top-level variables (defined with <code>var</code>, <code>const</code>, or <code>let</code>) scoped to 8181cb0ef41Sopenharmony_cithe module rather than the global object.</li> 8191cb0ef41Sopenharmony_ci<li>It helps to provide some global-looking variables that are actually specific 8201cb0ef41Sopenharmony_cito the module, such as: 8211cb0ef41Sopenharmony_ci<ul> 8221cb0ef41Sopenharmony_ci<li>The <code>module</code> and <code>exports</code> objects that the implementor can use to export 8231cb0ef41Sopenharmony_civalues from the module.</li> 8241cb0ef41Sopenharmony_ci<li>The convenience variables <code>__filename</code> and <code>__dirname</code>, containing the 8251cb0ef41Sopenharmony_cimodule's absolute filename and directory path.</li> 8261cb0ef41Sopenharmony_ci</ul> 8271cb0ef41Sopenharmony_ci</li> 8281cb0ef41Sopenharmony_ci</ul> 8291cb0ef41Sopenharmony_ci</section><section><h3>The module scope<span><a class="mark" href="#the-module-scope" id="the-module-scope">#</a></span><a aria-hidden="true" class="legacy" id="modules_the_module_scope"></a></h3> 8301cb0ef41Sopenharmony_ci<h4><code>__dirname</code><span><a class="mark" href="#__dirname" id="__dirname">#</a></span><a aria-hidden="true" class="legacy" id="modules_dirname"></a></h4> 8311cb0ef41Sopenharmony_ci<div class="api_metadata"> 8321cb0ef41Sopenharmony_ci<span>Added in: v0.1.27</span> 8331cb0ef41Sopenharmony_ci</div> 8341cb0ef41Sopenharmony_ci 8351cb0ef41Sopenharmony_ci<ul> 8361cb0ef41Sopenharmony_ci<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a></li> 8371cb0ef41Sopenharmony_ci</ul> 8381cb0ef41Sopenharmony_ci<p>The directory name of the current module. This is the same as the 8391cb0ef41Sopenharmony_ci<a href="path.html#pathdirnamepath"><code>path.dirname()</code></a> of the <a href="#__filename"><code>__filename</code></a>.</p> 8401cb0ef41Sopenharmony_ci<p>Example: running <code>node example.js</code> from <code>/Users/mjr</code></p> 8411cb0ef41Sopenharmony_ci<pre><code class="language-js"><span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(__dirname); 8421cb0ef41Sopenharmony_ci<span class="hljs-comment">// Prints: /Users/mjr</span> 8431cb0ef41Sopenharmony_ci<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(path.<span class="hljs-title function_">dirname</span>(__filename)); 8441cb0ef41Sopenharmony_ci<span class="hljs-comment">// Prints: /Users/mjr</span></code> <button class="copy-button">copy</button></pre> 8451cb0ef41Sopenharmony_ci<h4><code>__filename</code><span><a class="mark" href="#__filename" id="__filename">#</a></span><a aria-hidden="true" class="legacy" id="modules_filename"></a></h4> 8461cb0ef41Sopenharmony_ci<div class="api_metadata"> 8471cb0ef41Sopenharmony_ci<span>Added in: v0.0.1</span> 8481cb0ef41Sopenharmony_ci</div> 8491cb0ef41Sopenharmony_ci 8501cb0ef41Sopenharmony_ci<ul> 8511cb0ef41Sopenharmony_ci<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a></li> 8521cb0ef41Sopenharmony_ci</ul> 8531cb0ef41Sopenharmony_ci<p>The file name of the current module. This is the current module file's absolute 8541cb0ef41Sopenharmony_cipath with symlinks resolved.</p> 8551cb0ef41Sopenharmony_ci<p>For a main program this is not necessarily the same as the file name used in the 8561cb0ef41Sopenharmony_cicommand line.</p> 8571cb0ef41Sopenharmony_ci<p>See <a href="#__dirname"><code>__dirname</code></a> for the directory name of the current module.</p> 8581cb0ef41Sopenharmony_ci<p>Examples:</p> 8591cb0ef41Sopenharmony_ci<p>Running <code>node example.js</code> from <code>/Users/mjr</code></p> 8601cb0ef41Sopenharmony_ci<pre><code class="language-js"><span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(__filename); 8611cb0ef41Sopenharmony_ci<span class="hljs-comment">// Prints: /Users/mjr/example.js</span> 8621cb0ef41Sopenharmony_ci<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(__dirname); 8631cb0ef41Sopenharmony_ci<span class="hljs-comment">// Prints: /Users/mjr</span></code> <button class="copy-button">copy</button></pre> 8641cb0ef41Sopenharmony_ci<p>Given two modules: <code>a</code> and <code>b</code>, where <code>b</code> is a dependency of 8651cb0ef41Sopenharmony_ci<code>a</code> and there is a directory structure of:</p> 8661cb0ef41Sopenharmony_ci<ul> 8671cb0ef41Sopenharmony_ci<li><code>/Users/mjr/app/a.js</code></li> 8681cb0ef41Sopenharmony_ci<li><code>/Users/mjr/app/node_modules/b/b.js</code></li> 8691cb0ef41Sopenharmony_ci</ul> 8701cb0ef41Sopenharmony_ci<p>References to <code>__filename</code> within <code>b.js</code> will return 8711cb0ef41Sopenharmony_ci<code>/Users/mjr/app/node_modules/b/b.js</code> while references to <code>__filename</code> within 8721cb0ef41Sopenharmony_ci<code>a.js</code> will return <code>/Users/mjr/app/a.js</code>.</p> 8731cb0ef41Sopenharmony_ci<h4><code>exports</code><span><a class="mark" href="#exports" id="exports">#</a></span><a aria-hidden="true" class="legacy" id="modules_exports"></a></h4> 8741cb0ef41Sopenharmony_ci<div class="api_metadata"> 8751cb0ef41Sopenharmony_ci<span>Added in: v0.1.12</span> 8761cb0ef41Sopenharmony_ci</div> 8771cb0ef41Sopenharmony_ci 8781cb0ef41Sopenharmony_ci<ul> 8791cb0ef41Sopenharmony_ci<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a></li> 8801cb0ef41Sopenharmony_ci</ul> 8811cb0ef41Sopenharmony_ci<p>A reference to the <code>module.exports</code> that is shorter to type. 8821cb0ef41Sopenharmony_ciSee the section about the <a href="#exports-shortcut">exports shortcut</a> for details on when to use 8831cb0ef41Sopenharmony_ci<code>exports</code> and when to use <code>module.exports</code>.</p> 8841cb0ef41Sopenharmony_ci<h4><code>module</code><span><a class="mark" href="#module" id="module">#</a></span><a aria-hidden="true" class="legacy" id="modules_module"></a></h4> 8851cb0ef41Sopenharmony_ci<div class="api_metadata"> 8861cb0ef41Sopenharmony_ci<span>Added in: v0.1.16</span> 8871cb0ef41Sopenharmony_ci</div> 8881cb0ef41Sopenharmony_ci 8891cb0ef41Sopenharmony_ci<ul> 8901cb0ef41Sopenharmony_ci<li><a href="modules.html#the-module-object" class="type"><module></a></li> 8911cb0ef41Sopenharmony_ci</ul> 8921cb0ef41Sopenharmony_ci<p>A reference to the current module, see the section about the 8931cb0ef41Sopenharmony_ci<a href="#the-module-object"><code>module</code> object</a>. In particular, <code>module.exports</code> is used for defining what 8941cb0ef41Sopenharmony_cia module exports and makes available through <code>require()</code>.</p> 8951cb0ef41Sopenharmony_ci<h4><code>require(id)</code><span><a class="mark" href="#requireid" id="requireid">#</a></span><a aria-hidden="true" class="legacy" id="modules_require_id"></a></h4> 8961cb0ef41Sopenharmony_ci<div class="api_metadata"> 8971cb0ef41Sopenharmony_ci<span>Added in: v0.1.13</span> 8981cb0ef41Sopenharmony_ci</div> 8991cb0ef41Sopenharmony_ci 9001cb0ef41Sopenharmony_ci<ul> 9011cb0ef41Sopenharmony_ci<li><code>id</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> module name or path</li> 9021cb0ef41Sopenharmony_ci<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type"><any></a> exported module content</li> 9031cb0ef41Sopenharmony_ci</ul> 9041cb0ef41Sopenharmony_ci<p>Used to import modules, <code>JSON</code>, and local files. Modules can be imported 9051cb0ef41Sopenharmony_cifrom <code>node_modules</code>. Local modules and JSON files can be imported using 9061cb0ef41Sopenharmony_cia relative path (e.g. <code>./</code>, <code>./foo</code>, <code>./bar/baz</code>, <code>../foo</code>) that will be 9071cb0ef41Sopenharmony_ciresolved against the directory named by <a href="#__dirname"><code>__dirname</code></a> (if defined) or 9081cb0ef41Sopenharmony_cithe current working directory. The relative paths of POSIX style are resolved 9091cb0ef41Sopenharmony_ciin an OS independent fashion, meaning that the examples above will work on 9101cb0ef41Sopenharmony_ciWindows in the same way they would on Unix systems.</p> 9111cb0ef41Sopenharmony_ci<pre><code class="language-js"><span class="hljs-comment">// Importing a local module with a path relative to the `__dirname` or current</span> 9121cb0ef41Sopenharmony_ci<span class="hljs-comment">// working directory. (On Windows, this would resolve to .\path\myLocalModule.)</span> 9131cb0ef41Sopenharmony_ci<span class="hljs-keyword">const</span> myLocalModule = <span class="hljs-built_in">require</span>(<span class="hljs-string">'./path/myLocalModule'</span>); 9141cb0ef41Sopenharmony_ci 9151cb0ef41Sopenharmony_ci<span class="hljs-comment">// Importing a JSON file:</span> 9161cb0ef41Sopenharmony_ci<span class="hljs-keyword">const</span> jsonData = <span class="hljs-built_in">require</span>(<span class="hljs-string">'./path/filename.json'</span>); 9171cb0ef41Sopenharmony_ci 9181cb0ef41Sopenharmony_ci<span class="hljs-comment">// Importing a module from node_modules or Node.js built-in module:</span> 9191cb0ef41Sopenharmony_ci<span class="hljs-keyword">const</span> crypto = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:crypto'</span>);</code> <button class="copy-button">copy</button></pre> 9201cb0ef41Sopenharmony_ci<h5><code>require.cache</code><span><a class="mark" href="#requirecache" id="requirecache">#</a></span><a aria-hidden="true" class="legacy" id="modules_require_cache"></a></h5> 9211cb0ef41Sopenharmony_ci<div class="api_metadata"> 9221cb0ef41Sopenharmony_ci<span>Added in: v0.3.0</span> 9231cb0ef41Sopenharmony_ci</div> 9241cb0ef41Sopenharmony_ci<ul> 9251cb0ef41Sopenharmony_ci<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a></li> 9261cb0ef41Sopenharmony_ci</ul> 9271cb0ef41Sopenharmony_ci<p>Modules are cached in this object when they are required. By deleting a key 9281cb0ef41Sopenharmony_civalue from this object, the next <code>require</code> will reload the module. 9291cb0ef41Sopenharmony_ciThis does not apply to <a href="addons.html">native addons</a>, for which reloading will result in an 9301cb0ef41Sopenharmony_cierror.</p> 9311cb0ef41Sopenharmony_ci<p>Adding or replacing entries is also possible. This cache is checked before 9321cb0ef41Sopenharmony_cibuilt-in modules and if a name matching a built-in module is added to the cache, 9331cb0ef41Sopenharmony_cionly <code>node:</code>-prefixed require calls are going to receive the built-in module. 9341cb0ef41Sopenharmony_ciUse with care!</p> 9351cb0ef41Sopenharmony_ci<!-- eslint-disable node-core/no-duplicate-requires --> 9361cb0ef41Sopenharmony_ci<pre><code class="language-js"><span class="hljs-keyword">const</span> assert = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:assert'</span>); 9371cb0ef41Sopenharmony_ci<span class="hljs-keyword">const</span> realFs = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:fs'</span>); 9381cb0ef41Sopenharmony_ci 9391cb0ef41Sopenharmony_ci<span class="hljs-keyword">const</span> fakeFs = {}; 9401cb0ef41Sopenharmony_ci<span class="hljs-built_in">require</span>.<span class="hljs-property">cache</span>.<span class="hljs-property">fs</span> = { <span class="hljs-attr">exports</span>: fakeFs }; 9411cb0ef41Sopenharmony_ci 9421cb0ef41Sopenharmony_ciassert.<span class="hljs-title function_">strictEqual</span>(<span class="hljs-built_in">require</span>(<span class="hljs-string">'fs'</span>), fakeFs); 9431cb0ef41Sopenharmony_ciassert.<span class="hljs-title function_">strictEqual</span>(<span class="hljs-built_in">require</span>(<span class="hljs-string">'node:fs'</span>), realFs);</code> <button class="copy-button">copy</button></pre> 9441cb0ef41Sopenharmony_ci<h5><code>require.extensions</code><span><a class="mark" href="#requireextensions" id="requireextensions">#</a></span><a aria-hidden="true" class="legacy" id="modules_require_extensions"></a></h5> 9451cb0ef41Sopenharmony_ci<div class="api_metadata"> 9461cb0ef41Sopenharmony_ci<span>Added in: v0.3.0</span><span>Deprecated since: v0.10.6</span> 9471cb0ef41Sopenharmony_ci</div> 9481cb0ef41Sopenharmony_ci<p></p><div class="api_stability api_stability_0"><a href="documentation.html#stability-index">Stability: 0</a> - Deprecated</div><p></p> 9491cb0ef41Sopenharmony_ci<ul> 9501cb0ef41Sopenharmony_ci<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a></li> 9511cb0ef41Sopenharmony_ci</ul> 9521cb0ef41Sopenharmony_ci<p>Instruct <code>require</code> on how to handle certain file extensions.</p> 9531cb0ef41Sopenharmony_ci<p>Process files with the extension <code>.sjs</code> as <code>.js</code>:</p> 9541cb0ef41Sopenharmony_ci<pre><code class="language-js"><span class="hljs-built_in">require</span>.<span class="hljs-property">extensions</span>[<span class="hljs-string">'.sjs'</span>] = <span class="hljs-built_in">require</span>.<span class="hljs-property">extensions</span>[<span class="hljs-string">'.js'</span>];</code> <button class="copy-button">copy</button></pre> 9551cb0ef41Sopenharmony_ci<p><strong>Deprecated.</strong> In the past, this list has been used to load non-JavaScript 9561cb0ef41Sopenharmony_cimodules into Node.js by compiling them on-demand. However, in practice, there 9571cb0ef41Sopenharmony_ciare much better ways to do this, such as loading modules via some other Node.js 9581cb0ef41Sopenharmony_ciprogram, or compiling them to JavaScript ahead of time.</p> 9591cb0ef41Sopenharmony_ci<p>Avoid using <code>require.extensions</code>. Use could cause subtle bugs and resolving the 9601cb0ef41Sopenharmony_ciextensions gets slower with each registered extension.</p> 9611cb0ef41Sopenharmony_ci<h5><code>require.main</code><span><a class="mark" href="#requiremain" id="requiremain">#</a></span><a aria-hidden="true" class="legacy" id="modules_require_main"></a></h5> 9621cb0ef41Sopenharmony_ci<div class="api_metadata"> 9631cb0ef41Sopenharmony_ci<span>Added in: v0.1.17</span> 9641cb0ef41Sopenharmony_ci</div> 9651cb0ef41Sopenharmony_ci<ul> 9661cb0ef41Sopenharmony_ci<li><a href="modules.html#the-module-object" class="type"><module></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Undefined_type" class="type"><undefined></a></li> 9671cb0ef41Sopenharmony_ci</ul> 9681cb0ef41Sopenharmony_ci<p>The <code>Module</code> object representing the entry script loaded when the Node.js 9691cb0ef41Sopenharmony_ciprocess launched, or <code>undefined</code> if the entry point of the program is not a 9701cb0ef41Sopenharmony_ciCommonJS module. 9711cb0ef41Sopenharmony_ciSee <a href="#accessing-the-main-module">"Accessing the main module"</a>.</p> 9721cb0ef41Sopenharmony_ci<p>In <code>entry.js</code> script:</p> 9731cb0ef41Sopenharmony_ci<pre><code class="language-js"><span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-built_in">require</span>.<span class="hljs-property">main</span>);</code> <button class="copy-button">copy</button></pre> 9741cb0ef41Sopenharmony_ci<pre><code class="language-bash">node entry.js</code> <button class="copy-button">copy</button></pre> 9751cb0ef41Sopenharmony_ci<!-- eslint-skip --> 9761cb0ef41Sopenharmony_ci<pre><code class="language-js"><span class="hljs-title class_">Module</span> { 9771cb0ef41Sopenharmony_ci <span class="hljs-attr">id</span>: <span class="hljs-string">'.'</span>, 9781cb0ef41Sopenharmony_ci <span class="hljs-attr">path</span>: <span class="hljs-string">'/absolute/path/to'</span>, 9791cb0ef41Sopenharmony_ci <span class="hljs-attr">exports</span>: {}, 9801cb0ef41Sopenharmony_ci <span class="hljs-attr">filename</span>: <span class="hljs-string">'/absolute/path/to/entry.js'</span>, 9811cb0ef41Sopenharmony_ci <span class="hljs-attr">loaded</span>: <span class="hljs-literal">false</span>, 9821cb0ef41Sopenharmony_ci <span class="hljs-attr">children</span>: [], 9831cb0ef41Sopenharmony_ci <span class="hljs-attr">paths</span>: 9841cb0ef41Sopenharmony_ci [ <span class="hljs-string">'/absolute/path/to/node_modules'</span>, 9851cb0ef41Sopenharmony_ci <span class="hljs-string">'/absolute/path/node_modules'</span>, 9861cb0ef41Sopenharmony_ci <span class="hljs-string">'/absolute/node_modules'</span>, 9871cb0ef41Sopenharmony_ci <span class="hljs-string">'/node_modules'</span> ] }</code> <button class="copy-button">copy</button></pre> 9881cb0ef41Sopenharmony_ci<h5><code>require.resolve(request[, options])</code><span><a class="mark" href="#requireresolverequest-options" id="requireresolverequest-options">#</a></span><a aria-hidden="true" class="legacy" id="modules_require_resolve_request_options"></a></h5> 9891cb0ef41Sopenharmony_ci<div class="api_metadata"> 9901cb0ef41Sopenharmony_ci<details class="changelog"><summary>History</summary> 9911cb0ef41Sopenharmony_ci<table> 9921cb0ef41Sopenharmony_ci<tbody><tr><th>Version</th><th>Changes</th></tr> 9931cb0ef41Sopenharmony_ci<tr><td>v8.9.0</td> 9941cb0ef41Sopenharmony_ci<td><p>The <code>paths</code> option is now supported.</p></td></tr> 9951cb0ef41Sopenharmony_ci<tr><td>v0.3.0</td> 9961cb0ef41Sopenharmony_ci<td><p><span>Added in: v0.3.0</span></p></td></tr> 9971cb0ef41Sopenharmony_ci</tbody></table> 9981cb0ef41Sopenharmony_ci</details> 9991cb0ef41Sopenharmony_ci</div> 10001cb0ef41Sopenharmony_ci<ul> 10011cb0ef41Sopenharmony_ci<li><code>request</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> The module path to resolve.</li> 10021cb0ef41Sopenharmony_ci<li><code>options</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a> 10031cb0ef41Sopenharmony_ci<ul> 10041cb0ef41Sopenharmony_ci<li><code>paths</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string[]></a> Paths to resolve module location from. If present, these 10051cb0ef41Sopenharmony_cipaths are used instead of the default resolution paths, with the exception 10061cb0ef41Sopenharmony_ciof <a href="#loading-from-the-global-folders">GLOBAL_FOLDERS</a> like <code>$HOME/.node_modules</code>, which are 10071cb0ef41Sopenharmony_cialways included. Each of these paths is used as a starting point for 10081cb0ef41Sopenharmony_cithe module resolution algorithm, meaning that the <code>node_modules</code> hierarchy 10091cb0ef41Sopenharmony_ciis checked from this location.</li> 10101cb0ef41Sopenharmony_ci</ul> 10111cb0ef41Sopenharmony_ci</li> 10121cb0ef41Sopenharmony_ci<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a></li> 10131cb0ef41Sopenharmony_ci</ul> 10141cb0ef41Sopenharmony_ci<p>Use the internal <code>require()</code> machinery to look up the location of a module, 10151cb0ef41Sopenharmony_cibut rather than loading the module, just return the resolved filename.</p> 10161cb0ef41Sopenharmony_ci<p>If the module can not be found, a <code>MODULE_NOT_FOUND</code> error is thrown.</p> 10171cb0ef41Sopenharmony_ci<h6><code>require.resolve.paths(request)</code><span><a class="mark" href="#requireresolvepathsrequest" id="requireresolvepathsrequest">#</a></span><a aria-hidden="true" class="legacy" id="modules_require_resolve_paths_request"></a></h6> 10181cb0ef41Sopenharmony_ci<div class="api_metadata"> 10191cb0ef41Sopenharmony_ci<span>Added in: v8.9.0</span> 10201cb0ef41Sopenharmony_ci</div> 10211cb0ef41Sopenharmony_ci<ul> 10221cb0ef41Sopenharmony_ci<li><code>request</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> The module path whose lookup paths are being retrieved.</li> 10231cb0ef41Sopenharmony_ci<li>Returns: <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/Data_structures#Null_type" class="type"><null></a></li> 10241cb0ef41Sopenharmony_ci</ul> 10251cb0ef41Sopenharmony_ci<p>Returns an array containing the paths searched during resolution of <code>request</code> or 10261cb0ef41Sopenharmony_ci<code>null</code> if the <code>request</code> string references a core module, for example <code>http</code> or 10271cb0ef41Sopenharmony_ci<code>fs</code>.</p> 10281cb0ef41Sopenharmony_ci</section><section><h3>The <code>module</code> object<span><a class="mark" href="#the-module-object" id="the-module-object">#</a></span><a aria-hidden="true" class="legacy" id="modules_the_module_object"></a></h3> 10291cb0ef41Sopenharmony_ci<div class="api_metadata"> 10301cb0ef41Sopenharmony_ci<span>Added in: v0.1.16</span> 10311cb0ef41Sopenharmony_ci</div> 10321cb0ef41Sopenharmony_ci 10331cb0ef41Sopenharmony_ci 10341cb0ef41Sopenharmony_ci<ul> 10351cb0ef41Sopenharmony_ci<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a></li> 10361cb0ef41Sopenharmony_ci</ul> 10371cb0ef41Sopenharmony_ci<p>In each module, the <code>module</code> free variable is a reference to the object 10381cb0ef41Sopenharmony_cirepresenting the current module. For convenience, <code>module.exports</code> is 10391cb0ef41Sopenharmony_cialso accessible via the <code>exports</code> module-global. <code>module</code> is not actually 10401cb0ef41Sopenharmony_cia global but rather local to each module.</p> 10411cb0ef41Sopenharmony_ci<h4><code>module.children</code><span><a class="mark" href="#modulechildren" id="modulechildren">#</a></span><a aria-hidden="true" class="legacy" id="modules_module_children"></a></h4> 10421cb0ef41Sopenharmony_ci<div class="api_metadata"> 10431cb0ef41Sopenharmony_ci<span>Added in: v0.1.16</span> 10441cb0ef41Sopenharmony_ci</div> 10451cb0ef41Sopenharmony_ci<ul> 10461cb0ef41Sopenharmony_ci<li><a href="modules.html#the-module-object" class="type"><module[]></a></li> 10471cb0ef41Sopenharmony_ci</ul> 10481cb0ef41Sopenharmony_ci<p>The module objects required for the first time by this one.</p> 10491cb0ef41Sopenharmony_ci<h4><code>module.exports</code><span><a class="mark" href="#moduleexports" id="moduleexports">#</a></span><a aria-hidden="true" class="legacy" id="modules_module_exports"></a></h4> 10501cb0ef41Sopenharmony_ci<div class="api_metadata"> 10511cb0ef41Sopenharmony_ci<span>Added in: v0.1.16</span> 10521cb0ef41Sopenharmony_ci</div> 10531cb0ef41Sopenharmony_ci<ul> 10541cb0ef41Sopenharmony_ci<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a></li> 10551cb0ef41Sopenharmony_ci</ul> 10561cb0ef41Sopenharmony_ci<p>The <code>module.exports</code> object is created by the <code>Module</code> system. Sometimes this is 10571cb0ef41Sopenharmony_cinot acceptable; many want their module to be an instance of some class. To do 10581cb0ef41Sopenharmony_cithis, assign the desired export object to <code>module.exports</code>. Assigning 10591cb0ef41Sopenharmony_cithe desired object to <code>exports</code> will simply rebind the local <code>exports</code> variable, 10601cb0ef41Sopenharmony_ciwhich is probably not what is desired.</p> 10611cb0ef41Sopenharmony_ci<p>For example, suppose we were making a module called <code>a.js</code>:</p> 10621cb0ef41Sopenharmony_ci<pre><code class="language-js"><span class="hljs-keyword">const</span> <span class="hljs-title class_">EventEmitter</span> = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:events'</span>); 10631cb0ef41Sopenharmony_ci 10641cb0ef41Sopenharmony_ci<span class="hljs-variable language_">module</span>.<span class="hljs-property">exports</span> = <span class="hljs-keyword">new</span> <span class="hljs-title class_">EventEmitter</span>(); 10651cb0ef41Sopenharmony_ci 10661cb0ef41Sopenharmony_ci<span class="hljs-comment">// Do some work, and after some time emit</span> 10671cb0ef41Sopenharmony_ci<span class="hljs-comment">// the 'ready' event from the module itself.</span> 10681cb0ef41Sopenharmony_ci<span class="hljs-built_in">setTimeout</span>(<span class="hljs-function">() =></span> { 10691cb0ef41Sopenharmony_ci <span class="hljs-variable language_">module</span>.<span class="hljs-property">exports</span>.<span class="hljs-title function_">emit</span>(<span class="hljs-string">'ready'</span>); 10701cb0ef41Sopenharmony_ci}, <span class="hljs-number">1000</span>);</code> <button class="copy-button">copy</button></pre> 10711cb0ef41Sopenharmony_ci<p>Then in another file we could do:</p> 10721cb0ef41Sopenharmony_ci<pre><code class="language-js"><span class="hljs-keyword">const</span> a = <span class="hljs-built_in">require</span>(<span class="hljs-string">'./a'</span>); 10731cb0ef41Sopenharmony_cia.<span class="hljs-title function_">on</span>(<span class="hljs-string">'ready'</span>, <span class="hljs-function">() =></span> { 10741cb0ef41Sopenharmony_ci <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-string">'module "a" is ready'</span>); 10751cb0ef41Sopenharmony_ci});</code> <button class="copy-button">copy</button></pre> 10761cb0ef41Sopenharmony_ci<p>Assignment to <code>module.exports</code> must be done immediately. It cannot be 10771cb0ef41Sopenharmony_cidone in any callbacks. This does not work:</p> 10781cb0ef41Sopenharmony_ci<p><code>x.js</code>:</p> 10791cb0ef41Sopenharmony_ci<pre><code class="language-js"><span class="hljs-built_in">setTimeout</span>(<span class="hljs-function">() =></span> { 10801cb0ef41Sopenharmony_ci <span class="hljs-variable language_">module</span>.<span class="hljs-property">exports</span> = { <span class="hljs-attr">a</span>: <span class="hljs-string">'hello'</span> }; 10811cb0ef41Sopenharmony_ci}, <span class="hljs-number">0</span>);</code> <button class="copy-button">copy</button></pre> 10821cb0ef41Sopenharmony_ci<p><code>y.js</code>:</p> 10831cb0ef41Sopenharmony_ci<pre><code class="language-js"><span class="hljs-keyword">const</span> x = <span class="hljs-built_in">require</span>(<span class="hljs-string">'./x'</span>); 10841cb0ef41Sopenharmony_ci<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(x.<span class="hljs-property">a</span>);</code> <button class="copy-button">copy</button></pre> 10851cb0ef41Sopenharmony_ci<h5><code>exports</code> shortcut<span><a class="mark" href="#exports-shortcut" id="exports-shortcut">#</a></span><a aria-hidden="true" class="legacy" id="modules_exports_shortcut"></a></h5> 10861cb0ef41Sopenharmony_ci<div class="api_metadata"> 10871cb0ef41Sopenharmony_ci<span>Added in: v0.1.16</span> 10881cb0ef41Sopenharmony_ci</div> 10891cb0ef41Sopenharmony_ci<p>The <code>exports</code> variable is available within a module's file-level scope, and is 10901cb0ef41Sopenharmony_ciassigned the value of <code>module.exports</code> before the module is evaluated.</p> 10911cb0ef41Sopenharmony_ci<p>It allows a shortcut, so that <code>module.exports.f = ...</code> can be written more 10921cb0ef41Sopenharmony_cisuccinctly as <code>exports.f = ...</code>. However, be aware that like any variable, if a 10931cb0ef41Sopenharmony_cinew value is assigned to <code>exports</code>, it is no longer bound to <code>module.exports</code>:</p> 10941cb0ef41Sopenharmony_ci<pre><code class="language-js"><span class="hljs-variable language_">module</span>.<span class="hljs-property">exports</span>.<span class="hljs-property">hello</span> = <span class="hljs-literal">true</span>; <span class="hljs-comment">// Exported from require of module</span> 10951cb0ef41Sopenharmony_ci<span class="hljs-built_in">exports</span> = { <span class="hljs-attr">hello</span>: <span class="hljs-literal">false</span> }; <span class="hljs-comment">// Not exported, only available in the module</span></code> <button class="copy-button">copy</button></pre> 10961cb0ef41Sopenharmony_ci<p>When the <code>module.exports</code> property is being completely replaced by a new 10971cb0ef41Sopenharmony_ciobject, it is common to also reassign <code>exports</code>:</p> 10981cb0ef41Sopenharmony_ci<!-- eslint-disable func-name-matching --> 10991cb0ef41Sopenharmony_ci<pre><code class="language-js"><span class="hljs-variable language_">module</span>.<span class="hljs-property">exports</span> = <span class="hljs-built_in">exports</span> = <span class="hljs-keyword">function</span> <span class="hljs-title function_">Constructor</span>(<span class="hljs-params"></span>) { 11001cb0ef41Sopenharmony_ci <span class="hljs-comment">// ... etc.</span> 11011cb0ef41Sopenharmony_ci};</code> <button class="copy-button">copy</button></pre> 11021cb0ef41Sopenharmony_ci<p>To illustrate the behavior, imagine this hypothetical implementation of 11031cb0ef41Sopenharmony_ci<code>require()</code>, which is quite similar to what is actually done by <code>require()</code>:</p> 11041cb0ef41Sopenharmony_ci<pre><code class="language-js"><span class="hljs-keyword">function</span> <span class="hljs-title function_">require</span>(<span class="hljs-params"><span class="hljs-comment">/* ... */</span></span>) { 11051cb0ef41Sopenharmony_ci <span class="hljs-keyword">const</span> <span class="hljs-variable language_">module</span> = { <span class="hljs-attr">exports</span>: {} }; 11061cb0ef41Sopenharmony_ci (<span class="hljs-function">(<span class="hljs-params"><span class="hljs-variable language_">module</span>, <span class="hljs-built_in">exports</span></span>) =></span> { 11071cb0ef41Sopenharmony_ci <span class="hljs-comment">// Module code here. In this example, define a function.</span> 11081cb0ef41Sopenharmony_ci <span class="hljs-keyword">function</span> <span class="hljs-title function_">someFunc</span>(<span class="hljs-params"></span>) {} 11091cb0ef41Sopenharmony_ci <span class="hljs-built_in">exports</span> = someFunc; 11101cb0ef41Sopenharmony_ci <span class="hljs-comment">// At this point, exports is no longer a shortcut to module.exports, and</span> 11111cb0ef41Sopenharmony_ci <span class="hljs-comment">// this module will still export an empty default object.</span> 11121cb0ef41Sopenharmony_ci <span class="hljs-variable language_">module</span>.<span class="hljs-property">exports</span> = someFunc; 11131cb0ef41Sopenharmony_ci <span class="hljs-comment">// At this point, the module will now export someFunc, instead of the</span> 11141cb0ef41Sopenharmony_ci <span class="hljs-comment">// default object.</span> 11151cb0ef41Sopenharmony_ci })(<span class="hljs-variable language_">module</span>, <span class="hljs-variable language_">module</span>.<span class="hljs-property">exports</span>); 11161cb0ef41Sopenharmony_ci <span class="hljs-keyword">return</span> <span class="hljs-variable language_">module</span>.<span class="hljs-property">exports</span>; 11171cb0ef41Sopenharmony_ci}</code> <button class="copy-button">copy</button></pre> 11181cb0ef41Sopenharmony_ci<h4><code>module.filename</code><span><a class="mark" href="#modulefilename" id="modulefilename">#</a></span><a aria-hidden="true" class="legacy" id="modules_module_filename"></a></h4> 11191cb0ef41Sopenharmony_ci<div class="api_metadata"> 11201cb0ef41Sopenharmony_ci<span>Added in: v0.1.16</span> 11211cb0ef41Sopenharmony_ci</div> 11221cb0ef41Sopenharmony_ci<ul> 11231cb0ef41Sopenharmony_ci<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a></li> 11241cb0ef41Sopenharmony_ci</ul> 11251cb0ef41Sopenharmony_ci<p>The fully resolved filename of the module.</p> 11261cb0ef41Sopenharmony_ci<h4><code>module.id</code><span><a class="mark" href="#moduleid" id="moduleid">#</a></span><a aria-hidden="true" class="legacy" id="modules_module_id"></a></h4> 11271cb0ef41Sopenharmony_ci<div class="api_metadata"> 11281cb0ef41Sopenharmony_ci<span>Added in: v0.1.16</span> 11291cb0ef41Sopenharmony_ci</div> 11301cb0ef41Sopenharmony_ci<ul> 11311cb0ef41Sopenharmony_ci<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a></li> 11321cb0ef41Sopenharmony_ci</ul> 11331cb0ef41Sopenharmony_ci<p>The identifier for the module. Typically this is the fully resolved 11341cb0ef41Sopenharmony_cifilename.</p> 11351cb0ef41Sopenharmony_ci<h4><code>module.isPreloading</code><span><a class="mark" href="#moduleispreloading" id="moduleispreloading">#</a></span><a aria-hidden="true" class="legacy" id="modules_module_ispreloading"></a></h4> 11361cb0ef41Sopenharmony_ci<div class="api_metadata"> 11371cb0ef41Sopenharmony_ci<span>Added in: v15.4.0, v14.17.0</span> 11381cb0ef41Sopenharmony_ci</div> 11391cb0ef41Sopenharmony_ci<ul> 11401cb0ef41Sopenharmony_ci<li>Type: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type"><boolean></a> <code>true</code> if the module is running during the Node.js preload 11411cb0ef41Sopenharmony_ciphase.</li> 11421cb0ef41Sopenharmony_ci</ul> 11431cb0ef41Sopenharmony_ci<h4><code>module.loaded</code><span><a class="mark" href="#moduleloaded" id="moduleloaded">#</a></span><a aria-hidden="true" class="legacy" id="modules_module_loaded"></a></h4> 11441cb0ef41Sopenharmony_ci<div class="api_metadata"> 11451cb0ef41Sopenharmony_ci<span>Added in: v0.1.16</span> 11461cb0ef41Sopenharmony_ci</div> 11471cb0ef41Sopenharmony_ci<ul> 11481cb0ef41Sopenharmony_ci<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type"><boolean></a></li> 11491cb0ef41Sopenharmony_ci</ul> 11501cb0ef41Sopenharmony_ci<p>Whether or not the module is done loading, or is in the process of 11511cb0ef41Sopenharmony_ciloading.</p> 11521cb0ef41Sopenharmony_ci<h4><code>module.parent</code><span><a class="mark" href="#moduleparent" id="moduleparent">#</a></span><a aria-hidden="true" class="legacy" id="modules_module_parent"></a></h4> 11531cb0ef41Sopenharmony_ci<div class="api_metadata"> 11541cb0ef41Sopenharmony_ci<span>Added in: v0.1.16</span><span>Deprecated since: v14.6.0, v12.19.0</span> 11551cb0ef41Sopenharmony_ci</div> 11561cb0ef41Sopenharmony_ci<p></p><div class="api_stability api_stability_0"><a href="documentation.html#stability-index">Stability: 0</a> - Deprecated: Please use <a href="#requiremain"><code>require.main</code></a> and 11571cb0ef41Sopenharmony_ci<a href="#modulechildren"><code>module.children</code></a> instead.</div><p></p> 11581cb0ef41Sopenharmony_ci<ul> 11591cb0ef41Sopenharmony_ci<li><a href="modules.html#the-module-object" class="type"><module></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Null_type" class="type"><null></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Undefined_type" class="type"><undefined></a></li> 11601cb0ef41Sopenharmony_ci</ul> 11611cb0ef41Sopenharmony_ci<p>The module that first required this one, or <code>null</code> if the current module is the 11621cb0ef41Sopenharmony_cientry point of the current process, or <code>undefined</code> if the module was loaded by 11631cb0ef41Sopenharmony_cisomething that is not a CommonJS module (E.G.: REPL or <code>import</code>).</p> 11641cb0ef41Sopenharmony_ci<h4><code>module.path</code><span><a class="mark" href="#modulepath" id="modulepath">#</a></span><a aria-hidden="true" class="legacy" id="modules_module_path"></a></h4> 11651cb0ef41Sopenharmony_ci<div class="api_metadata"> 11661cb0ef41Sopenharmony_ci<span>Added in: v11.14.0</span> 11671cb0ef41Sopenharmony_ci</div> 11681cb0ef41Sopenharmony_ci<ul> 11691cb0ef41Sopenharmony_ci<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a></li> 11701cb0ef41Sopenharmony_ci</ul> 11711cb0ef41Sopenharmony_ci<p>The directory name of the module. This is usually the same as the 11721cb0ef41Sopenharmony_ci<a href="path.html#pathdirnamepath"><code>path.dirname()</code></a> of the <a href="#moduleid"><code>module.id</code></a>.</p> 11731cb0ef41Sopenharmony_ci<h4><code>module.paths</code><span><a class="mark" href="#modulepaths" id="modulepaths">#</a></span><a aria-hidden="true" class="legacy" id="modules_module_paths"></a></h4> 11741cb0ef41Sopenharmony_ci<div class="api_metadata"> 11751cb0ef41Sopenharmony_ci<span>Added in: v0.4.0</span> 11761cb0ef41Sopenharmony_ci</div> 11771cb0ef41Sopenharmony_ci<ul> 11781cb0ef41Sopenharmony_ci<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string[]></a></li> 11791cb0ef41Sopenharmony_ci</ul> 11801cb0ef41Sopenharmony_ci<p>The search paths for the module.</p> 11811cb0ef41Sopenharmony_ci<h4><code>module.require(id)</code><span><a class="mark" href="#modulerequireid" id="modulerequireid">#</a></span><a aria-hidden="true" class="legacy" id="modules_module_require_id"></a></h4> 11821cb0ef41Sopenharmony_ci<div class="api_metadata"> 11831cb0ef41Sopenharmony_ci<span>Added in: v0.5.1</span> 11841cb0ef41Sopenharmony_ci</div> 11851cb0ef41Sopenharmony_ci<ul> 11861cb0ef41Sopenharmony_ci<li><code>id</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a></li> 11871cb0ef41Sopenharmony_ci<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type"><any></a> exported module content</li> 11881cb0ef41Sopenharmony_ci</ul> 11891cb0ef41Sopenharmony_ci<p>The <code>module.require()</code> method provides a way to load a module as if 11901cb0ef41Sopenharmony_ci<code>require()</code> was called from the original module.</p> 11911cb0ef41Sopenharmony_ci<p>In order to do this, it is necessary to get a reference to the <code>module</code> object. 11921cb0ef41Sopenharmony_ciSince <code>require()</code> returns the <code>module.exports</code>, and the <code>module</code> is typically 11931cb0ef41Sopenharmony_ci<em>only</em> available within a specific module's code, it must be explicitly exported 11941cb0ef41Sopenharmony_ciin order to be used.</p> 11951cb0ef41Sopenharmony_ci</section><section><h3>The <code>Module</code> object<span><a class="mark" href="#the-module-object_1" id="the-module-object_1">#</a></span><a aria-hidden="true" class="legacy" id="modules_the_module_object_1"></a></h3> 11961cb0ef41Sopenharmony_ci<p>This section was moved to 11971cb0ef41Sopenharmony_ci<a href="module.html#the-module-object">Modules: <code>module</code> core module</a>.</p> 11981cb0ef41Sopenharmony_ci<!-- Anchors to make sure old links find a target --> 11991cb0ef41Sopenharmony_ci<ul> 12001cb0ef41Sopenharmony_ci<li><a id="modules_module_builtinmodules" href="module.html#modulebuiltinmodules"><code>module.builtinModules</code></a></li> 12011cb0ef41Sopenharmony_ci<li><a id="modules_module_createrequire_filename" href="module.html#modulecreaterequirefilename"><code>module.createRequire(filename)</code></a></li> 12021cb0ef41Sopenharmony_ci<li><a id="modules_module_syncbuiltinesmexports" href="module.html#modulesyncbuiltinesmexports"><code>module.syncBuiltinESMExports()</code></a></li> 12031cb0ef41Sopenharmony_ci</ul> 12041cb0ef41Sopenharmony_ci</section><section><h3>Source map v3 support<span><a class="mark" href="#source-map-v3-support" id="source-map-v3-support">#</a></span><a aria-hidden="true" class="legacy" id="modules_source_map_v3_support"></a></h3> 12051cb0ef41Sopenharmony_ci<p>This section was moved to 12061cb0ef41Sopenharmony_ci<a href="module.html#source-map-v3-support">Modules: <code>module</code> core module</a>.</p> 12071cb0ef41Sopenharmony_ci<!-- Anchors to make sure old links find a target --> 12081cb0ef41Sopenharmony_ci<ul> 12091cb0ef41Sopenharmony_ci<li><a id="modules_module_findsourcemap_path_error" href="module.html#modulefindsourcemappath"><code>module.findSourceMap(path)</code></a></li> 12101cb0ef41Sopenharmony_ci<li><a id="modules_class_module_sourcemap" href="module.html#class-modulesourcemap">Class: <code>module.SourceMap</code></a> 12111cb0ef41Sopenharmony_ci<ul> 12121cb0ef41Sopenharmony_ci<li><a id="modules_new_sourcemap_payload" href="module.html#new-sourcemappayload"><code>new SourceMap(payload)</code></a></li> 12131cb0ef41Sopenharmony_ci<li><a id="modules_sourcemap_payload" href="module.html#sourcemappayload"><code>sourceMap.payload</code></a></li> 12141cb0ef41Sopenharmony_ci<li><a id="modules_sourcemap_findentry_linenumber_columnnumber" href="module.html#sourcemapfindentrylinenumber-columnnumber"><code>sourceMap.findEntry(lineNumber, columnNumber)</code></a></li> 12151cb0ef41Sopenharmony_ci</ul> 12161cb0ef41Sopenharmony_ci</li> 12171cb0ef41Sopenharmony_ci</ul></section> 12181cb0ef41Sopenharmony_ci <!-- API END --> 12191cb0ef41Sopenharmony_ci </div> 12201cb0ef41Sopenharmony_ci </div> 12211cb0ef41Sopenharmony_ci </div> 12221cb0ef41Sopenharmony_ci</body> 12231cb0ef41Sopenharmony_ci</html> 1224