1<!DOCTYPE html> 2<html lang="en"> 3<head> 4 <meta charset="utf-8"> 5 <meta name="viewport" content="width=device-width"> 6 <meta name="nodejs.org:node-version" content="v18.20.1"> 7 <title>VM (executing JavaScript) | Node.js v18.20.1 Documentation</title> 8 <link rel="stylesheet" href="https://fonts.googleapis.com/css?family=Lato:400,700,400italic&display=fallback"> 9 <link rel="stylesheet" href="assets/style.css"> 10 <link rel="stylesheet" href="assets/hljs.css"> 11 <link rel="canonical" href="https://nodejs.org/api/vm.html"> 12 <script async defer src="assets/api.js" type="text/javascript"></script> 13 <style>@media(max-width:462px){.with-30-chars>.js-flavor-selector{float:none;margin:0 0 1em auto;}}@media(max-width:702px){.with-60-chars>.js-flavor-selector{float:none;margin:0 0 1em auto;}}</style> 14</head> 15<body class="alt apidoc" id="api-section-vm"> 16 <div id="content" class="clearfix"> 17 <div id="column2" class="interior"> 18 <div id="intro" class="interior"> 19 <a href="/" 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href="util.html" class="nav-util">Utilities</a></li> 82<li><a href="v8.html" class="nav-v8">V8</a></li> 83<li><a href="vm.html" class="nav-vm active">VM</a></li> 84<li><a href="wasi.html" class="nav-wasi">WASI</a></li> 85<li><a href="webcrypto.html" class="nav-webcrypto">Web Crypto API</a></li> 86<li><a href="webstreams.html" class="nav-webstreams">Web Streams API</a></li> 87<li><a href="worker_threads.html" class="nav-worker_threads">Worker threads</a></li> 88<li><a href="zlib.html" class="nav-zlib">Zlib</a></li> 89</ul> 90<hr class="line"> 91<ul> 92<li><a href="https://github.com/nodejs/node" class="nav-https-github-com-nodejs-node">Code repository and issue tracker</a></li> 93</ul> 94 </div> 95 96 <div id="column1" data-id="vm" class="interior"> 97 <header class="header"> 98 <div class="header-container"> 99 <h1>Node.js v18.20.1 documentation</h1> 100 <button class="theme-toggle-btn" id="theme-toggle-btn" title="Toggle dark mode/light mode" aria-label="Toggle dark mode/light mode" hidden> 101 <svg xmlns="http://www.w3.org/2000/svg" class="icon dark-icon" height="24" width="24"> 102 <path fill="none" d="M0 0h24v24H0z" /> 103 <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"/> 104 <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"/> 105 </svg> 106 <svg xmlns="http://www.w3.org/2000/svg" class="icon light-icon" height="24" width="24"> 107 <path d="M0 0h24v24H0z" fill="none" /> 108 <path d="M6.76 4.84l-1.8-1.79-1.41 1.41 1.79 1.79 1.42-1.41zM4 10.5H1v2h3v-2zm9-9.95h-2V3.5h2V.55zm7.45 3.91l-1.41-1.41-1.79 1.79 1.41 1.41 1.79-1.79zm-3.21 13.7l1.79 1.8 1.41-1.41-1.8-1.79-1.4 1.4zM20 10.5v2h3v-2h-3zm-8-5c-3.31 0-6 2.69-6 6s2.69 6 6 6 6-2.69 6-6-2.69-6-6-6zm-1 16.95h2V19.5h-2v2.95zm-7.45-3.91l1.41 1.41 1.79-1.8-1.41-1.41-1.79 1.8z"/> 109 </svg> 110 </button> 111 </div> 112 <div id="gtoc"> 113 <ul> 114 <li class="pinned-header">Node.js v18.20.1</li> 115 116 <li class="picker-header"> 117 <a href="#"> 118 <span class="collapsed-arrow">►</span><span class="expanded-arrow">▼</span> 119 Table of contents 120 </a> 121 122 <div class="picker"><div class="toc"><ul> 123<li><span class="stability_2"><a href="#vm-executing-javascript">VM (executing JavaScript)</a></span> 124<ul> 125<li><a href="#class-vmscript">Class: <code>vm.Script</code></a> 126<ul> 127<li><a href="#new-vmscriptcode-options"><code>new vm.Script(code[, options])</code></a></li> 128<li><a href="#scriptcacheddatarejected"><code>script.cachedDataRejected</code></a></li> 129<li><a href="#scriptcreatecacheddata"><code>script.createCachedData()</code></a></li> 130<li><a href="#scriptrunincontextcontextifiedobject-options"><code>script.runInContext(contextifiedObject[, options])</code></a></li> 131<li><a href="#scriptruninnewcontextcontextobject-options"><code>script.runInNewContext([contextObject[, options]])</code></a></li> 132<li><a href="#scriptruninthiscontextoptions"><code>script.runInThisContext([options])</code></a></li> 133<li><a href="#scriptsourcemapurl"><code>script.sourceMapURL</code></a></li> 134</ul> 135</li> 136<li><span class="stability_1"><a href="#class-vmmodule">Class: <code>vm.Module</code></a></span> 137<ul> 138<li><a href="#moduledependencyspecifiers"><code>module.dependencySpecifiers</code></a></li> 139<li><a href="#moduleerror"><code>module.error</code></a></li> 140<li><a href="#moduleevaluateoptions"><code>module.evaluate([options])</code></a></li> 141<li><a href="#moduleidentifier"><code>module.identifier</code></a></li> 142<li><a href="#modulelinklinker"><code>module.link(linker)</code></a></li> 143<li><a href="#modulenamespace"><code>module.namespace</code></a></li> 144<li><a href="#modulestatus"><code>module.status</code></a></li> 145</ul> 146</li> 147<li><span class="stability_1"><a href="#class-vmsourcetextmodule">Class: <code>vm.SourceTextModule</code></a></span> 148<ul> 149<li><a href="#new-vmsourcetextmodulecode-options"><code>new vm.SourceTextModule(code[, options])</code></a></li> 150<li><a href="#sourcetextmodulecreatecacheddata"><code>sourceTextModule.createCachedData()</code></a></li> 151</ul> 152</li> 153<li><span class="stability_1"><a href="#class-vmsyntheticmodule">Class: <code>vm.SyntheticModule</code></a></span> 154<ul> 155<li><a href="#new-vmsyntheticmoduleexportnames-evaluatecallback-options"><code>new vm.SyntheticModule(exportNames, evaluateCallback[, options])</code></a></li> 156<li><a href="#syntheticmodulesetexportname-value"><code>syntheticModule.setExport(name, value)</code></a></li> 157</ul> 158</li> 159<li><a href="#vmcompilefunctioncode-params-options"><code>vm.compileFunction(code[, params[, options]])</code></a></li> 160<li><a href="#vmcreatecontextcontextobject-options"><code>vm.createContext([contextObject[, options]])</code></a></li> 161<li><a href="#vmiscontextobject"><code>vm.isContext(object)</code></a></li> 162<li><span class="stability_1"><a href="#vmmeasurememoryoptions"><code>vm.measureMemory([options])</code></a></span></li> 163<li><a href="#vmrunincontextcode-contextifiedobject-options"><code>vm.runInContext(code, contextifiedObject[, options])</code></a></li> 164<li><a href="#vmruninnewcontextcode-contextobject-options"><code>vm.runInNewContext(code[, contextObject[, options]])</code></a></li> 165<li><a href="#vmruninthiscontextcode-options"><code>vm.runInThisContext(code[, options])</code></a></li> 166<li><a href="#example-running-an-http-server-within-a-vm">Example: Running an HTTP server within a VM</a></li> 167<li><a href="#what-does-it-mean-to-contextify-an-object">What does it mean to "contextify" an object?</a></li> 168<li><a href="#timeout-interactions-with-asynchronous-tasks-and-promises">Timeout interactions with asynchronous tasks and Promises</a></li> 169</ul> 170</li> 171</ul></div></div> 172 </li> 173 174 175 <li class="picker-header"> 176 <a href="#"> 177 <span class="collapsed-arrow">►</span><span class="expanded-arrow">▼</span> 178 Index 179 </a> 180 181 <div class="picker"><ul> 182<li><a href="documentation.html" class="nav-documentation">About this documentation</a></li> 183<li><a href="synopsis.html" class="nav-synopsis">Usage and example</a></li> 184 185 <li> 186 <a href="index.html">Index</a> 187 </li> 188 </ul> 189 190<hr class="line"> 191<ul> 192<li><a href="assert.html" class="nav-assert">Assertion testing</a></li> 193<li><a href="async_context.html" class="nav-async_context">Asynchronous context tracking</a></li> 194<li><a href="async_hooks.html" class="nav-async_hooks">Async hooks</a></li> 195<li><a href="buffer.html" class="nav-buffer">Buffer</a></li> 196<li><a href="addons.html" class="nav-addons">C++ addons</a></li> 197<li><a href="n-api.html" class="nav-n-api">C/C++ addons with Node-API</a></li> 198<li><a href="embedding.html" class="nav-embedding">C++ embedder API</a></li> 199<li><a href="child_process.html" class="nav-child_process">Child processes</a></li> 200<li><a href="cluster.html" class="nav-cluster">Cluster</a></li> 201<li><a href="cli.html" class="nav-cli">Command-line options</a></li> 202<li><a href="console.html" class="nav-console">Console</a></li> 203<li><a href="corepack.html" class="nav-corepack">Corepack</a></li> 204<li><a href="crypto.html" class="nav-crypto">Crypto</a></li> 205<li><a href="debugger.html" class="nav-debugger">Debugger</a></li> 206<li><a href="deprecations.html" class="nav-deprecations">Deprecated APIs</a></li> 207<li><a href="diagnostics_channel.html" class="nav-diagnostics_channel">Diagnostics Channel</a></li> 208<li><a href="dns.html" class="nav-dns">DNS</a></li> 209<li><a href="domain.html" class="nav-domain">Domain</a></li> 210<li><a href="errors.html" class="nav-errors">Errors</a></li> 211<li><a href="events.html" class="nav-events">Events</a></li> 212<li><a href="fs.html" class="nav-fs">File system</a></li> 213<li><a href="globals.html" class="nav-globals">Globals</a></li> 214<li><a href="http.html" class="nav-http">HTTP</a></li> 215<li><a href="http2.html" class="nav-http2">HTTP/2</a></li> 216<li><a href="https.html" class="nav-https">HTTPS</a></li> 217<li><a href="inspector.html" class="nav-inspector">Inspector</a></li> 218<li><a href="intl.html" class="nav-intl">Internationalization</a></li> 219<li><a href="modules.html" class="nav-modules">Modules: CommonJS modules</a></li> 220<li><a href="esm.html" class="nav-esm">Modules: ECMAScript modules</a></li> 221<li><a href="module.html" class="nav-module">Modules: <code>node:module</code> API</a></li> 222<li><a href="packages.html" class="nav-packages">Modules: Packages</a></li> 223<li><a href="net.html" class="nav-net">Net</a></li> 224<li><a href="os.html" class="nav-os">OS</a></li> 225<li><a href="path.html" class="nav-path">Path</a></li> 226<li><a href="perf_hooks.html" class="nav-perf_hooks">Performance hooks</a></li> 227<li><a href="permissions.html" class="nav-permissions">Permissions</a></li> 228<li><a href="process.html" class="nav-process">Process</a></li> 229<li><a href="punycode.html" class="nav-punycode">Punycode</a></li> 230<li><a href="querystring.html" class="nav-querystring">Query strings</a></li> 231<li><a href="readline.html" class="nav-readline">Readline</a></li> 232<li><a href="repl.html" class="nav-repl">REPL</a></li> 233<li><a href="report.html" class="nav-report">Report</a></li> 234<li><a href="single-executable-applications.html" class="nav-single-executable-applications">Single executable applications</a></li> 235<li><a href="stream.html" class="nav-stream">Stream</a></li> 236<li><a href="string_decoder.html" class="nav-string_decoder">String decoder</a></li> 237<li><a href="test.html" class="nav-test">Test runner</a></li> 238<li><a href="timers.html" class="nav-timers">Timers</a></li> 239<li><a href="tls.html" class="nav-tls">TLS/SSL</a></li> 240<li><a href="tracing.html" class="nav-tracing">Trace events</a></li> 241<li><a href="tty.html" class="nav-tty">TTY</a></li> 242<li><a href="dgram.html" class="nav-dgram">UDP/datagram</a></li> 243<li><a href="url.html" class="nav-url">URL</a></li> 244<li><a href="util.html" class="nav-util">Utilities</a></li> 245<li><a href="v8.html" class="nav-v8">V8</a></li> 246<li><a href="vm.html" class="nav-vm active">VM</a></li> 247<li><a href="wasi.html" class="nav-wasi">WASI</a></li> 248<li><a href="webcrypto.html" class="nav-webcrypto">Web Crypto API</a></li> 249<li><a href="webstreams.html" class="nav-webstreams">Web Streams API</a></li> 250<li><a href="worker_threads.html" class="nav-worker_threads">Worker threads</a></li> 251<li><a href="zlib.html" class="nav-zlib">Zlib</a></li> 252</ul> 253<hr class="line"> 254<ul> 255<li><a href="https://github.com/nodejs/node" class="nav-https-github-com-nodejs-node">Code repository and issue tracker</a></li> 256</ul></div> 257 </li> 258 259 260 <li class="picker-header"> 261 <a href="#"> 262 <span class="collapsed-arrow">►</span><span class="expanded-arrow">▼</span> 263 Other versions 264 </a> 265 <div class="picker"><ol id="alt-docs"><li><a href="https://nodejs.org/docs/latest-v21.x/api/vm.html">21.x</a></li> 266<li><a href="https://nodejs.org/docs/latest-v20.x/api/vm.html">20.x <b>LTS</b></a></li> 267<li><a href="https://nodejs.org/docs/latest-v19.x/api/vm.html">19.x</a></li> 268<li><a href="https://nodejs.org/docs/latest-v18.x/api/vm.html">18.x <b>LTS</b></a></li> 269<li><a href="https://nodejs.org/docs/latest-v17.x/api/vm.html">17.x</a></li> 270<li><a href="https://nodejs.org/docs/latest-v16.x/api/vm.html">16.x</a></li> 271<li><a href="https://nodejs.org/docs/latest-v15.x/api/vm.html">15.x</a></li> 272<li><a href="https://nodejs.org/docs/latest-v14.x/api/vm.html">14.x</a></li> 273<li><a href="https://nodejs.org/docs/latest-v13.x/api/vm.html">13.x</a></li> 274<li><a href="https://nodejs.org/docs/latest-v12.x/api/vm.html">12.x</a></li> 275<li><a href="https://nodejs.org/docs/latest-v11.x/api/vm.html">11.x</a></li> 276<li><a href="https://nodejs.org/docs/latest-v10.x/api/vm.html">10.x</a></li> 277<li><a href="https://nodejs.org/docs/latest-v9.x/api/vm.html">9.x</a></li> 278<li><a href="https://nodejs.org/docs/latest-v8.x/api/vm.html">8.x</a></li> 279<li><a href="https://nodejs.org/docs/latest-v7.x/api/vm.html">7.x</a></li> 280<li><a href="https://nodejs.org/docs/latest-v6.x/api/vm.html">6.x</a></li> 281<li><a href="https://nodejs.org/docs/latest-v5.x/api/vm.html">5.x</a></li> 282<li><a href="https://nodejs.org/docs/latest-v4.x/api/vm.html">4.x</a></li> 283<li><a href="https://nodejs.org/docs/latest-v0.12.x/api/vm.html">0.12.x</a></li> 284<li><a href="https://nodejs.org/docs/latest-v0.10.x/api/vm.html">0.10.x</a></li></ol></div> 285 </li> 286 287 <li class="picker-header"> 288 <a href="#"> 289 <span class="collapsed-arrow">►</span><span class="expanded-arrow">▼</span> 290 Options 291 </a> 292 293 <div class="picker"> 294 <ul> 295 <li> 296 <a href="all.html">View on single page</a> 297 </li> 298 <li> 299 <a href="vm.json">View as JSON</a> 300 </li> 301 <li class="edit_on_github"><a href="https://github.com/nodejs/node/edit/main/doc/api/vm.md">Edit on GitHub</a></li> 302 </ul> 303 </div> 304 </li> 305 </ul> 306 </div> 307 <hr> 308 </header> 309 310 <details id="toc" open><summary>Table of contents</summary><ul> 311<li><span class="stability_2"><a href="#vm-executing-javascript">VM (executing JavaScript)</a></span> 312<ul> 313<li><a href="#class-vmscript">Class: <code>vm.Script</code></a> 314<ul> 315<li><a href="#new-vmscriptcode-options"><code>new vm.Script(code[, options])</code></a></li> 316<li><a href="#scriptcacheddatarejected"><code>script.cachedDataRejected</code></a></li> 317<li><a href="#scriptcreatecacheddata"><code>script.createCachedData()</code></a></li> 318<li><a href="#scriptrunincontextcontextifiedobject-options"><code>script.runInContext(contextifiedObject[, options])</code></a></li> 319<li><a href="#scriptruninnewcontextcontextobject-options"><code>script.runInNewContext([contextObject[, options]])</code></a></li> 320<li><a href="#scriptruninthiscontextoptions"><code>script.runInThisContext([options])</code></a></li> 321<li><a href="#scriptsourcemapurl"><code>script.sourceMapURL</code></a></li> 322</ul> 323</li> 324<li><span class="stability_1"><a href="#class-vmmodule">Class: <code>vm.Module</code></a></span> 325<ul> 326<li><a href="#moduledependencyspecifiers"><code>module.dependencySpecifiers</code></a></li> 327<li><a href="#moduleerror"><code>module.error</code></a></li> 328<li><a href="#moduleevaluateoptions"><code>module.evaluate([options])</code></a></li> 329<li><a href="#moduleidentifier"><code>module.identifier</code></a></li> 330<li><a href="#modulelinklinker"><code>module.link(linker)</code></a></li> 331<li><a href="#modulenamespace"><code>module.namespace</code></a></li> 332<li><a href="#modulestatus"><code>module.status</code></a></li> 333</ul> 334</li> 335<li><span class="stability_1"><a href="#class-vmsourcetextmodule">Class: <code>vm.SourceTextModule</code></a></span> 336<ul> 337<li><a href="#new-vmsourcetextmodulecode-options"><code>new vm.SourceTextModule(code[, options])</code></a></li> 338<li><a href="#sourcetextmodulecreatecacheddata"><code>sourceTextModule.createCachedData()</code></a></li> 339</ul> 340</li> 341<li><span class="stability_1"><a href="#class-vmsyntheticmodule">Class: <code>vm.SyntheticModule</code></a></span> 342<ul> 343<li><a href="#new-vmsyntheticmoduleexportnames-evaluatecallback-options"><code>new vm.SyntheticModule(exportNames, evaluateCallback[, options])</code></a></li> 344<li><a href="#syntheticmodulesetexportname-value"><code>syntheticModule.setExport(name, value)</code></a></li> 345</ul> 346</li> 347<li><a href="#vmcompilefunctioncode-params-options"><code>vm.compileFunction(code[, params[, options]])</code></a></li> 348<li><a href="#vmcreatecontextcontextobject-options"><code>vm.createContext([contextObject[, options]])</code></a></li> 349<li><a href="#vmiscontextobject"><code>vm.isContext(object)</code></a></li> 350<li><span class="stability_1"><a href="#vmmeasurememoryoptions"><code>vm.measureMemory([options])</code></a></span></li> 351<li><a href="#vmrunincontextcode-contextifiedobject-options"><code>vm.runInContext(code, contextifiedObject[, options])</code></a></li> 352<li><a href="#vmruninnewcontextcode-contextobject-options"><code>vm.runInNewContext(code[, contextObject[, options]])</code></a></li> 353<li><a href="#vmruninthiscontextcode-options"><code>vm.runInThisContext(code[, options])</code></a></li> 354<li><a href="#example-running-an-http-server-within-a-vm">Example: Running an HTTP server within a VM</a></li> 355<li><a href="#what-does-it-mean-to-contextify-an-object">What does it mean to "contextify" an object?</a></li> 356<li><a href="#timeout-interactions-with-asynchronous-tasks-and-promises">Timeout interactions with asynchronous tasks and Promises</a></li> 357</ul> 358</li> 359</ul></details> 360 361 <div id="apicontent"> 362 <h2>VM (executing JavaScript)<span><a class="mark" href="#vm-executing-javascript" id="vm-executing-javascript">#</a></span><a aria-hidden="true" class="legacy" id="vm_vm_executing_javascript"></a></h2> 363 364<p></p><div class="api_stability api_stability_2"><a href="documentation.html#stability-index">Stability: 2</a> - Stable</div><p></p> 365 366<p><strong>Source Code:</strong> <a href="https://github.com/nodejs/node/blob/v18.20.1/lib/vm.js">lib/vm.js</a></p> 367<p>The <code>node:vm</code> module enables compiling and running code within V8 Virtual 368Machine contexts.</p> 369<p><strong class="critical">The <code>node:vm</code> module is not a security 370mechanism. Do not use it to run untrusted code.</strong></p> 371<p>JavaScript code can be compiled and run immediately or 372compiled, saved, and run later.</p> 373<p>A common use case is to run the code in a different V8 Context. This means 374invoked code has a different global object than the invoking code.</p> 375<p>One can provide the context by <a href="#what-does-it-mean-to-contextify-an-object"><em>contextifying</em></a> an 376object. The invoked code treats any property in the context like a 377global variable. Any changes to global variables caused by the invoked 378code are reflected in the context object.</p> 379<pre><code class="language-js"><span class="hljs-keyword">const</span> vm = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:vm'</span>); 380 381<span class="hljs-keyword">const</span> x = <span class="hljs-number">1</span>; 382 383<span class="hljs-keyword">const</span> context = { <span class="hljs-attr">x</span>: <span class="hljs-number">2</span> }; 384vm.<span class="hljs-title function_">createContext</span>(context); <span class="hljs-comment">// Contextify the object.</span> 385 386<span class="hljs-keyword">const</span> code = <span class="hljs-string">'x += 40; var y = 17;'</span>; 387<span class="hljs-comment">// `x` and `y` are global variables in the context.</span> 388<span class="hljs-comment">// Initially, x has the value 2 because that is the value of context.x.</span> 389vm.<span class="hljs-title function_">runInContext</span>(code, context); 390 391<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(context.<span class="hljs-property">x</span>); <span class="hljs-comment">// 42</span> 392<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(context.<span class="hljs-property">y</span>); <span class="hljs-comment">// 17</span> 393 394<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(x); <span class="hljs-comment">// 1; y is not defined.</span></code> <button class="copy-button">copy</button></pre> 395<section><h3>Class: <code>vm.Script</code><span><a class="mark" href="#class-vmscript" id="class-vmscript">#</a></span><a aria-hidden="true" class="legacy" id="vm_class_vm_script"></a></h3> 396<div class="api_metadata"> 397<span>Added in: v0.3.1</span> 398</div> 399<p>Instances of the <code>vm.Script</code> class contain precompiled scripts that can be 400executed in specific contexts.</p> 401<h4><code>new vm.Script(code[, options])</code><span><a class="mark" href="#new-vmscriptcode-options" id="new-vmscriptcode-options">#</a></span><a aria-hidden="true" class="legacy" id="vm_new_vm_script_code_options"></a></h4> 402<div class="api_metadata"> 403<details class="changelog"><summary>History</summary> 404<table> 405<tbody><tr><th>Version</th><th>Changes</th></tr> 406<tr><td>v17.0.0, v16.12.0</td> 407<td><p>Added support for import attributes to the <code>importModuleDynamically</code> parameter.</p></td></tr> 408<tr><td>v10.6.0</td> 409<td><p>The <code>produceCachedData</code> is deprecated in favour of <code>script.createCachedData()</code>.</p></td></tr> 410<tr><td>v5.7.0</td> 411<td><p>The <code>cachedData</code> and <code>produceCachedData</code> options are supported now.</p></td></tr> 412<tr><td>v0.3.1</td> 413<td><p><span>Added in: v0.3.1</span></p></td></tr> 414</tbody></table> 415</details> 416</div> 417<ul> 418<li><code>code</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> The JavaScript code to compile.</li> 419<li><code>options</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> 420<ul> 421<li><code>filename</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> Specifies the filename used in stack traces produced 422by this script. <strong>Default:</strong> <code>'evalmachine.<anonymous>'</code>.</li> 423<li><code>lineOffset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><number></a> Specifies the line number offset that is displayed 424in stack traces produced by this script. <strong>Default:</strong> <code>0</code>.</li> 425<li><code>columnOffset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><number></a> Specifies the first-line column number offset that 426is displayed in stack traces produced by this script. <strong>Default:</strong> <code>0</code>.</li> 427<li><code>cachedData</code> <a href="buffer.html#class-buffer" class="type"><Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type"><TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type"><DataView></a> Provides an optional <code>Buffer</code> or 428<code>TypedArray</code>, or <code>DataView</code> with V8's code cache data for the supplied 429source. When supplied, the <code>cachedDataRejected</code> value will be set to 430either <code>true</code> or <code>false</code> depending on acceptance of the data by V8.</li> 431<li><code>produceCachedData</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type"><boolean></a> When <code>true</code> and no <code>cachedData</code> is present, V8 432will attempt to produce code cache data for <code>code</code>. Upon success, a 433<code>Buffer</code> with V8's code cache data will be produced and stored in the 434<code>cachedData</code> property of the returned <code>vm.Script</code> instance. 435The <code>cachedDataProduced</code> value will be set to either <code>true</code> or <code>false</code> 436depending on whether code cache data is produced successfully. 437This option is <strong>deprecated</strong> in favor of <code>script.createCachedData()</code>. 438<strong>Default:</strong> <code>false</code>.</li> 439<li><code>importModuleDynamically</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function" class="type"><Function></a> Called during evaluation of this module 440when <code>import()</code> is called. If this option is not specified, calls to 441<code>import()</code> will reject with <a href="errors.html#err_vm_dynamic_import_callback_missing"><code>ERR_VM_DYNAMIC_IMPORT_CALLBACK_MISSING</code></a>. 442This option is part of the experimental modules API. We do not recommend 443using it in a production environment. If <code>--experimental-vm-modules</code> isn't 444set, this callback will be ignored and calls to <code>import()</code> will reject with 445<a href="errors.html#err_vm_dynamic_import_callback_missing_flag"><code>ERR_VM_DYNAMIC_IMPORT_CALLBACK_MISSING_FLAG</code></a>. 446<ul> 447<li><code>specifier</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> specifier passed to <code>import()</code></li> 448<li><code>script</code> <a href="vm.html#class-vmscript" class="type"><vm.Script></a></li> 449<li><code>importAttributes</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a> The <code>"with"</code> value passed to the 450<a href="https://tc39.es/proposal-import-attributes/#sec-evaluate-import-call"><code>optionsExpression</code></a> optional parameter, or an empty object if no value 451was provided.</li> 452<li>Returns: <a href="https://tc39.github.io/ecma262/#sec-module-namespace-exotic-objects" class="type"><Module Namespace Object></a> | <a href="vm.html#class-vmmodule" class="type"><vm.Module></a> Returning a <code>vm.Module</code> is 453recommended in order to take advantage of error tracking, and to avoid 454issues with namespaces that contain <code>then</code> function exports.</li> 455</ul> 456</li> 457</ul> 458</li> 459</ul> 460<p>If <code>options</code> is a string, then it specifies the filename.</p> 461<p>Creating a new <code>vm.Script</code> object compiles <code>code</code> but does not run it. The 462compiled <code>vm.Script</code> can be run later multiple times. The <code>code</code> is not bound to 463any global object; rather, it is bound before each run, just for that run.</p> 464<h4><code>script.cachedDataRejected</code><span><a class="mark" href="#scriptcacheddatarejected" id="scriptcacheddatarejected">#</a></span><a aria-hidden="true" class="legacy" id="vm_script_cacheddatarejected"></a></h4> 465<div class="api_metadata"> 466<span>Added in: v5.7.0</span> 467</div> 468<ul> 469<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type"><boolean></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Undefined_type" class="type"><undefined></a></li> 470</ul> 471<p>When <code>cachedData</code> is supplied to create the <code>vm.Script</code>, this value will be set 472to either <code>true</code> or <code>false</code> depending on acceptance of the data by V8. 473Otherwise the value is <code>undefined</code>.</p> 474<h4><code>script.createCachedData()</code><span><a class="mark" href="#scriptcreatecacheddata" id="scriptcreatecacheddata">#</a></span><a aria-hidden="true" class="legacy" id="vm_script_createcacheddata"></a></h4> 475<div class="api_metadata"> 476<span>Added in: v10.6.0</span> 477</div> 478<ul> 479<li>Returns: <a href="buffer.html#class-buffer" class="type"><Buffer></a></li> 480</ul> 481<p>Creates a code cache that can be used with the <code>Script</code> constructor's 482<code>cachedData</code> option. Returns a <code>Buffer</code>. This method may be called at any 483time and any number of times.</p> 484<p>The code cache of the <code>Script</code> doesn't contain any JavaScript observable 485states. The code cache is safe to be saved along side the script source and 486used to construct new <code>Script</code> instances multiple times.</p> 487<p>Functions in the <code>Script</code> source can be marked as lazily compiled and they are 488not compiled at construction of the <code>Script</code>. These functions are going to be 489compiled when they are invoked the first time. The code cache serializes the 490metadata that V8 currently knows about the <code>Script</code> that it can use to speed up 491future compilations.</p> 492<pre><code class="language-js"><span class="hljs-keyword">const</span> script = <span class="hljs-keyword">new</span> vm.<span class="hljs-title class_">Script</span>(<span class="hljs-string">` 493function add(a, b) { 494 return a + b; 495} 496 497const x = add(1, 2); 498`</span>); 499 500<span class="hljs-keyword">const</span> cacheWithoutAdd = script.<span class="hljs-title function_">createCachedData</span>(); 501<span class="hljs-comment">// In `cacheWithoutAdd` the function `add()` is marked for full compilation</span> 502<span class="hljs-comment">// upon invocation.</span> 503 504script.<span class="hljs-title function_">runInThisContext</span>(); 505 506<span class="hljs-keyword">const</span> cacheWithAdd = script.<span class="hljs-title function_">createCachedData</span>(); 507<span class="hljs-comment">// `cacheWithAdd` contains fully compiled function `add()`.</span></code> <button class="copy-button">copy</button></pre> 508<h4><code>script.runInContext(contextifiedObject[, options])</code><span><a class="mark" href="#scriptrunincontextcontextifiedobject-options" id="scriptrunincontextcontextifiedobject-options">#</a></span><a aria-hidden="true" class="legacy" id="vm_script_runincontext_contextifiedobject_options"></a></h4> 509<div class="api_metadata"> 510<details class="changelog"><summary>History</summary> 511<table> 512<tbody><tr><th>Version</th><th>Changes</th></tr> 513<tr><td>v6.3.0</td> 514<td><p>The <code>breakOnSigint</code> option is supported now.</p></td></tr> 515<tr><td>v0.3.1</td> 516<td><p><span>Added in: v0.3.1</span></p></td></tr> 517</tbody></table> 518</details> 519</div> 520<ul> 521<li><code>contextifiedObject</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a> A <a href="#what-does-it-mean-to-contextify-an-object">contextified</a> object as returned by the 522<code>vm.createContext()</code> method.</li> 523<li><code>options</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a> 524<ul> 525<li><code>displayErrors</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type"><boolean></a> When <code>true</code>, if an <a href="errors.html#class-error"><code>Error</code></a> occurs 526while compiling the <code>code</code>, the line of code causing the error is attached 527to the stack trace. <strong>Default:</strong> <code>true</code>.</li> 528<li><code>timeout</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Specifies the number of milliseconds to execute <code>code</code> 529before terminating execution. If execution is terminated, an <a href="errors.html#class-error"><code>Error</code></a> 530will be thrown. This value must be a strictly positive integer.</li> 531<li><code>breakOnSigint</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type"><boolean></a> If <code>true</code>, receiving <code>SIGINT</code> 532(<kbd>Ctrl</kbd>+<kbd>C</kbd>) will terminate execution and throw an 533<a href="errors.html#class-error"><code>Error</code></a>. Existing handlers for the event that have been attached via 534<code>process.on('SIGINT')</code> are disabled during script execution, but continue to 535work after that. <strong>Default:</strong> <code>false</code>.</li> 536</ul> 537</li> 538<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type"><any></a> the result of the very last statement executed in the script.</li> 539</ul> 540<p>Runs the compiled code contained by the <code>vm.Script</code> object within the given 541<code>contextifiedObject</code> and returns the result. Running code does not have access 542to local scope.</p> 543<p>The following example compiles code that increments a global variable, sets 544the value of another global variable, then execute the code multiple times. 545The globals are contained in the <code>context</code> object.</p> 546<pre><code class="language-js"><span class="hljs-keyword">const</span> vm = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:vm'</span>); 547 548<span class="hljs-keyword">const</span> context = { 549 <span class="hljs-attr">animal</span>: <span class="hljs-string">'cat'</span>, 550 <span class="hljs-attr">count</span>: <span class="hljs-number">2</span>, 551}; 552 553<span class="hljs-keyword">const</span> script = <span class="hljs-keyword">new</span> vm.<span class="hljs-title class_">Script</span>(<span class="hljs-string">'count += 1; name = "kitty";'</span>); 554 555vm.<span class="hljs-title function_">createContext</span>(context); 556<span class="hljs-keyword">for</span> (<span class="hljs-keyword">let</span> i = <span class="hljs-number">0</span>; i < <span class="hljs-number">10</span>; ++i) { 557 script.<span class="hljs-title function_">runInContext</span>(context); 558} 559 560<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(context); 561<span class="hljs-comment">// Prints: { animal: 'cat', count: 12, name: 'kitty' }</span></code> <button class="copy-button">copy</button></pre> 562<p>Using the <code>timeout</code> or <code>breakOnSigint</code> options will result in new event loops 563and corresponding threads being started, which have a non-zero performance 564overhead.</p> 565<h4><code>script.runInNewContext([contextObject[, options]])</code><span><a class="mark" href="#scriptruninnewcontextcontextobject-options" id="scriptruninnewcontextcontextobject-options">#</a></span><a aria-hidden="true" class="legacy" id="vm_script_runinnewcontext_contextobject_options"></a></h4> 566<div class="api_metadata"> 567<details class="changelog"><summary>History</summary> 568<table> 569<tbody><tr><th>Version</th><th>Changes</th></tr> 570<tr><td>v14.6.0</td> 571<td><p>The <code>microtaskMode</code> option is supported now.</p></td></tr> 572<tr><td>v10.0.0</td> 573<td><p>The <code>contextCodeGeneration</code> option is supported now.</p></td></tr> 574<tr><td>v6.3.0</td> 575<td><p>The <code>breakOnSigint</code> option is supported now.</p></td></tr> 576<tr><td>v0.3.1</td> 577<td><p><span>Added in: v0.3.1</span></p></td></tr> 578</tbody></table> 579</details> 580</div> 581<ul> 582<li><code>contextObject</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a> An object that will be <a href="#what-does-it-mean-to-contextify-an-object">contextified</a>. If 583<code>undefined</code>, a new object will be created.</li> 584<li><code>options</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a> 585<ul> 586<li><code>displayErrors</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type"><boolean></a> When <code>true</code>, if an <a href="errors.html#class-error"><code>Error</code></a> occurs 587while compiling the <code>code</code>, the line of code causing the error is attached 588to the stack trace. <strong>Default:</strong> <code>true</code>.</li> 589<li><code>timeout</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Specifies the number of milliseconds to execute <code>code</code> 590before terminating execution. If execution is terminated, an <a href="errors.html#class-error"><code>Error</code></a> 591will be thrown. This value must be a strictly positive integer.</li> 592<li><code>breakOnSigint</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type"><boolean></a> If <code>true</code>, receiving <code>SIGINT</code> 593(<kbd>Ctrl</kbd>+<kbd>C</kbd>) will terminate execution and throw an 594<a href="errors.html#class-error"><code>Error</code></a>. Existing handlers for the event that have been attached via 595<code>process.on('SIGINT')</code> are disabled during script execution, but continue to 596work after that. <strong>Default:</strong> <code>false</code>.</li> 597<li><code>contextName</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> Human-readable name of the newly created context. 598<strong>Default:</strong> <code>'VM Context i'</code>, where <code>i</code> is an ascending numerical index of 599the created context.</li> 600<li><code>contextOrigin</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> <a href="https://developer.mozilla.org/en-US/docs/Glossary/Origin">Origin</a> corresponding to the newly 601created context for display purposes. The origin should be formatted like a 602URL, but with only the scheme, host, and port (if necessary), like the 603value of the <a href="url.html#urlorigin"><code>url.origin</code></a> property of a <a href="url.html#class-url"><code>URL</code></a> object. Most notably, 604this string should omit the trailing slash, as that denotes a path. 605<strong>Default:</strong> <code>''</code>.</li> 606<li><code>contextCodeGeneration</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a> 607<ul> 608<li><code>strings</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type"><boolean></a> If set to false any calls to <code>eval</code> or function 609constructors (<code>Function</code>, <code>GeneratorFunction</code>, etc) will throw an 610<code>EvalError</code>. <strong>Default:</strong> <code>true</code>.</li> 611<li><code>wasm</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type"><boolean></a> If set to false any attempt to compile a WebAssembly 612module will throw a <code>WebAssembly.CompileError</code>. <strong>Default:</strong> <code>true</code>.</li> 613</ul> 614</li> 615<li><code>microtaskMode</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> If set to <code>afterEvaluate</code>, microtasks (tasks 616scheduled through <code>Promise</code>s and <code>async function</code>s) will be run immediately 617after the script has run. They are included in the <code>timeout</code> and 618<code>breakOnSigint</code> scopes in that case.</li> 619</ul> 620</li> 621<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type"><any></a> the result of the very last statement executed in the script.</li> 622</ul> 623<p>First contextifies the given <code>contextObject</code>, runs the compiled code contained 624by the <code>vm.Script</code> object within the created context, and returns the result. 625Running code does not have access to local scope.</p> 626<p>The following example compiles code that sets a global variable, then executes 627the code multiple times in different contexts. The globals are set on and 628contained within each individual <code>context</code>.</p> 629<pre><code class="language-js"><span class="hljs-keyword">const</span> vm = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:vm'</span>); 630 631<span class="hljs-keyword">const</span> script = <span class="hljs-keyword">new</span> vm.<span class="hljs-title class_">Script</span>(<span class="hljs-string">'globalVar = "set"'</span>); 632 633<span class="hljs-keyword">const</span> contexts = [{}, {}, {}]; 634contexts.<span class="hljs-title function_">forEach</span>(<span class="hljs-function">(<span class="hljs-params">context</span>) =></span> { 635 script.<span class="hljs-title function_">runInNewContext</span>(context); 636}); 637 638<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(contexts); 639<span class="hljs-comment">// Prints: [{ globalVar: 'set' }, { globalVar: 'set' }, { globalVar: 'set' }]</span></code> <button class="copy-button">copy</button></pre> 640<h4><code>script.runInThisContext([options])</code><span><a class="mark" href="#scriptruninthiscontextoptions" id="scriptruninthiscontextoptions">#</a></span><a aria-hidden="true" class="legacy" id="vm_script_runinthiscontext_options"></a></h4> 641<div class="api_metadata"> 642<details class="changelog"><summary>History</summary> 643<table> 644<tbody><tr><th>Version</th><th>Changes</th></tr> 645<tr><td>v6.3.0</td> 646<td><p>The <code>breakOnSigint</code> option is supported now.</p></td></tr> 647<tr><td>v0.3.1</td> 648<td><p><span>Added in: v0.3.1</span></p></td></tr> 649</tbody></table> 650</details> 651</div> 652<ul> 653<li><code>options</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a> 654<ul> 655<li><code>displayErrors</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type"><boolean></a> When <code>true</code>, if an <a href="errors.html#class-error"><code>Error</code></a> occurs 656while compiling the <code>code</code>, the line of code causing the error is attached 657to the stack trace. <strong>Default:</strong> <code>true</code>.</li> 658<li><code>timeout</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Specifies the number of milliseconds to execute <code>code</code> 659before terminating execution. If execution is terminated, an <a href="errors.html#class-error"><code>Error</code></a> 660will be thrown. This value must be a strictly positive integer.</li> 661<li><code>breakOnSigint</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type"><boolean></a> If <code>true</code>, receiving <code>SIGINT</code> 662(<kbd>Ctrl</kbd>+<kbd>C</kbd>) will terminate execution and throw an 663<a href="errors.html#class-error"><code>Error</code></a>. Existing handlers for the event that have been attached via 664<code>process.on('SIGINT')</code> are disabled during script execution, but continue to 665work after that. <strong>Default:</strong> <code>false</code>.</li> 666</ul> 667</li> 668<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type"><any></a> the result of the very last statement executed in the script.</li> 669</ul> 670<p>Runs the compiled code contained by the <code>vm.Script</code> within the context of the 671current <code>global</code> object. Running code does not have access to local scope, but 672<em>does</em> have access to the current <code>global</code> object.</p> 673<p>The following example compiles code that increments a <code>global</code> variable then 674executes that code multiple times:</p> 675<pre><code class="language-js"><span class="hljs-keyword">const</span> vm = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:vm'</span>); 676 677<span class="hljs-variable language_">global</span>.<span class="hljs-property">globalVar</span> = <span class="hljs-number">0</span>; 678 679<span class="hljs-keyword">const</span> script = <span class="hljs-keyword">new</span> vm.<span class="hljs-title class_">Script</span>(<span class="hljs-string">'globalVar += 1'</span>, { <span class="hljs-attr">filename</span>: <span class="hljs-string">'myfile.vm'</span> }); 680 681<span class="hljs-keyword">for</span> (<span class="hljs-keyword">let</span> i = <span class="hljs-number">0</span>; i < <span class="hljs-number">1000</span>; ++i) { 682 script.<span class="hljs-title function_">runInThisContext</span>(); 683} 684 685<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(globalVar); 686 687<span class="hljs-comment">// 1000</span></code> <button class="copy-button">copy</button></pre> 688<h4><code>script.sourceMapURL</code><span><a class="mark" href="#scriptsourcemapurl" id="scriptsourcemapurl">#</a></span><a aria-hidden="true" class="legacy" id="vm_script_sourcemapurl"></a></h4> 689<div class="api_metadata"> 690<span>Added in: v18.13.0</span> 691</div> 692<ul> 693<li><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#Undefined_type" class="type"><undefined></a></li> 694</ul> 695<p>When the script is compiled from a source that contains a source map magic 696comment, this property will be set to the URL of the source map.</p> 697 698<pre class="with-30-chars"><input class="js-flavor-selector" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> vm <span class="hljs-keyword">from</span> <span class="hljs-string">'node:vm'</span>; 699 700<span class="hljs-keyword">const</span> script = <span class="hljs-keyword">new</span> vm.<span class="hljs-title class_">Script</span>(<span class="hljs-string">` 701function myFunc() {} 702//# sourceMappingURL=sourcemap.json 703`</span>); 704 705<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(script.<span class="hljs-property">sourceMapURL</span>); 706<span class="hljs-comment">// Prints: sourcemap.json</span></code><code class="language-js cjs"><span class="hljs-keyword">const</span> vm = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:vm'</span>); 707 708<span class="hljs-keyword">const</span> script = <span class="hljs-keyword">new</span> vm.<span class="hljs-title class_">Script</span>(<span class="hljs-string">` 709function myFunc() {} 710//# sourceMappingURL=sourcemap.json 711`</span>); 712 713<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(script.<span class="hljs-property">sourceMapURL</span>); 714<span class="hljs-comment">// Prints: sourcemap.json</span></code><button class="copy-button">copy</button></pre> 715</section><section><h3>Class: <code>vm.Module</code><span><a class="mark" href="#class-vmmodule" id="class-vmmodule">#</a></span><a aria-hidden="true" class="legacy" id="vm_class_vm_module"></a></h3> 716<div class="api_metadata"> 717<span>Added in: v13.0.0, v12.16.0</span> 718</div> 719<p></p><div class="api_stability api_stability_1"><a href="documentation.html#stability-index">Stability: 1</a> - Experimental</div><p></p> 720<p>This feature is only available with the <code>--experimental-vm-modules</code> command 721flag enabled.</p> 722<p>The <code>vm.Module</code> class provides a low-level interface for using 723ECMAScript modules in VM contexts. It is the counterpart of the <code>vm.Script</code> 724class that closely mirrors <a href="https://www.ecma-international.org/ecma-262/#sec-abstract-module-records">Module Record</a>s as defined in the ECMAScript 725specification.</p> 726<p>Unlike <code>vm.Script</code> however, every <code>vm.Module</code> object is bound to a context from 727its creation. Operations on <code>vm.Module</code> objects are intrinsically asynchronous, 728in contrast with the synchronous nature of <code>vm.Script</code> objects. The use of 729'async' functions can help with manipulating <code>vm.Module</code> objects.</p> 730<p>Using a <code>vm.Module</code> object requires three distinct steps: creation/parsing, 731linking, and evaluation. These three steps are illustrated in the following 732example.</p> 733<p>This implementation lies at a lower level than the <a href="esm.html#modules-ecmascript-modules">ECMAScript Module 734loader</a>. There is also no way to interact with the Loader yet, though 735support is planned.</p> 736 737<pre class="with-30-chars"><input class="js-flavor-selector" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> vm <span class="hljs-keyword">from</span> <span class="hljs-string">'node:vm'</span>; 738 739<span class="hljs-keyword">const</span> contextifiedObject = vm.<span class="hljs-title function_">createContext</span>({ 740 <span class="hljs-attr">secret</span>: <span class="hljs-number">42</span>, 741 <span class="hljs-attr">print</span>: <span class="hljs-variable language_">console</span>.<span class="hljs-property">log</span>, 742}); 743 744<span class="hljs-comment">// Step 1</span> 745<span class="hljs-comment">//</span> 746<span class="hljs-comment">// Create a Module by constructing a new `vm.SourceTextModule` object. This</span> 747<span class="hljs-comment">// parses the provided source text, throwing a `SyntaxError` if anything goes</span> 748<span class="hljs-comment">// wrong. By default, a Module is created in the top context. But here, we</span> 749<span class="hljs-comment">// specify `contextifiedObject` as the context this Module belongs to.</span> 750<span class="hljs-comment">//</span> 751<span class="hljs-comment">// Here, we attempt to obtain the default export from the module "foo", and</span> 752<span class="hljs-comment">// put it into local binding "secret".</span> 753 754<span class="hljs-keyword">const</span> bar = <span class="hljs-keyword">new</span> vm.<span class="hljs-title class_">SourceTextModule</span>(<span class="hljs-string">` 755 import s from 'foo'; 756 s; 757 print(s); 758`</span>, { <span class="hljs-attr">context</span>: contextifiedObject }); 759 760<span class="hljs-comment">// Step 2</span> 761<span class="hljs-comment">//</span> 762<span class="hljs-comment">// "Link" the imported dependencies of this Module to it.</span> 763<span class="hljs-comment">//</span> 764<span class="hljs-comment">// The provided linking callback (the "linker") accepts two arguments: the</span> 765<span class="hljs-comment">// parent module (`bar` in this case) and the string that is the specifier of</span> 766<span class="hljs-comment">// the imported module. The callback is expected to return a Module that</span> 767<span class="hljs-comment">// corresponds to the provided specifier, with certain requirements documented</span> 768<span class="hljs-comment">// in `module.link()`.</span> 769<span class="hljs-comment">//</span> 770<span class="hljs-comment">// If linking has not started for the returned Module, the same linker</span> 771<span class="hljs-comment">// callback will be called on the returned Module.</span> 772<span class="hljs-comment">//</span> 773<span class="hljs-comment">// Even top-level Modules without dependencies must be explicitly linked. The</span> 774<span class="hljs-comment">// callback provided would never be called, however.</span> 775<span class="hljs-comment">//</span> 776<span class="hljs-comment">// The link() method returns a Promise that will be resolved when all the</span> 777<span class="hljs-comment">// Promises returned by the linker resolve.</span> 778<span class="hljs-comment">//</span> 779<span class="hljs-comment">// Note: This is a contrived example in that the linker function creates a new</span> 780<span class="hljs-comment">// "foo" module every time it is called. In a full-fledged module system, a</span> 781<span class="hljs-comment">// cache would probably be used to avoid duplicated modules.</span> 782 783<span class="hljs-keyword">async</span> <span class="hljs-keyword">function</span> <span class="hljs-title function_">linker</span>(<span class="hljs-params">specifier, referencingModule</span>) { 784 <span class="hljs-keyword">if</span> (specifier === <span class="hljs-string">'foo'</span>) { 785 <span class="hljs-keyword">return</span> <span class="hljs-keyword">new</span> vm.<span class="hljs-title class_">SourceTextModule</span>(<span class="hljs-string">` 786 // The "secret" variable refers to the global variable we added to 787 // "contextifiedObject" when creating the context. 788 export default secret; 789 `</span>, { <span class="hljs-attr">context</span>: referencingModule.<span class="hljs-property">context</span> }); 790 791 <span class="hljs-comment">// Using `contextifiedObject` instead of `referencingModule.context`</span> 792 <span class="hljs-comment">// here would work as well.</span> 793 } 794 <span class="hljs-keyword">throw</span> <span class="hljs-keyword">new</span> <span class="hljs-title class_">Error</span>(<span class="hljs-string">`Unable to resolve dependency: <span class="hljs-subst">${specifier}</span>`</span>); 795} 796<span class="hljs-keyword">await</span> bar.<span class="hljs-title function_">link</span>(linker); 797 798<span class="hljs-comment">// Step 3</span> 799<span class="hljs-comment">//</span> 800<span class="hljs-comment">// Evaluate the Module. The evaluate() method returns a promise which will</span> 801<span class="hljs-comment">// resolve after the module has finished evaluating.</span> 802 803<span class="hljs-comment">// Prints 42.</span> 804<span class="hljs-keyword">await</span> bar.evaluate();</code><code class="language-js cjs"><span class="hljs-keyword">const</span> vm = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:vm'</span>); 805 806<span class="hljs-keyword">const</span> contextifiedObject = vm.<span class="hljs-title function_">createContext</span>({ 807 <span class="hljs-attr">secret</span>: <span class="hljs-number">42</span>, 808 <span class="hljs-attr">print</span>: <span class="hljs-variable language_">console</span>.<span class="hljs-property">log</span>, 809}); 810 811(<span class="hljs-keyword">async</span> () => { 812 <span class="hljs-comment">// Step 1</span> 813 <span class="hljs-comment">//</span> 814 <span class="hljs-comment">// Create a Module by constructing a new `vm.SourceTextModule` object. This</span> 815 <span class="hljs-comment">// parses the provided source text, throwing a `SyntaxError` if anything goes</span> 816 <span class="hljs-comment">// wrong. By default, a Module is created in the top context. But here, we</span> 817 <span class="hljs-comment">// specify `contextifiedObject` as the context this Module belongs to.</span> 818 <span class="hljs-comment">//</span> 819 <span class="hljs-comment">// Here, we attempt to obtain the default export from the module "foo", and</span> 820 <span class="hljs-comment">// put it into local binding "secret".</span> 821 822 <span class="hljs-keyword">const</span> bar = <span class="hljs-keyword">new</span> vm.<span class="hljs-title class_">SourceTextModule</span>(<span class="hljs-string">` 823 import s from 'foo'; 824 s; 825 print(s); 826 `</span>, { <span class="hljs-attr">context</span>: contextifiedObject }); 827 828 <span class="hljs-comment">// Step 2</span> 829 <span class="hljs-comment">//</span> 830 <span class="hljs-comment">// "Link" the imported dependencies of this Module to it.</span> 831 <span class="hljs-comment">//</span> 832 <span class="hljs-comment">// The provided linking callback (the "linker") accepts two arguments: the</span> 833 <span class="hljs-comment">// parent module (`bar` in this case) and the string that is the specifier of</span> 834 <span class="hljs-comment">// the imported module. The callback is expected to return a Module that</span> 835 <span class="hljs-comment">// corresponds to the provided specifier, with certain requirements documented</span> 836 <span class="hljs-comment">// in `module.link()`.</span> 837 <span class="hljs-comment">//</span> 838 <span class="hljs-comment">// If linking has not started for the returned Module, the same linker</span> 839 <span class="hljs-comment">// callback will be called on the returned Module.</span> 840 <span class="hljs-comment">//</span> 841 <span class="hljs-comment">// Even top-level Modules without dependencies must be explicitly linked. The</span> 842 <span class="hljs-comment">// callback provided would never be called, however.</span> 843 <span class="hljs-comment">//</span> 844 <span class="hljs-comment">// The link() method returns a Promise that will be resolved when all the</span> 845 <span class="hljs-comment">// Promises returned by the linker resolve.</span> 846 <span class="hljs-comment">//</span> 847 <span class="hljs-comment">// Note: This is a contrived example in that the linker function creates a new</span> 848 <span class="hljs-comment">// "foo" module every time it is called. In a full-fledged module system, a</span> 849 <span class="hljs-comment">// cache would probably be used to avoid duplicated modules.</span> 850 851 <span class="hljs-keyword">async</span> <span class="hljs-keyword">function</span> <span class="hljs-title function_">linker</span>(<span class="hljs-params">specifier, referencingModule</span>) { 852 <span class="hljs-keyword">if</span> (specifier === <span class="hljs-string">'foo'</span>) { 853 <span class="hljs-keyword">return</span> <span class="hljs-keyword">new</span> vm.<span class="hljs-title class_">SourceTextModule</span>(<span class="hljs-string">` 854 // The "secret" variable refers to the global variable we added to 855 // "contextifiedObject" when creating the context. 856 export default secret; 857 `</span>, { <span class="hljs-attr">context</span>: referencingModule.<span class="hljs-property">context</span> }); 858 859 <span class="hljs-comment">// Using `contextifiedObject` instead of `referencingModule.context`</span> 860 <span class="hljs-comment">// here would work as well.</span> 861 } 862 <span class="hljs-keyword">throw</span> <span class="hljs-keyword">new</span> <span class="hljs-title class_">Error</span>(<span class="hljs-string">`Unable to resolve dependency: <span class="hljs-subst">${specifier}</span>`</span>); 863 } 864 <span class="hljs-keyword">await</span> bar.<span class="hljs-title function_">link</span>(linker); 865 866 <span class="hljs-comment">// Step 3</span> 867 <span class="hljs-comment">//</span> 868 <span class="hljs-comment">// Evaluate the Module. The evaluate() method returns a promise which will</span> 869 <span class="hljs-comment">// resolve after the module has finished evaluating.</span> 870 871 <span class="hljs-comment">// Prints 42.</span> 872 <span class="hljs-keyword">await</span> bar.evaluate(); 873})();</code><button class="copy-button">copy</button></pre> 874<h4><code>module.dependencySpecifiers</code><span><a class="mark" href="#moduledependencyspecifiers" id="moduledependencyspecifiers">#</a></span><a aria-hidden="true" class="legacy" id="vm_module_dependencyspecifiers"></a></h4> 875<ul> 876<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string[]></a></li> 877</ul> 878<p>The specifiers of all dependencies of this module. The returned array is frozen 879to disallow any changes to it.</p> 880<p>Corresponds to the <code>[[RequestedModules]]</code> field of <a href="https://tc39.es/ecma262/#sec-cyclic-module-records">Cyclic Module Record</a>s in 881the ECMAScript specification.</p> 882<h4><code>module.error</code><span><a class="mark" href="#moduleerror" id="moduleerror">#</a></span><a aria-hidden="true" class="legacy" id="vm_module_error"></a></h4> 883<ul> 884<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type"><any></a></li> 885</ul> 886<p>If the <code>module.status</code> is <code>'errored'</code>, this property contains the exception 887thrown by the module during evaluation. If the status is anything else, 888accessing this property will result in a thrown exception.</p> 889<p>The value <code>undefined</code> cannot be used for cases where there is not a thrown 890exception due to possible ambiguity with <code>throw undefined;</code>.</p> 891<p>Corresponds to the <code>[[EvaluationError]]</code> field of <a href="https://tc39.es/ecma262/#sec-cyclic-module-records">Cyclic Module Record</a>s 892in the ECMAScript specification.</p> 893<h4><code>module.evaluate([options])</code><span><a class="mark" href="#moduleevaluateoptions" id="moduleevaluateoptions">#</a></span><a aria-hidden="true" class="legacy" id="vm_module_evaluate_options"></a></h4> 894<ul> 895<li><code>options</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a> 896<ul> 897<li><code>timeout</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Specifies the number of milliseconds to evaluate 898before terminating execution. If execution is interrupted, an <a href="errors.html#class-error"><code>Error</code></a> 899will be thrown. This value must be a strictly positive integer.</li> 900<li><code>breakOnSigint</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type"><boolean></a> If <code>true</code>, receiving <code>SIGINT</code> 901(<kbd>Ctrl</kbd>+<kbd>C</kbd>) will terminate execution and throw an 902<a href="errors.html#class-error"><code>Error</code></a>. Existing handlers for the event that have been attached via 903<code>process.on('SIGINT')</code> are disabled during script execution, but continue to 904work after that. <strong>Default:</strong> <code>false</code>.</li> 905</ul> 906</li> 907<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise" class="type"><Promise></a> Fulfills with <code>undefined</code> upon success.</li> 908</ul> 909<p>Evaluate the module.</p> 910<p>This must be called after the module has been linked; otherwise it will reject. 911It could be called also when the module has already been evaluated, in which 912case it will either do nothing if the initial evaluation ended in success 913(<code>module.status</code> is <code>'evaluated'</code>) or it will re-throw the exception that the 914initial evaluation resulted in (<code>module.status</code> is <code>'errored'</code>).</p> 915<p>This method cannot be called while the module is being evaluated 916(<code>module.status</code> is <code>'evaluating'</code>).</p> 917<p>Corresponds to the <a href="https://tc39.es/ecma262/#sec-moduleevaluation">Evaluate() concrete method</a> field of <a href="https://tc39.es/ecma262/#sec-cyclic-module-records">Cyclic Module 918Record</a>s in the ECMAScript specification.</p> 919<h4><code>module.identifier</code><span><a class="mark" href="#moduleidentifier" id="moduleidentifier">#</a></span><a aria-hidden="true" class="legacy" id="vm_module_identifier"></a></h4> 920<ul> 921<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a></li> 922</ul> 923<p>The identifier of the current module, as set in the constructor.</p> 924<h4><code>module.link(linker)</code><span><a class="mark" href="#modulelinklinker" id="modulelinklinker">#</a></span><a aria-hidden="true" class="legacy" id="vm_module_link_linker"></a></h4> 925<div class="api_metadata"> 926<details class="changelog"><summary>History</summary> 927<table> 928<tbody><tr><th>Version</th><th>Changes</th></tr> 929<tr><td>v18.19.0</td> 930<td><p>The option <code>extra.assert</code> is renamed to <code>extra.attributes</code>. The former name is still provided for backward compatibility.</p></td></tr> 931</tbody></table> 932</details> 933</div> 934<ul> 935<li><code>linker</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function" class="type"><Function></a> 936<ul> 937<li> 938<p><code>specifier</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> The specifier of the requested module:</p> 939<pre><code class="language-js mjs"><span class="hljs-keyword">import</span> foo <span class="hljs-keyword">from</span> <span class="hljs-string">'foo'</span>; 940<span class="hljs-comment">// ^^^^^ the module specifier</span></code> <button class="copy-button">copy</button></pre> 941</li> 942<li> 943<p><code>referencingModule</code> <a href="vm.html#class-vmmodule" class="type"><vm.Module></a> The <code>Module</code> object <code>link()</code> is called on.</p> 944</li> 945<li> 946<p><code>extra</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a></p> 947<ul> 948<li><code>attributes</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a> The data from the attribute: 949<pre><code class="language-js mjs"><span class="hljs-keyword">import</span> foo <span class="hljs-keyword">from</span> <span class="hljs-string">'foo'</span> <span class="hljs-keyword">with</span> { <span class="hljs-attr">name</span>: <span class="hljs-string">'value'</span> }; 950<span class="hljs-comment">// ^^^^^^^^^^^^^^^^^ the attribute</span></code> <button class="copy-button">copy</button></pre> 951Per ECMA-262, hosts are expected to trigger an error if an 952unsupported attribute is present.</li> 953<li><code>assert</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a> Alias for <code>extra.attributes</code>.</li> 954</ul> 955</li> 956<li> 957<p>Returns: <a href="vm.html#class-vmmodule" class="type"><vm.Module></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise" class="type"><Promise></a></p> 958</li> 959</ul> 960</li> 961<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise" class="type"><Promise></a></li> 962</ul> 963<p>Link module dependencies. This method must be called before evaluation, and 964can only be called once per module.</p> 965<p>The function is expected to return a <code>Module</code> object or a <code>Promise</code> that 966eventually resolves to a <code>Module</code> object. The returned <code>Module</code> must satisfy the 967following two invariants:</p> 968<ul> 969<li>It must belong to the same context as the parent <code>Module</code>.</li> 970<li>Its <code>status</code> must not be <code>'errored'</code>.</li> 971</ul> 972<p>If the returned <code>Module</code>'s <code>status</code> is <code>'unlinked'</code>, this method will be 973recursively called on the returned <code>Module</code> with the same provided <code>linker</code> 974function.</p> 975<p><code>link()</code> returns a <code>Promise</code> that will either get resolved when all linking 976instances resolve to a valid <code>Module</code>, or rejected if the linker function either 977throws an exception or returns an invalid <code>Module</code>.</p> 978<p>The linker function roughly corresponds to the implementation-defined 979<a href="https://tc39.es/ecma262/#sec-hostresolveimportedmodule">HostResolveImportedModule</a> abstract operation in the ECMAScript 980specification, with a few key differences:</p> 981<ul> 982<li>The linker function is allowed to be asynchronous while 983<a href="https://tc39.es/ecma262/#sec-hostresolveimportedmodule">HostResolveImportedModule</a> is synchronous.</li> 984</ul> 985<p>The actual <a href="https://tc39.es/ecma262/#sec-hostresolveimportedmodule">HostResolveImportedModule</a> implementation used during module 986linking is one that returns the modules linked during linking. Since at 987that point all modules would have been fully linked already, the 988<a href="https://tc39.es/ecma262/#sec-hostresolveimportedmodule">HostResolveImportedModule</a> implementation is fully synchronous per 989specification.</p> 990<p>Corresponds to the <a href="https://tc39.es/ecma262/#sec-moduledeclarationlinking">Link() concrete method</a> field of <a href="https://tc39.es/ecma262/#sec-cyclic-module-records">Cyclic Module 991Record</a>s in the ECMAScript specification.</p> 992<h4><code>module.namespace</code><span><a class="mark" href="#modulenamespace" id="modulenamespace">#</a></span><a aria-hidden="true" class="legacy" id="vm_module_namespace"></a></h4> 993<ul> 994<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a></li> 995</ul> 996<p>The namespace object of the module. This is only available after linking 997(<code>module.link()</code>) has completed.</p> 998<p>Corresponds to the <a href="https://tc39.es/ecma262/#sec-getmodulenamespace">GetModuleNamespace</a> abstract operation in the ECMAScript 999specification.</p> 1000<h4><code>module.status</code><span><a class="mark" href="#modulestatus" id="modulestatus">#</a></span><a aria-hidden="true" class="legacy" id="vm_module_status"></a></h4> 1001<ul> 1002<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a></li> 1003</ul> 1004<p>The current status of the module. Will be one of:</p> 1005<ul> 1006<li> 1007<p><code>'unlinked'</code>: <code>module.link()</code> has not yet been called.</p> 1008</li> 1009<li> 1010<p><code>'linking'</code>: <code>module.link()</code> has been called, but not all Promises returned 1011by the linker function have been resolved yet.</p> 1012</li> 1013<li> 1014<p><code>'linked'</code>: The module has been linked successfully, and all of its 1015dependencies are linked, but <code>module.evaluate()</code> has not yet been called.</p> 1016</li> 1017<li> 1018<p><code>'evaluating'</code>: The module is being evaluated through a <code>module.evaluate()</code> on 1019itself or a parent module.</p> 1020</li> 1021<li> 1022<p><code>'evaluated'</code>: The module has been successfully evaluated.</p> 1023</li> 1024<li> 1025<p><code>'errored'</code>: The module has been evaluated, but an exception was thrown.</p> 1026</li> 1027</ul> 1028<p>Other than <code>'errored'</code>, this status string corresponds to the specification's 1029<a href="https://tc39.es/ecma262/#sec-cyclic-module-records">Cyclic Module Record</a>'s <code>[[Status]]</code> field. <code>'errored'</code> corresponds to 1030<code>'evaluated'</code> in the specification, but with <code>[[EvaluationError]]</code> set to a 1031value that is not <code>undefined</code>.</p> 1032</section><section><h3>Class: <code>vm.SourceTextModule</code><span><a class="mark" href="#class-vmsourcetextmodule" id="class-vmsourcetextmodule">#</a></span><a aria-hidden="true" class="legacy" id="vm_class_vm_sourcetextmodule"></a></h3> 1033<div class="api_metadata"> 1034<span>Added in: v9.6.0</span> 1035</div> 1036<p></p><div class="api_stability api_stability_1"><a href="documentation.html#stability-index">Stability: 1</a> - Experimental</div><p></p> 1037<p>This feature is only available with the <code>--experimental-vm-modules</code> command 1038flag enabled.</p> 1039<ul> 1040<li>Extends: <a href="vm.html#class-vmmodule" class="type"><vm.Module></a></li> 1041</ul> 1042<p>The <code>vm.SourceTextModule</code> class provides the <a href="https://tc39.es/ecma262/#sec-source-text-module-records">Source Text Module Record</a> as 1043defined in the ECMAScript specification.</p> 1044<h4><code>new vm.SourceTextModule(code[, options])</code><span><a class="mark" href="#new-vmsourcetextmodulecode-options" id="new-vmsourcetextmodulecode-options">#</a></span><a aria-hidden="true" class="legacy" id="vm_new_vm_sourcetextmodule_code_options"></a></h4> 1045<div class="api_metadata"> 1046<details class="changelog"><summary>History</summary> 1047<table> 1048<tbody><tr><th>Version</th><th>Changes</th></tr> 1049<tr><td>v17.0.0, v16.12.0</td> 1050<td><p>Added support for import attributes to the <code>importModuleDynamically</code> parameter.</p></td></tr> 1051</tbody></table> 1052</details> 1053</div> 1054<ul> 1055<li><code>code</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> JavaScript Module code to parse</li> 1056<li><code>options</code> 1057<ul> 1058<li><code>identifier</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> String used in stack traces. 1059<strong>Default:</strong> <code>'vm:module(i)'</code> where <code>i</code> is a context-specific ascending 1060index.</li> 1061<li><code>cachedData</code> <a href="buffer.html#class-buffer" class="type"><Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type"><TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type"><DataView></a> Provides an optional <code>Buffer</code> or 1062<code>TypedArray</code>, or <code>DataView</code> with V8's code cache data for the supplied 1063source. The <code>code</code> must be the same as the module from which this 1064<code>cachedData</code> was created.</li> 1065<li><code>context</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a> The <a href="#what-does-it-mean-to-contextify-an-object">contextified</a> object as returned by the 1066<code>vm.createContext()</code> method, to compile and evaluate this <code>Module</code> in. 1067If no context is specified, the module is evaluated in the current 1068execution context.</li> 1069<li><code>lineOffset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Specifies the line number offset that is displayed 1070in stack traces produced by this <code>Module</code>. <strong>Default:</strong> <code>0</code>.</li> 1071<li><code>columnOffset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Specifies the first-line column number offset that 1072is displayed in stack traces produced by this <code>Module</code>. <strong>Default:</strong> <code>0</code>.</li> 1073<li><code>initializeImportMeta</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function" class="type"><Function></a> Called during evaluation of this <code>Module</code> 1074to initialize the <code>import.meta</code>. 1075<ul> 1076<li><code>meta</code> <a href="esm.html#importmeta" class="type"><import.meta></a></li> 1077<li><code>module</code> <a href="vm.html#class-vmsourcetextmodule" class="type"><vm.SourceTextModule></a></li> 1078</ul> 1079</li> 1080<li><code>importModuleDynamically</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function" class="type"><Function></a> Called during evaluation of this module 1081when <code>import()</code> is called. If this option is not specified, calls to 1082<code>import()</code> will reject with <a href="errors.html#err_vm_dynamic_import_callback_missing"><code>ERR_VM_DYNAMIC_IMPORT_CALLBACK_MISSING</code></a>. 1083If <code>--experimental-vm-modules</code> isn't set, this callback will be ignored 1084and calls to <code>import()</code> will reject with 1085<a href="errors.html#err_vm_dynamic_import_callback_missing_flag"><code>ERR_VM_DYNAMIC_IMPORT_CALLBACK_MISSING_FLAG</code></a>. 1086<ul> 1087<li><code>specifier</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> specifier passed to <code>import()</code></li> 1088<li><code>module</code> <a href="vm.html#class-vmmodule" class="type"><vm.Module></a></li> 1089<li><code>importAttributes</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a> The <code>"assert"</code> value passed to the 1090<a href="https://tc39.es/proposal-import-attributes/#sec-evaluate-import-call"><code>optionsExpression</code></a> optional parameter, or an empty object if no value 1091was provided.</li> 1092<li>Returns: <a href="https://tc39.github.io/ecma262/#sec-module-namespace-exotic-objects" class="type"><Module Namespace Object></a> | <a href="vm.html#class-vmmodule" class="type"><vm.Module></a> Returning a <code>vm.Module</code> is 1093recommended in order to take advantage of error tracking, and to avoid 1094issues with namespaces that contain <code>then</code> function exports.</li> 1095</ul> 1096</li> 1097</ul> 1098</li> 1099</ul> 1100<p>Creates a new <code>SourceTextModule</code> instance.</p> 1101<p>Properties assigned to the <code>import.meta</code> object that are objects may 1102allow the module to access information outside the specified <code>context</code>. Use 1103<code>vm.runInContext()</code> to create objects in a specific context.</p> 1104 1105<pre class="with-60-chars"><input class="js-flavor-selector" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> vm <span class="hljs-keyword">from</span> <span class="hljs-string">'node:vm'</span>; 1106 1107<span class="hljs-keyword">const</span> contextifiedObject = vm.<span class="hljs-title function_">createContext</span>({ <span class="hljs-attr">secret</span>: <span class="hljs-number">42</span> }); 1108 1109<span class="hljs-keyword">const</span> <span class="hljs-variable language_">module</span> = <span class="hljs-keyword">new</span> vm.<span class="hljs-title class_">SourceTextModule</span>( 1110 <span class="hljs-string">'Object.getPrototypeOf(import.meta.prop).secret = secret;'</span>, 1111 { 1112 <span class="hljs-title function_">initializeImportMeta</span>(<span class="hljs-params">meta</span>) { 1113 <span class="hljs-comment">// Note: this object is created in the top context. As such,</span> 1114 <span class="hljs-comment">// Object.getPrototypeOf(import.meta.prop) points to the</span> 1115 <span class="hljs-comment">// Object.prototype in the top context rather than that in</span> 1116 <span class="hljs-comment">// the contextified object.</span> 1117 meta.<span class="hljs-property">prop</span> = {}; 1118 }, 1119 }); 1120<span class="hljs-comment">// Since module has no dependencies, the linker function will never be called.</span> 1121<span class="hljs-keyword">await</span> <span class="hljs-variable language_">module</span>.<span class="hljs-title function_">link</span>(<span class="hljs-function">() =></span> {}); 1122<span class="hljs-keyword">await</span> <span class="hljs-variable language_">module</span>.evaluate(); 1123 1124<span class="hljs-comment">// Now, Object.prototype.secret will be equal to 42.</span> 1125<span class="hljs-comment">//</span> 1126<span class="hljs-comment">// To fix this problem, replace</span> 1127<span class="hljs-comment">// meta.prop = {};</span> 1128<span class="hljs-comment">// above with</span> 1129<span class="hljs-comment">// meta.prop = vm.runInContext('{}', contextifiedObject);</span></code><code class="language-js cjs"><span class="hljs-keyword">const</span> vm = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:vm'</span>); 1130<span class="hljs-keyword">const</span> contextifiedObject = vm.<span class="hljs-title function_">createContext</span>({ <span class="hljs-attr">secret</span>: <span class="hljs-number">42</span> }); 1131(<span class="hljs-keyword">async</span> () => { 1132 <span class="hljs-keyword">const</span> <span class="hljs-variable language_">module</span> = <span class="hljs-keyword">new</span> vm.<span class="hljs-title class_">SourceTextModule</span>( 1133 <span class="hljs-string">'Object.getPrototypeOf(import.meta.prop).secret = secret;'</span>, 1134 { 1135 <span class="hljs-title function_">initializeImportMeta</span>(<span class="hljs-params">meta</span>) { 1136 <span class="hljs-comment">// Note: this object is created in the top context. As such,</span> 1137 <span class="hljs-comment">// Object.getPrototypeOf(import.meta.prop) points to the</span> 1138 <span class="hljs-comment">// Object.prototype in the top context rather than that in</span> 1139 <span class="hljs-comment">// the contextified object.</span> 1140 meta.<span class="hljs-property">prop</span> = {}; 1141 }, 1142 }); 1143 <span class="hljs-comment">// Since module has no dependencies, the linker function will never be called.</span> 1144 <span class="hljs-keyword">await</span> <span class="hljs-variable language_">module</span>.<span class="hljs-title function_">link</span>(<span class="hljs-function">() =></span> {}); 1145 <span class="hljs-keyword">await</span> <span class="hljs-variable language_">module</span>.evaluate(); 1146 <span class="hljs-comment">// Now, Object.prototype.secret will be equal to 42.</span> 1147 <span class="hljs-comment">//</span> 1148 <span class="hljs-comment">// To fix this problem, replace</span> 1149 <span class="hljs-comment">// meta.prop = {};</span> 1150 <span class="hljs-comment">// above with</span> 1151 <span class="hljs-comment">// meta.prop = vm.runInContext('{}', contextifiedObject);</span> 1152})();</code><button class="copy-button">copy</button></pre> 1153<h4><code>sourceTextModule.createCachedData()</code><span><a class="mark" href="#sourcetextmodulecreatecacheddata" id="sourcetextmodulecreatecacheddata">#</a></span><a aria-hidden="true" class="legacy" id="vm_sourcetextmodule_createcacheddata"></a></h4> 1154<div class="api_metadata"> 1155<span>Added in: v13.7.0, v12.17.0</span> 1156</div> 1157<ul> 1158<li>Returns: <a href="buffer.html#class-buffer" class="type"><Buffer></a></li> 1159</ul> 1160<p>Creates a code cache that can be used with the <code>SourceTextModule</code> constructor's 1161<code>cachedData</code> option. Returns a <code>Buffer</code>. This method may be called any number 1162of times before the module has been evaluated.</p> 1163<p>The code cache of the <code>SourceTextModule</code> doesn't contain any JavaScript 1164observable states. The code cache is safe to be saved along side the script 1165source and used to construct new <code>SourceTextModule</code> instances multiple times.</p> 1166<p>Functions in the <code>SourceTextModule</code> source can be marked as lazily compiled 1167and they are not compiled at construction of the <code>SourceTextModule</code>. These 1168functions are going to be compiled when they are invoked the first time. The 1169code cache serializes the metadata that V8 currently knows about the 1170<code>SourceTextModule</code> that it can use to speed up future compilations.</p> 1171<pre><code class="language-js"><span class="hljs-comment">// Create an initial module</span> 1172<span class="hljs-keyword">const</span> <span class="hljs-variable language_">module</span> = <span class="hljs-keyword">new</span> vm.<span class="hljs-title class_">SourceTextModule</span>(<span class="hljs-string">'const a = 1;'</span>); 1173 1174<span class="hljs-comment">// Create cached data from this module</span> 1175<span class="hljs-keyword">const</span> cachedData = <span class="hljs-variable language_">module</span>.<span class="hljs-title function_">createCachedData</span>(); 1176 1177<span class="hljs-comment">// Create a new module using the cached data. The code must be the same.</span> 1178<span class="hljs-keyword">const</span> module2 = <span class="hljs-keyword">new</span> vm.<span class="hljs-title class_">SourceTextModule</span>(<span class="hljs-string">'const a = 1;'</span>, { cachedData });</code> <button class="copy-button">copy</button></pre> 1179</section><section><h3>Class: <code>vm.SyntheticModule</code><span><a class="mark" href="#class-vmsyntheticmodule" id="class-vmsyntheticmodule">#</a></span><a aria-hidden="true" class="legacy" id="vm_class_vm_syntheticmodule"></a></h3> 1180<div class="api_metadata"> 1181<span>Added in: v13.0.0, v12.16.0</span> 1182</div> 1183<p></p><div class="api_stability api_stability_1"><a href="documentation.html#stability-index">Stability: 1</a> - Experimental</div><p></p> 1184<p>This feature is only available with the <code>--experimental-vm-modules</code> command 1185flag enabled.</p> 1186<ul> 1187<li>Extends: <a href="vm.html#class-vmmodule" class="type"><vm.Module></a></li> 1188</ul> 1189<p>The <code>vm.SyntheticModule</code> class provides the <a href="https://heycam.github.io/webidl/#synthetic-module-records">Synthetic Module Record</a> as 1190defined in the WebIDL specification. The purpose of synthetic modules is to 1191provide a generic interface for exposing non-JavaScript sources to ECMAScript 1192module graphs.</p> 1193<pre><code class="language-js"><span class="hljs-keyword">const</span> vm = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:vm'</span>); 1194 1195<span class="hljs-keyword">const</span> source = <span class="hljs-string">'{ "a": 1 }'</span>; 1196<span class="hljs-keyword">const</span> <span class="hljs-variable language_">module</span> = <span class="hljs-keyword">new</span> vm.<span class="hljs-title class_">SyntheticModule</span>([<span class="hljs-string">'default'</span>], <span class="hljs-keyword">function</span>(<span class="hljs-params"></span>) { 1197 <span class="hljs-keyword">const</span> obj = <span class="hljs-title class_">JSON</span>.<span class="hljs-title function_">parse</span>(source); 1198 <span class="hljs-variable language_">this</span>.<span class="hljs-title function_">setExport</span>(<span class="hljs-string">'default'</span>, obj); 1199}); 1200 1201<span class="hljs-comment">// Use `module` in linking...</span></code> <button class="copy-button">copy</button></pre> 1202<h4><code>new vm.SyntheticModule(exportNames, evaluateCallback[, options])</code><span><a class="mark" href="#new-vmsyntheticmoduleexportnames-evaluatecallback-options" id="new-vmsyntheticmoduleexportnames-evaluatecallback-options">#</a></span><a aria-hidden="true" class="legacy" id="vm_new_vm_syntheticmodule_exportnames_evaluatecallback_options"></a></h4> 1203<div class="api_metadata"> 1204<span>Added in: v13.0.0, v12.16.0</span> 1205</div> 1206<ul> 1207<li><code>exportNames</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string[]></a> Array of names that will be exported from the 1208module.</li> 1209<li><code>evaluateCallback</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function" class="type"><Function></a> Called when the module is evaluated.</li> 1210<li><code>options</code> 1211<ul> 1212<li><code>identifier</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> String used in stack traces. 1213<strong>Default:</strong> <code>'vm:module(i)'</code> where <code>i</code> is a context-specific ascending 1214index.</li> 1215<li><code>context</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a> The <a href="#what-does-it-mean-to-contextify-an-object">contextified</a> object as returned by the 1216<code>vm.createContext()</code> method, to compile and evaluate this <code>Module</code> in.</li> 1217</ul> 1218</li> 1219</ul> 1220<p>Creates a new <code>SyntheticModule</code> instance.</p> 1221<p>Objects assigned to the exports of this instance may allow importers of 1222the module to access information outside the specified <code>context</code>. Use 1223<code>vm.runInContext()</code> to create objects in a specific context.</p> 1224<h4><code>syntheticModule.setExport(name, value)</code><span><a class="mark" href="#syntheticmodulesetexportname-value" id="syntheticmodulesetexportname-value">#</a></span><a aria-hidden="true" class="legacy" id="vm_syntheticmodule_setexport_name_value"></a></h4> 1225<div class="api_metadata"> 1226<span>Added in: v13.0.0, v12.16.0</span> 1227</div> 1228<ul> 1229<li><code>name</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> Name of the export to set.</li> 1230<li><code>value</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type"><any></a> The value to set the export to.</li> 1231</ul> 1232<p>This method is used after the module is linked to set the values of exports. If 1233it is called before the module is linked, an <a href="errors.html#err_vm_module_status"><code>ERR_VM_MODULE_STATUS</code></a> error 1234will be thrown.</p> 1235 1236<pre class="with-30-chars"><input class="js-flavor-selector" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> vm <span class="hljs-keyword">from</span> <span class="hljs-string">'node:vm'</span>; 1237 1238<span class="hljs-keyword">const</span> m = <span class="hljs-keyword">new</span> vm.<span class="hljs-title class_">SyntheticModule</span>([<span class="hljs-string">'x'</span>], <span class="hljs-function">() =></span> { 1239 m.<span class="hljs-title function_">setExport</span>(<span class="hljs-string">'x'</span>, <span class="hljs-number">1</span>); 1240}); 1241 1242<span class="hljs-keyword">await</span> m.<span class="hljs-title function_">link</span>(<span class="hljs-function">() =></span> {}); 1243<span class="hljs-keyword">await</span> m.evaluate(); 1244 1245assert.<span class="hljs-title function_">strictEqual</span>(m.<span class="hljs-property">namespace</span>.<span class="hljs-property">x</span>, <span class="hljs-number">1</span>);</code><code class="language-js cjs"><span class="hljs-keyword">const</span> vm = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:vm'</span>); 1246(<span class="hljs-keyword">async</span> () => { 1247 <span class="hljs-keyword">const</span> m = <span class="hljs-keyword">new</span> vm.<span class="hljs-title class_">SyntheticModule</span>([<span class="hljs-string">'x'</span>], <span class="hljs-function">() =></span> { 1248 m.<span class="hljs-title function_">setExport</span>(<span class="hljs-string">'x'</span>, <span class="hljs-number">1</span>); 1249 }); 1250 <span class="hljs-keyword">await</span> m.<span class="hljs-title function_">link</span>(<span class="hljs-function">() =></span> {}); 1251 <span class="hljs-keyword">await</span> m.evaluate(); 1252 assert.<span class="hljs-title function_">strictEqual</span>(m.<span class="hljs-property">namespace</span>.<span class="hljs-property">x</span>, <span class="hljs-number">1</span>); 1253})();</code><button class="copy-button">copy</button></pre> 1254</section><section><h3><code>vm.compileFunction(code[, params[, options]])</code><span><a class="mark" href="#vmcompilefunctioncode-params-options" id="vmcompilefunctioncode-params-options">#</a></span><a aria-hidden="true" class="legacy" id="vm_vm_compilefunction_code_params_options"></a></h3> 1255<div class="api_metadata"> 1256<details class="changelog"><summary>History</summary> 1257<table> 1258<tbody><tr><th>Version</th><th>Changes</th></tr> 1259<tr><td>v18.15.0</td> 1260<td><p>The return value now includes <code>cachedDataRejected</code> with the same semantics as the <code>vm.Script</code> version if the <code>cachedData</code> option was passed.</p></td></tr> 1261<tr><td>v17.0.0, v16.12.0</td> 1262<td><p>Added support for import attributes to the <code>importModuleDynamically</code> parameter.</p></td></tr> 1263<tr><td>v15.9.0</td> 1264<td><p>Added <code>importModuleDynamically</code> option again.</p></td></tr> 1265<tr><td>v14.3.0</td> 1266<td><p>Removal of <code>importModuleDynamically</code> due to compatibility issues.</p></td></tr> 1267<tr><td>v14.1.0, v13.14.0</td> 1268<td><p>The <code>importModuleDynamically</code> option is now supported.</p></td></tr> 1269<tr><td>v10.10.0</td> 1270<td><p><span>Added in: v10.10.0</span></p></td></tr> 1271</tbody></table> 1272</details> 1273</div> 1274<ul> 1275<li><code>code</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> The body of the function to compile.</li> 1276<li><code>params</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string[]></a> An array of strings containing all parameters for the 1277function.</li> 1278<li><code>options</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a> 1279<ul> 1280<li><code>filename</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> Specifies the filename used in stack traces produced 1281by this script. <strong>Default:</strong> <code>''</code>.</li> 1282<li><code>lineOffset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><number></a> Specifies the line number offset that is displayed 1283in stack traces produced by this script. <strong>Default:</strong> <code>0</code>.</li> 1284<li><code>columnOffset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><number></a> Specifies the first-line column number offset that 1285is displayed in stack traces produced by this script. <strong>Default:</strong> <code>0</code>.</li> 1286<li><code>cachedData</code> <a href="buffer.html#class-buffer" class="type"><Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type"><TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type"><DataView></a> Provides an optional <code>Buffer</code> or 1287<code>TypedArray</code>, or <code>DataView</code> with V8's code cache data for the supplied 1288source. This must be produced by a prior call to <a href="#vmcompilefunctioncode-params-options"><code>vm.compileFunction()</code></a> 1289with the same <code>code</code> and <code>params</code>.</li> 1290<li><code>produceCachedData</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type"><boolean></a> Specifies whether to produce new cache data. 1291<strong>Default:</strong> <code>false</code>.</li> 1292<li><code>parsingContext</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a> The <a href="#what-does-it-mean-to-contextify-an-object">contextified</a> object in which the said 1293function should be compiled in.</li> 1294<li><code>contextExtensions</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object[]></a> An array containing a collection of context 1295extensions (objects wrapping the current scope) to be applied while 1296compiling. <strong>Default:</strong> <code>[]</code>.</li> 1297<li><code>importModuleDynamically</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function" class="type"><Function></a> Called during evaluation of this module 1298when <code>import()</code> is called. If this option is not specified, calls to 1299<code>import()</code> will reject with <a href="errors.html#err_vm_dynamic_import_callback_missing"><code>ERR_VM_DYNAMIC_IMPORT_CALLBACK_MISSING</code></a>. 1300This option is part of the experimental modules API, and should not be 1301considered stable. If <code>--experimental-vm-modules</code> isn't 1302set, this callback will be ignored and calls to <code>import()</code> will reject with 1303<a href="errors.html#err_vm_dynamic_import_callback_missing_flag"><code>ERR_VM_DYNAMIC_IMPORT_CALLBACK_MISSING_FLAG</code></a>. 1304<ul> 1305<li><code>specifier</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> specifier passed to <code>import()</code></li> 1306<li><code>function</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function" class="type"><Function></a></li> 1307<li><code>importAttributes</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a> The <code>"with"</code> value passed to the 1308<a href="https://tc39.es/proposal-import-attributes/#sec-evaluate-import-call"><code>optionsExpression</code></a> optional parameter, or an empty object if no value 1309was provided.</li> 1310<li>Returns: <a href="https://tc39.github.io/ecma262/#sec-module-namespace-exotic-objects" class="type"><Module Namespace Object></a> | <a href="vm.html#class-vmmodule" class="type"><vm.Module></a> Returning a <code>vm.Module</code> is 1311recommended in order to take advantage of error tracking, and to avoid 1312issues with namespaces that contain <code>then</code> function exports.</li> 1313</ul> 1314</li> 1315</ul> 1316</li> 1317<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function" class="type"><Function></a></li> 1318</ul> 1319<p>Compiles the given code into the provided context (if no context is 1320supplied, the current context is used), and returns it wrapped inside a 1321function with the given <code>params</code>.</p> 1322</section><section><h3><code>vm.createContext([contextObject[, options]])</code><span><a class="mark" href="#vmcreatecontextcontextobject-options" id="vmcreatecontextcontextobject-options">#</a></span><a aria-hidden="true" class="legacy" id="vm_vm_createcontext_contextobject_options"></a></h3> 1323<div class="api_metadata"> 1324<details class="changelog"><summary>History</summary> 1325<table> 1326<tbody><tr><th>Version</th><th>Changes</th></tr> 1327<tr><td>v14.6.0</td> 1328<td><p>The <code>microtaskMode</code> option is supported now.</p></td></tr> 1329<tr><td>v10.0.0</td> 1330<td><p>The first argument can no longer be a function.</p></td></tr> 1331<tr><td>v10.0.0</td> 1332<td><p>The <code>codeGeneration</code> option is supported now.</p></td></tr> 1333<tr><td>v0.3.1</td> 1334<td><p><span>Added in: v0.3.1</span></p></td></tr> 1335</tbody></table> 1336</details> 1337</div> 1338<ul> 1339<li><code>contextObject</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a></li> 1340<li><code>options</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a> 1341<ul> 1342<li><code>name</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> Human-readable name of the newly created context. 1343<strong>Default:</strong> <code>'VM Context i'</code>, where <code>i</code> is an ascending numerical index of 1344the created context.</li> 1345<li><code>origin</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> <a href="https://developer.mozilla.org/en-US/docs/Glossary/Origin">Origin</a> corresponding to the newly created 1346context for display purposes. The origin should be formatted like a URL, 1347but with only the scheme, host, and port (if necessary), like the value of 1348the <a href="url.html#urlorigin"><code>url.origin</code></a> property of a <a href="url.html#class-url"><code>URL</code></a> object. Most notably, this 1349string should omit the trailing slash, as that denotes a path. 1350<strong>Default:</strong> <code>''</code>.</li> 1351<li><code>codeGeneration</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a> 1352<ul> 1353<li><code>strings</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type"><boolean></a> If set to false any calls to <code>eval</code> or function 1354constructors (<code>Function</code>, <code>GeneratorFunction</code>, etc) will throw an 1355<code>EvalError</code>. <strong>Default:</strong> <code>true</code>.</li> 1356<li><code>wasm</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type"><boolean></a> If set to false any attempt to compile a WebAssembly 1357module will throw a <code>WebAssembly.CompileError</code>. <strong>Default:</strong> <code>true</code>.</li> 1358</ul> 1359</li> 1360<li><code>microtaskMode</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> If set to <code>afterEvaluate</code>, microtasks (tasks 1361scheduled through <code>Promise</code>s and <code>async function</code>s) will be run immediately 1362after a script has run through <a href="#scriptrunincontextcontextifiedobject-options"><code>script.runInContext()</code></a>. 1363They are included in the <code>timeout</code> and <code>breakOnSigint</code> scopes in that case.</li> 1364</ul> 1365</li> 1366<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a> contextified object.</li> 1367</ul> 1368<p>If given a <code>contextObject</code>, the <code>vm.createContext()</code> method will <a href="#what-does-it-mean-to-contextify-an-object">prepare 1369that object</a> so that it can be used in calls to 1370<a href="#vmrunincontextcode-contextifiedobject-options"><code>vm.runInContext()</code></a> or <a href="#scriptrunincontextcontextifiedobject-options"><code>script.runInContext()</code></a>. Inside such scripts, 1371the <code>contextObject</code> will be the global object, retaining all of its existing 1372properties but also having the built-in objects and functions any standard 1373<a href="https://es5.github.io/#x15.1">global object</a> has. Outside of scripts run by the vm module, global variables 1374will remain unchanged.</p> 1375<pre><code class="language-js"><span class="hljs-keyword">const</span> vm = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:vm'</span>); 1376 1377<span class="hljs-variable language_">global</span>.<span class="hljs-property">globalVar</span> = <span class="hljs-number">3</span>; 1378 1379<span class="hljs-keyword">const</span> context = { <span class="hljs-attr">globalVar</span>: <span class="hljs-number">1</span> }; 1380vm.<span class="hljs-title function_">createContext</span>(context); 1381 1382vm.<span class="hljs-title function_">runInContext</span>(<span class="hljs-string">'globalVar *= 2;'</span>, context); 1383 1384<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(context); 1385<span class="hljs-comment">// Prints: { globalVar: 2 }</span> 1386 1387<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-variable language_">global</span>.<span class="hljs-property">globalVar</span>); 1388<span class="hljs-comment">// Prints: 3</span></code> <button class="copy-button">copy</button></pre> 1389<p>If <code>contextObject</code> is omitted (or passed explicitly as <code>undefined</code>), a new, 1390empty <a href="#what-does-it-mean-to-contextify-an-object">contextified</a> object will be returned.</p> 1391<p>The <code>vm.createContext()</code> method is primarily useful for creating a single 1392context that can be used to run multiple scripts. For instance, if emulating a 1393web browser, the method can be used to create a single context representing a 1394window's global object, then run all <code><script></code> tags together within that 1395context.</p> 1396<p>The provided <code>name</code> and <code>origin</code> of the context are made visible through the 1397Inspector API.</p> 1398</section><section><h3><code>vm.isContext(object)</code><span><a class="mark" href="#vmiscontextobject" id="vmiscontextobject">#</a></span><a aria-hidden="true" class="legacy" id="vm_vm_iscontext_object"></a></h3> 1399<div class="api_metadata"> 1400<span>Added in: v0.11.7</span> 1401</div> 1402<ul> 1403<li><code>object</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a></li> 1404<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type"><boolean></a></li> 1405</ul> 1406<p>Returns <code>true</code> if the given <code>object</code> object has been <a href="#what-does-it-mean-to-contextify-an-object">contextified</a> using 1407<a href="#vmcreatecontextcontextobject-options"><code>vm.createContext()</code></a>.</p> 1408</section><section><h3><code>vm.measureMemory([options])</code><span><a class="mark" href="#vmmeasurememoryoptions" id="vmmeasurememoryoptions">#</a></span><a aria-hidden="true" class="legacy" id="vm_vm_measurememory_options"></a></h3> 1409<div class="api_metadata"> 1410<span>Added in: v13.10.0</span> 1411</div> 1412<p></p><div class="api_stability api_stability_1"><a href="documentation.html#stability-index">Stability: 1</a> - Experimental</div><p></p> 1413<p>Measure the memory known to V8 and used by all contexts known to the 1414current V8 isolate, or the main context.</p> 1415<ul> 1416<li><code>options</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a> Optional. 1417<ul> 1418<li><code>mode</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> Either <code>'summary'</code> or <code>'detailed'</code>. In summary mode, 1419only the memory measured for the main context will be returned. In 1420detailed mode, the memory measured for all contexts known to the 1421current V8 isolate will be returned. 1422<strong>Default:</strong> <code>'summary'</code></li> 1423<li><code>execution</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> Either <code>'default'</code> or <code>'eager'</code>. With default 1424execution, the promise will not resolve until after the next scheduled 1425garbage collection starts, which may take a while (or never if the program 1426exits before the next GC). With eager execution, the GC will be started 1427right away to measure the memory. 1428<strong>Default:</strong> <code>'default'</code></li> 1429</ul> 1430</li> 1431<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise" class="type"><Promise></a> If the memory is successfully measured, the promise will 1432resolve with an object containing information about the memory usage. 1433Otherwise it will be rejected with an <code>ERR_CONTEXT_NOT_INITIALIZED</code> error.</li> 1434</ul> 1435<p>The format of the object that the returned Promise may resolve with is 1436specific to the V8 engine and may change from one version of V8 to the next.</p> 1437<p>The returned result is different from the statistics returned by 1438<code>v8.getHeapSpaceStatistics()</code> in that <code>vm.measureMemory()</code> measure the 1439memory reachable by each V8 specific contexts in the current instance of 1440the V8 engine, while the result of <code>v8.getHeapSpaceStatistics()</code> measure 1441the memory occupied by each heap space in the current V8 instance.</p> 1442<pre><code class="language-js"><span class="hljs-keyword">const</span> vm = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:vm'</span>); 1443<span class="hljs-comment">// Measure the memory used by the main context.</span> 1444vm.<span class="hljs-title function_">measureMemory</span>({ <span class="hljs-attr">mode</span>: <span class="hljs-string">'summary'</span> }) 1445 <span class="hljs-comment">// This is the same as vm.measureMemory()</span> 1446 .<span class="hljs-title function_">then</span>(<span class="hljs-function">(<span class="hljs-params">result</span>) =></span> { 1447 <span class="hljs-comment">// The current format is:</span> 1448 <span class="hljs-comment">// {</span> 1449 <span class="hljs-comment">// total: {</span> 1450 <span class="hljs-comment">// jsMemoryEstimate: 2418479, jsMemoryRange: [ 2418479, 2745799 ]</span> 1451 <span class="hljs-comment">// }</span> 1452 <span class="hljs-comment">// }</span> 1453 <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(result); 1454 }); 1455 1456<span class="hljs-keyword">const</span> context = vm.<span class="hljs-title function_">createContext</span>({ <span class="hljs-attr">a</span>: <span class="hljs-number">1</span> }); 1457vm.<span class="hljs-title function_">measureMemory</span>({ <span class="hljs-attr">mode</span>: <span class="hljs-string">'detailed'</span>, <span class="hljs-attr">execution</span>: <span class="hljs-string">'eager'</span> }) 1458 .<span class="hljs-title function_">then</span>(<span class="hljs-function">(<span class="hljs-params">result</span>) =></span> { 1459 <span class="hljs-comment">// Reference the context here so that it won't be GC'ed</span> 1460 <span class="hljs-comment">// until the measurement is complete.</span> 1461 <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(context.<span class="hljs-property">a</span>); 1462 <span class="hljs-comment">// {</span> 1463 <span class="hljs-comment">// total: {</span> 1464 <span class="hljs-comment">// jsMemoryEstimate: 2574732,</span> 1465 <span class="hljs-comment">// jsMemoryRange: [ 2574732, 2904372 ]</span> 1466 <span class="hljs-comment">// },</span> 1467 <span class="hljs-comment">// current: {</span> 1468 <span class="hljs-comment">// jsMemoryEstimate: 2438996,</span> 1469 <span class="hljs-comment">// jsMemoryRange: [ 2438996, 2768636 ]</span> 1470 <span class="hljs-comment">// },</span> 1471 <span class="hljs-comment">// other: [</span> 1472 <span class="hljs-comment">// {</span> 1473 <span class="hljs-comment">// jsMemoryEstimate: 135736,</span> 1474 <span class="hljs-comment">// jsMemoryRange: [ 135736, 465376 ]</span> 1475 <span class="hljs-comment">// }</span> 1476 <span class="hljs-comment">// ]</span> 1477 <span class="hljs-comment">// }</span> 1478 <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(result); 1479 });</code> <button class="copy-button">copy</button></pre> 1480</section><section><h3><code>vm.runInContext(code, contextifiedObject[, options])</code><span><a class="mark" href="#vmrunincontextcode-contextifiedobject-options" id="vmrunincontextcode-contextifiedobject-options">#</a></span><a aria-hidden="true" class="legacy" id="vm_vm_runincontext_code_contextifiedobject_options"></a></h3> 1481<div class="api_metadata"> 1482<details class="changelog"><summary>History</summary> 1483<table> 1484<tbody><tr><th>Version</th><th>Changes</th></tr> 1485<tr><td>v17.0.0, v16.12.0</td> 1486<td><p>Added support for import attributes to the <code>importModuleDynamically</code> parameter.</p></td></tr> 1487<tr><td>v6.3.0</td> 1488<td><p>The <code>breakOnSigint</code> option is supported now.</p></td></tr> 1489<tr><td>v0.3.1</td> 1490<td><p><span>Added in: v0.3.1</span></p></td></tr> 1491</tbody></table> 1492</details> 1493</div> 1494<ul> 1495<li><code>code</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> The JavaScript code to compile and run.</li> 1496<li><code>contextifiedObject</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a> The <a href="#what-does-it-mean-to-contextify-an-object">contextified</a> object that will be used 1497as the <code>global</code> when the <code>code</code> is compiled and run.</li> 1498<li><code>options</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> 1499<ul> 1500<li><code>filename</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> Specifies the filename used in stack traces produced 1501by this script. <strong>Default:</strong> <code>'evalmachine.<anonymous>'</code>.</li> 1502<li><code>lineOffset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><number></a> Specifies the line number offset that is displayed 1503in stack traces produced by this script. <strong>Default:</strong> <code>0</code>.</li> 1504<li><code>columnOffset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><number></a> Specifies the first-line column number offset that 1505is displayed in stack traces produced by this script. <strong>Default:</strong> <code>0</code>.</li> 1506<li><code>displayErrors</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type"><boolean></a> When <code>true</code>, if an <a href="errors.html#class-error"><code>Error</code></a> occurs 1507while compiling the <code>code</code>, the line of code causing the error is attached 1508to the stack trace. <strong>Default:</strong> <code>true</code>.</li> 1509<li><code>timeout</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Specifies the number of milliseconds to execute <code>code</code> 1510before terminating execution. If execution is terminated, an <a href="errors.html#class-error"><code>Error</code></a> 1511will be thrown. This value must be a strictly positive integer.</li> 1512<li><code>breakOnSigint</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type"><boolean></a> If <code>true</code>, receiving <code>SIGINT</code> 1513(<kbd>Ctrl</kbd>+<kbd>C</kbd>) will terminate execution and throw an 1514<a href="errors.html#class-error"><code>Error</code></a>. Existing handlers for the event that have been attached via 1515<code>process.on('SIGINT')</code> are disabled during script execution, but continue to 1516work after that. <strong>Default:</strong> <code>false</code>.</li> 1517<li><code>cachedData</code> <a href="buffer.html#class-buffer" class="type"><Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type"><TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type"><DataView></a> Provides an optional <code>Buffer</code> or 1518<code>TypedArray</code>, or <code>DataView</code> with V8's code cache data for the supplied 1519source.</li> 1520<li><code>importModuleDynamically</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function" class="type"><Function></a> Called during evaluation of this module 1521when <code>import()</code> is called. If this option is not specified, calls to 1522<code>import()</code> will reject with <a href="errors.html#err_vm_dynamic_import_callback_missing"><code>ERR_VM_DYNAMIC_IMPORT_CALLBACK_MISSING</code></a>. 1523This option is part of the experimental modules API. We do not recommend 1524using it in a production environment. If <code>--experimental-vm-modules</code> isn't 1525set, this callback will be ignored and calls to <code>import()</code> will reject with 1526<a href="errors.html#err_vm_dynamic_import_callback_missing_flag"><code>ERR_VM_DYNAMIC_IMPORT_CALLBACK_MISSING_FLAG</code></a>. 1527<ul> 1528<li><code>specifier</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> specifier passed to <code>import()</code></li> 1529<li><code>script</code> <a href="vm.html#class-vmscript" class="type"><vm.Script></a></li> 1530<li><code>importAttributes</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a> The <code>"with"</code> value passed to the 1531<a href="https://tc39.es/proposal-import-attributes/#sec-evaluate-import-call"><code>optionsExpression</code></a> optional parameter, or an empty object if no value 1532was provided.</li> 1533<li>Returns: <a href="https://tc39.github.io/ecma262/#sec-module-namespace-exotic-objects" class="type"><Module Namespace Object></a> | <a href="vm.html#class-vmmodule" class="type"><vm.Module></a> Returning a <code>vm.Module</code> is 1534recommended in order to take advantage of error tracking, and to avoid 1535issues with namespaces that contain <code>then</code> function exports.</li> 1536</ul> 1537</li> 1538</ul> 1539</li> 1540<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type"><any></a> the result of the very last statement executed in the script.</li> 1541</ul> 1542<p>The <code>vm.runInContext()</code> method compiles <code>code</code>, runs it within the context of 1543the <code>contextifiedObject</code>, then returns the result. Running code does not have 1544access to the local scope. The <code>contextifiedObject</code> object <em>must</em> have been 1545previously <a href="#what-does-it-mean-to-contextify-an-object">contextified</a> using the <a href="#vmcreatecontextcontextobject-options"><code>vm.createContext()</code></a> method.</p> 1546<p>If <code>options</code> is a string, then it specifies the filename.</p> 1547<p>The following example compiles and executes different scripts using a single 1548<a href="#what-does-it-mean-to-contextify-an-object">contextified</a> object:</p> 1549<pre><code class="language-js"><span class="hljs-keyword">const</span> vm = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:vm'</span>); 1550 1551<span class="hljs-keyword">const</span> contextObject = { <span class="hljs-attr">globalVar</span>: <span class="hljs-number">1</span> }; 1552vm.<span class="hljs-title function_">createContext</span>(contextObject); 1553 1554<span class="hljs-keyword">for</span> (<span class="hljs-keyword">let</span> i = <span class="hljs-number">0</span>; i < <span class="hljs-number">10</span>; ++i) { 1555 vm.<span class="hljs-title function_">runInContext</span>(<span class="hljs-string">'globalVar *= 2;'</span>, contextObject); 1556} 1557<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(contextObject); 1558<span class="hljs-comment">// Prints: { globalVar: 1024 }</span></code> <button class="copy-button">copy</button></pre> 1559</section><section><h3><code>vm.runInNewContext(code[, contextObject[, options]])</code><span><a class="mark" href="#vmruninnewcontextcode-contextobject-options" id="vmruninnewcontextcode-contextobject-options">#</a></span><a aria-hidden="true" class="legacy" id="vm_vm_runinnewcontext_code_contextobject_options"></a></h3> 1560<div class="api_metadata"> 1561<details class="changelog"><summary>History</summary> 1562<table> 1563<tbody><tr><th>Version</th><th>Changes</th></tr> 1564<tr><td>v17.0.0, v16.12.0</td> 1565<td><p>Added support for import attributes to the <code>importModuleDynamically</code> parameter.</p></td></tr> 1566<tr><td>v14.6.0</td> 1567<td><p>The <code>microtaskMode</code> option is supported now.</p></td></tr> 1568<tr><td>v10.0.0</td> 1569<td><p>The <code>contextCodeGeneration</code> option is supported now.</p></td></tr> 1570<tr><td>v6.3.0</td> 1571<td><p>The <code>breakOnSigint</code> option is supported now.</p></td></tr> 1572<tr><td>v0.3.1</td> 1573<td><p><span>Added in: v0.3.1</span></p></td></tr> 1574</tbody></table> 1575</details> 1576</div> 1577<ul> 1578<li><code>code</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> The JavaScript code to compile and run.</li> 1579<li><code>contextObject</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a> An object that will be <a href="#what-does-it-mean-to-contextify-an-object">contextified</a>. If 1580<code>undefined</code>, a new object will be created.</li> 1581<li><code>options</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> 1582<ul> 1583<li><code>filename</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> Specifies the filename used in stack traces produced 1584by this script. <strong>Default:</strong> <code>'evalmachine.<anonymous>'</code>.</li> 1585<li><code>lineOffset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><number></a> Specifies the line number offset that is displayed 1586in stack traces produced by this script. <strong>Default:</strong> <code>0</code>.</li> 1587<li><code>columnOffset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><number></a> Specifies the first-line column number offset that 1588is displayed in stack traces produced by this script. <strong>Default:</strong> <code>0</code>.</li> 1589<li><code>displayErrors</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type"><boolean></a> When <code>true</code>, if an <a href="errors.html#class-error"><code>Error</code></a> occurs 1590while compiling the <code>code</code>, the line of code causing the error is attached 1591to the stack trace. <strong>Default:</strong> <code>true</code>.</li> 1592<li><code>timeout</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Specifies the number of milliseconds to execute <code>code</code> 1593before terminating execution. If execution is terminated, an <a href="errors.html#class-error"><code>Error</code></a> 1594will be thrown. This value must be a strictly positive integer.</li> 1595<li><code>breakOnSigint</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type"><boolean></a> If <code>true</code>, receiving <code>SIGINT</code> 1596(<kbd>Ctrl</kbd>+<kbd>C</kbd>) will terminate execution and throw an 1597<a href="errors.html#class-error"><code>Error</code></a>. Existing handlers for the event that have been attached via 1598<code>process.on('SIGINT')</code> are disabled during script execution, but continue to 1599work after that. <strong>Default:</strong> <code>false</code>.</li> 1600<li><code>contextName</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> Human-readable name of the newly created context. 1601<strong>Default:</strong> <code>'VM Context i'</code>, where <code>i</code> is an ascending numerical index of 1602the created context.</li> 1603<li><code>contextOrigin</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> <a href="https://developer.mozilla.org/en-US/docs/Glossary/Origin">Origin</a> corresponding to the newly 1604created context for display purposes. The origin should be formatted like a 1605URL, but with only the scheme, host, and port (if necessary), like the 1606value of the <a href="url.html#urlorigin"><code>url.origin</code></a> property of a <a href="url.html#class-url"><code>URL</code></a> object. Most notably, 1607this string should omit the trailing slash, as that denotes a path. 1608<strong>Default:</strong> <code>''</code>.</li> 1609<li><code>contextCodeGeneration</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a> 1610<ul> 1611<li><code>strings</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type"><boolean></a> If set to false any calls to <code>eval</code> or function 1612constructors (<code>Function</code>, <code>GeneratorFunction</code>, etc) will throw an 1613<code>EvalError</code>. <strong>Default:</strong> <code>true</code>.</li> 1614<li><code>wasm</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type"><boolean></a> If set to false any attempt to compile a WebAssembly 1615module will throw a <code>WebAssembly.CompileError</code>. <strong>Default:</strong> <code>true</code>.</li> 1616</ul> 1617</li> 1618<li><code>cachedData</code> <a href="buffer.html#class-buffer" class="type"><Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type"><TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type"><DataView></a> Provides an optional <code>Buffer</code> or 1619<code>TypedArray</code>, or <code>DataView</code> with V8's code cache data for the supplied 1620source.</li> 1621<li><code>importModuleDynamically</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function" class="type"><Function></a> Called during evaluation of this module 1622when <code>import()</code> is called. If this option is not specified, calls to 1623<code>import()</code> will reject with <a href="errors.html#err_vm_dynamic_import_callback_missing"><code>ERR_VM_DYNAMIC_IMPORT_CALLBACK_MISSING</code></a>. 1624This option is part of the experimental modules API. We do not recommend 1625using it in a production environment. If <code>--experimental-vm-modules</code> isn't 1626set, this callback will be ignored and calls to <code>import()</code> will reject with 1627<a href="errors.html#err_vm_dynamic_import_callback_missing_flag"><code>ERR_VM_DYNAMIC_IMPORT_CALLBACK_MISSING_FLAG</code></a>. 1628<ul> 1629<li><code>specifier</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> specifier passed to <code>import()</code></li> 1630<li><code>script</code> <a href="vm.html#class-vmscript" class="type"><vm.Script></a></li> 1631<li><code>importAttributes</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a> The <code>"with"</code> value passed to the 1632<a href="https://tc39.es/proposal-import-attributes/#sec-evaluate-import-call"><code>optionsExpression</code></a> optional parameter, or an empty object if no value 1633was provided.</li> 1634<li>Returns: <a href="https://tc39.github.io/ecma262/#sec-module-namespace-exotic-objects" class="type"><Module Namespace Object></a> | <a href="vm.html#class-vmmodule" class="type"><vm.Module></a> Returning a <code>vm.Module</code> is 1635recommended in order to take advantage of error tracking, and to avoid 1636issues with namespaces that contain <code>then</code> function exports.</li> 1637</ul> 1638</li> 1639<li><code>microtaskMode</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> If set to <code>afterEvaluate</code>, microtasks (tasks 1640scheduled through <code>Promise</code>s and <code>async function</code>s) will be run immediately 1641after the script has run. They are included in the <code>timeout</code> and 1642<code>breakOnSigint</code> scopes in that case.</li> 1643</ul> 1644</li> 1645<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type"><any></a> the result of the very last statement executed in the script.</li> 1646</ul> 1647<p>The <code>vm.runInNewContext()</code> first contextifies the given <code>contextObject</code> (or 1648creates a new <code>contextObject</code> if passed as <code>undefined</code>), compiles the <code>code</code>, 1649runs it within the created context, then returns the result. Running code 1650does not have access to the local scope.</p> 1651<p>If <code>options</code> is a string, then it specifies the filename.</p> 1652<p>The following example compiles and executes code that increments a global 1653variable and sets a new one. These globals are contained in the <code>contextObject</code>.</p> 1654<pre><code class="language-js"><span class="hljs-keyword">const</span> vm = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:vm'</span>); 1655 1656<span class="hljs-keyword">const</span> contextObject = { 1657 <span class="hljs-attr">animal</span>: <span class="hljs-string">'cat'</span>, 1658 <span class="hljs-attr">count</span>: <span class="hljs-number">2</span>, 1659}; 1660 1661vm.<span class="hljs-title function_">runInNewContext</span>(<span class="hljs-string">'count += 1; name = "kitty"'</span>, contextObject); 1662<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(contextObject); 1663<span class="hljs-comment">// Prints: { animal: 'cat', count: 3, name: 'kitty' }</span></code> <button class="copy-button">copy</button></pre> 1664</section><section><h3><code>vm.runInThisContext(code[, options])</code><span><a class="mark" href="#vmruninthiscontextcode-options" id="vmruninthiscontextcode-options">#</a></span><a aria-hidden="true" class="legacy" id="vm_vm_runinthiscontext_code_options"></a></h3> 1665<div class="api_metadata"> 1666<details class="changelog"><summary>History</summary> 1667<table> 1668<tbody><tr><th>Version</th><th>Changes</th></tr> 1669<tr><td>v17.0.0, v16.12.0</td> 1670<td><p>Added support for import attributes to the <code>importModuleDynamically</code> parameter.</p></td></tr> 1671<tr><td>v6.3.0</td> 1672<td><p>The <code>breakOnSigint</code> option is supported now.</p></td></tr> 1673<tr><td>v0.3.1</td> 1674<td><p><span>Added in: v0.3.1</span></p></td></tr> 1675</tbody></table> 1676</details> 1677</div> 1678<ul> 1679<li><code>code</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> The JavaScript code to compile and run.</li> 1680<li><code>options</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> 1681<ul> 1682<li><code>filename</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> Specifies the filename used in stack traces produced 1683by this script. <strong>Default:</strong> <code>'evalmachine.<anonymous>'</code>.</li> 1684<li><code>lineOffset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><number></a> Specifies the line number offset that is displayed 1685in stack traces produced by this script. <strong>Default:</strong> <code>0</code>.</li> 1686<li><code>columnOffset</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><number></a> Specifies the first-line column number offset that 1687is displayed in stack traces produced by this script. <strong>Default:</strong> <code>0</code>.</li> 1688<li><code>displayErrors</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type"><boolean></a> When <code>true</code>, if an <a href="errors.html#class-error"><code>Error</code></a> occurs 1689while compiling the <code>code</code>, the line of code causing the error is attached 1690to the stack trace. <strong>Default:</strong> <code>true</code>.</li> 1691<li><code>timeout</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> Specifies the number of milliseconds to execute <code>code</code> 1692before terminating execution. If execution is terminated, an <a href="errors.html#class-error"><code>Error</code></a> 1693will be thrown. This value must be a strictly positive integer.</li> 1694<li><code>breakOnSigint</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type"><boolean></a> If <code>true</code>, receiving <code>SIGINT</code> 1695(<kbd>Ctrl</kbd>+<kbd>C</kbd>) will terminate execution and throw an 1696<a href="errors.html#class-error"><code>Error</code></a>. Existing handlers for the event that have been attached via 1697<code>process.on('SIGINT')</code> are disabled during script execution, but continue to 1698work after that. <strong>Default:</strong> <code>false</code>.</li> 1699<li><code>cachedData</code> <a href="buffer.html#class-buffer" class="type"><Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray" class="type"><TypedArray></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView" class="type"><DataView></a> Provides an optional <code>Buffer</code> or 1700<code>TypedArray</code>, or <code>DataView</code> with V8's code cache data for the supplied 1701source.</li> 1702<li><code>importModuleDynamically</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function" class="type"><Function></a> Called during evaluation of this module 1703when <code>import()</code> is called. If this option is not specified, calls to 1704<code>import()</code> will reject with <a href="errors.html#err_vm_dynamic_import_callback_missing"><code>ERR_VM_DYNAMIC_IMPORT_CALLBACK_MISSING</code></a>. 1705This option is part of the experimental modules API. We do not recommend 1706using it in a production environment. If <code>--experimental-vm-modules</code> isn't 1707set, this callback will be ignored and calls to <code>import()</code> will reject with 1708<a href="errors.html#err_vm_dynamic_import_callback_missing_flag"><code>ERR_VM_DYNAMIC_IMPORT_CALLBACK_MISSING_FLAG</code></a>. 1709<ul> 1710<li><code>specifier</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> specifier passed to <code>import()</code></li> 1711<li><code>script</code> <a href="vm.html#class-vmscript" class="type"><vm.Script></a></li> 1712<li><code>importAttributes</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a> The <code>"with"</code> value passed to the 1713<a href="https://tc39.es/proposal-import-attributes/#sec-evaluate-import-call"><code>optionsExpression</code></a> optional parameter, or an empty object if no value 1714was provided.</li> 1715<li>Returns: <a href="https://tc39.github.io/ecma262/#sec-module-namespace-exotic-objects" class="type"><Module Namespace Object></a> | <a href="vm.html#class-vmmodule" class="type"><vm.Module></a> Returning a <code>vm.Module</code> is 1716recommended in order to take advantage of error tracking, and to avoid 1717issues with namespaces that contain <code>then</code> function exports.</li> 1718</ul> 1719</li> 1720</ul> 1721</li> 1722<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type"><any></a> the result of the very last statement executed in the script.</li> 1723</ul> 1724<p><code>vm.runInThisContext()</code> compiles <code>code</code>, runs it within the context of the 1725current <code>global</code> and returns the result. Running code does not have access to 1726local scope, but does have access to the current <code>global</code> object.</p> 1727<p>If <code>options</code> is a string, then it specifies the filename.</p> 1728<p>The following example illustrates using both <code>vm.runInThisContext()</code> and 1729the JavaScript <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/eval"><code>eval()</code></a> function to run the same code:</p> 1730<!-- eslint-disable prefer-const --> 1731<pre><code class="language-js"><span class="hljs-keyword">const</span> vm = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:vm'</span>); 1732<span class="hljs-keyword">let</span> localVar = <span class="hljs-string">'initial value'</span>; 1733 1734<span class="hljs-keyword">const</span> vmResult = vm.<span class="hljs-title function_">runInThisContext</span>(<span class="hljs-string">'localVar = "vm";'</span>); 1735<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-string">`vmResult: '<span class="hljs-subst">${vmResult}</span>', localVar: '<span class="hljs-subst">${localVar}</span>'`</span>); 1736<span class="hljs-comment">// Prints: vmResult: 'vm', localVar: 'initial value'</span> 1737 1738<span class="hljs-keyword">const</span> evalResult = <span class="hljs-built_in">eval</span>(<span class="hljs-string">'localVar = "eval";'</span>); 1739<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-string">`evalResult: '<span class="hljs-subst">${evalResult}</span>', localVar: '<span class="hljs-subst">${localVar}</span>'`</span>); 1740<span class="hljs-comment">// Prints: evalResult: 'eval', localVar: 'eval'</span></code> <button class="copy-button">copy</button></pre> 1741<p>Because <code>vm.runInThisContext()</code> does not have access to the local scope, 1742<code>localVar</code> is unchanged. In contrast, <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/eval"><code>eval()</code></a> <em>does</em> have access to the 1743local scope, so the value <code>localVar</code> is changed. In this way 1744<code>vm.runInThisContext()</code> is much like an <a href="https://es5.github.io/#x10.4.2">indirect <code>eval()</code> call</a>, e.g. 1745<code>(0,eval)('code')</code>.</p> 1746</section><section><h3>Example: Running an HTTP server within a VM<span><a class="mark" href="#example-running-an-http-server-within-a-vm" id="example-running-an-http-server-within-a-vm">#</a></span><a aria-hidden="true" class="legacy" id="vm_example_running_an_http_server_within_a_vm"></a></h3> 1747<p>When using either <a href="#scriptruninthiscontextoptions"><code>script.runInThisContext()</code></a> or 1748<a href="#vmruninthiscontextcode-options"><code>vm.runInThisContext()</code></a>, the code is executed within the current V8 global 1749context. The code passed to this VM context will have its own isolated scope.</p> 1750<p>In order to run a simple web server using the <code>node:http</code> module the code passed 1751to the context must either call <code>require('node:http')</code> on its own, or have a 1752reference to the <code>node:http</code> module passed to it. For instance:</p> 1753<pre><code class="language-js"><span class="hljs-meta">'use strict'</span>; 1754<span class="hljs-keyword">const</span> vm = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:vm'</span>); 1755 1756<span class="hljs-keyword">const</span> code = <span class="hljs-string">` 1757((require) => { 1758 const http = require('node:http'); 1759 1760 http.createServer((request, response) => { 1761 response.writeHead(200, { 'Content-Type': 'text/plain' }); 1762 response.end('Hello World\\n'); 1763 }).listen(8124); 1764 1765 console.log('Server running at http://127.0.0.1:8124/'); 1766})`</span>; 1767 1768vm.<span class="hljs-title function_">runInThisContext</span>(code)(<span class="hljs-built_in">require</span>);</code> <button class="copy-button">copy</button></pre> 1769<p>The <code>require()</code> in the above case shares the state with the context it is 1770passed from. This may introduce risks when untrusted code is executed, e.g. 1771altering objects in the context in unwanted ways.</p> 1772</section><section><h3>What does it mean to "contextify" an object?<span><a class="mark" href="#what-does-it-mean-to-contextify-an-object" id="what-does-it-mean-to-contextify-an-object">#</a></span><a aria-hidden="true" class="legacy" id="vm_what_does_it_mean_to_contextify_an_object"></a></h3> 1773<p>All JavaScript executed within Node.js runs within the scope of a "context". 1774According to the <a href="https://v8.dev/docs/embed#contexts">V8 Embedder's Guide</a>:</p> 1775<blockquote> 1776<p>In V8, a context is an execution environment that allows separate, unrelated, 1777JavaScript applications to run in a single instance of V8. You must explicitly 1778specify the context in which you want any JavaScript code to be run.</p> 1779</blockquote> 1780<p>When the method <code>vm.createContext()</code> is called, the <code>contextObject</code> argument 1781(or a newly-created object if <code>contextObject</code> is <code>undefined</code>) is associated 1782internally with a new instance of a V8 Context. This V8 Context provides the 1783<code>code</code> run using the <code>node:vm</code> module's methods with an isolated global 1784environment within which it can operate. The process of creating the V8 Context 1785and associating it with the <code>contextObject</code> is what this document refers to as 1786"contextifying" the object.</p> 1787</section><section><h3>Timeout interactions with asynchronous tasks and Promises<span><a class="mark" href="#timeout-interactions-with-asynchronous-tasks-and-promises" id="timeout-interactions-with-asynchronous-tasks-and-promises">#</a></span><a aria-hidden="true" class="legacy" id="vm_timeout_interactions_with_asynchronous_tasks_and_promises"></a></h3> 1788<p><code>Promise</code>s and <code>async function</code>s can schedule tasks run by the JavaScript 1789engine asynchronously. By default, these tasks are run after all JavaScript 1790functions on the current stack are done executing. 1791This allows escaping the functionality of the <code>timeout</code> and 1792<code>breakOnSigint</code> options.</p> 1793<p>For example, the following code executed by <code>vm.runInNewContext()</code> with a 1794timeout of 5 milliseconds schedules an infinite loop to run after a promise 1795resolves. The scheduled loop is never interrupted by the timeout:</p> 1796<pre><code class="language-js"><span class="hljs-keyword">const</span> vm = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:vm'</span>); 1797 1798<span class="hljs-keyword">function</span> <span class="hljs-title function_">loop</span>(<span class="hljs-params"></span>) { 1799 <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-string">'entering loop'</span>); 1800 <span class="hljs-keyword">while</span> (<span class="hljs-number">1</span>) <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-title class_">Date</span>.<span class="hljs-title function_">now</span>()); 1801} 1802 1803vm.<span class="hljs-title function_">runInNewContext</span>( 1804 <span class="hljs-string">'Promise.resolve().then(() => loop());'</span>, 1805 { loop, <span class="hljs-variable language_">console</span> }, 1806 { <span class="hljs-attr">timeout</span>: <span class="hljs-number">5</span> }, 1807); 1808<span class="hljs-comment">// This is printed *before* 'entering loop' (!)</span> 1809<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-string">'done executing'</span>);</code> <button class="copy-button">copy</button></pre> 1810<p>This can be addressed by passing <code>microtaskMode: 'afterEvaluate'</code> to the code 1811that creates the <code>Context</code>:</p> 1812<pre><code class="language-js"><span class="hljs-keyword">const</span> vm = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:vm'</span>); 1813 1814<span class="hljs-keyword">function</span> <span class="hljs-title function_">loop</span>(<span class="hljs-params"></span>) { 1815 <span class="hljs-keyword">while</span> (<span class="hljs-number">1</span>) <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-title class_">Date</span>.<span class="hljs-title function_">now</span>()); 1816} 1817 1818vm.<span class="hljs-title function_">runInNewContext</span>( 1819 <span class="hljs-string">'Promise.resolve().then(() => loop());'</span>, 1820 { loop, <span class="hljs-variable language_">console</span> }, 1821 { <span class="hljs-attr">timeout</span>: <span class="hljs-number">5</span>, <span class="hljs-attr">microtaskMode</span>: <span class="hljs-string">'afterEvaluate'</span> }, 1822);</code> <button class="copy-button">copy</button></pre> 1823<p>In this case, the microtask scheduled through <code>promise.then()</code> will be run 1824before returning from <code>vm.runInNewContext()</code>, and will be interrupted 1825by the <code>timeout</code> functionality. This applies only to code running in a 1826<code>vm.Context</code>, so e.g. <a href="#vmruninthiscontextcode-options"><code>vm.runInThisContext()</code></a> does not take this option.</p> 1827<p>Promise callbacks are entered into the microtask queue of the context in which 1828they were created. For example, if <code>() => loop()</code> is replaced with just <code>loop</code> 1829in the above example, then <code>loop</code> will be pushed into the global microtask 1830queue, because it is a function from the outer (main) context, and thus will 1831also be able to escape the timeout.</p> 1832<p>If asynchronous scheduling functions such as <code>process.nextTick()</code>, 1833<code>queueMicrotask()</code>, <code>setTimeout()</code>, <code>setImmediate()</code>, etc. are made available 1834inside a <code>vm.Context</code>, functions passed to them will be added to global queues, 1835which are shared by all contexts. Therefore, callbacks passed to those functions 1836are not controllable through the timeout either.</p></section> 1837 <!-- API END --> 1838 </div> 1839 </div> 1840 </div> 1841</body> 1842</html> 1843