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<!doctype html>
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<title>VM (Executing JavaScript) | Node.js v12.0.0 Documentation</title>
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</header>
<div id="toc">
<h2>Table of Contents</h2>
<ul>
<li>
<p><span class="stability_2"><a href="#vm_vm_executing_javascript">VM (Executing JavaScript)</a></span></p>
<ul>
<li>
<p><span class="stability_1"><a href="#vm_class_vm_sourcetextmodule">Class: vm.SourceTextModule</a></span></p>
<ul>
<li><a href="#vm_constructor_new_vm_sourcetextmodule_code_options">Constructor: new vm.SourceTextModule(code[, options])</a></li>
<li><a href="#vm_module_dependencyspecifiers">module.dependencySpecifiers</a></li>
<li><a href="#vm_module_error">module.error</a></li>
<li><a href="#vm_module_evaluate_options">module.evaluate([options])</a></li>
<li><a href="#vm_module_instantiate">module.instantiate()</a></li>
<li><a href="#vm_module_link_linker">module.link(linker)</a></li>
<li><a href="#vm_module_linkingstatus">module.linkingStatus</a></li>
<li><a href="#vm_module_namespace">module.namespace</a></li>
<li><a href="#vm_module_status">module.status</a></li>
<li><a href="#vm_module_url">module.url</a></li>
</ul>
</li>
<li>
<p><a href="#vm_class_vm_script">Class: vm.Script</a></p>
<ul>
<li><a href="#vm_new_vm_script_code_options">new vm.Script(code, options)</a></li>
<li><a href="#vm_script_createcacheddata">script.createCachedData()</a></li>
<li><a href="#vm_script_runincontext_contextifiedsandbox_options">script.runInContext(contextifiedSandbox[, options])</a></li>
<li><a href="#vm_script_runinnewcontext_sandbox_options">script.runInNewContext([sandbox[, options]])</a></li>
<li><a href="#vm_script_runinthiscontext_options">script.runInThisContext([options])</a></li>
</ul>
</li>
<li><a href="#vm_vm_compilefunction_code_params_options">vm.compileFunction(code[, params[, options]])</a></li>
<li><a href="#vm_vm_createcontext_sandbox_options">vm.createContext([sandbox[, options]])</a></li>
<li><a href="#vm_vm_iscontext_sandbox">vm.isContext(sandbox)</a></li>
<li><a href="#vm_vm_runincontext_code_contextifiedsandbox_options">vm.runInContext(code, contextifiedSandbox[, options])</a></li>
<li><a href="#vm_vm_runinnewcontext_code_sandbox_options">vm.runInNewContext(code[, sandbox[, options]])</a></li>
<li><a href="#vm_vm_runinthiscontext_code_options">vm.runInThisContext(code[, options])</a></li>
<li><a href="#vm_example_running_an_http_server_within_a_vm">Example: Running an HTTP Server within a VM</a></li>
<li><a href="#vm_what_does_it_mean_to_contextify_an_object">What does it mean to "contextify" an object?</a></li>
<li><a href="#vm_timeout_limitations_when_using_process_nexttick_promises_and_queuemicrotask">Timeout limitations when using process.nextTick(), Promises, and queueMicrotask()</a></li>
</ul>
</li>
</ul>
</div>
<div id="apicontent">
<h1>VM (Executing JavaScript)<span><a class="mark" href="#vm_vm_executing_javascript" id="vm_vm_executing_javascript">#</a></span></h1>
<p></p><div class="api_stability api_stability_2"><a href="documentation.html#documentation_stability_index">Stability: 2</a> - Stable</div><p></p>
<p>The <code>vm</code> module provides APIs for compiling and running code within V8 Virtual
Machine contexts. <strong>The <code>vm</code> module is not a security mechanism. Do
not use it to run untrusted code</strong>. The term "sandbox" is used throughout these
docs simply to refer to a separate context, and does not confer any security
guarantees.</p>
<p>JavaScript code can be compiled and run immediately or
compiled, saved, and run later.</p>
<p>A common use case is to run the code in a sandboxed environment.
The sandboxed code uses a different V8 Context, meaning that
it has a different global object than the rest of the code.</p>
<p>One can provide the context by <a href="#vm_what_does_it_mean_to_contextify_an_object">"contextifying"</a> a sandbox
object. The sandboxed code treats any property in the sandbox like a
global variable. Any changes to global variables caused by the sandboxed
code are reflected in the sandbox object.</p>
<pre><code class="language-js"><span class="hljs-keyword">const</span> vm = <span class="hljs-built_in">require</span>(<span class="hljs-string">'vm'</span>);
<span class="hljs-keyword">const</span> x = <span class="hljs-number">1</span>;
<span class="hljs-keyword">const</span> sandbox = { <span class="hljs-attr">x</span>: <span class="hljs-number">2</span> };
vm.createContext(sandbox); <span class="hljs-comment">// Contextify the sandbox.</span>
<span class="hljs-keyword">const</span> code = <span class="hljs-string">'x += 40; var y = 17;'</span>;
<span class="hljs-comment">// x and y are global variables in the sandboxed environment.</span>
<span class="hljs-comment">// Initially, x has the value 2 because that is the value of sandbox.x.</span>
vm.runInContext(code, sandbox);
<span class="hljs-built_in">console</span>.log(sandbox.x); <span class="hljs-comment">// 42</span>
<span class="hljs-built_in">console</span>.log(sandbox.y); <span class="hljs-comment">// 17</span>
<span class="hljs-built_in">console</span>.log(x); <span class="hljs-comment">// 1; y is not defined.</span></code></pre>
<h2>Class: vm.SourceTextModule<span><a class="mark" href="#vm_class_vm_sourcetextmodule" id="vm_class_vm_sourcetextmodule">#</a></span></h2>
<div class="api_metadata">
<span>Added in: v9.6.0</span>
</div>
<p></p><div class="api_stability api_stability_1"><a href="documentation.html#documentation_stability_index">Stability: 1</a> - Experimental</div><p></p>
<p><em>This feature is only available with the <code>--experimental-vm-modules</code> command
flag enabled.</em></p>
<p>The <code>vm.SourceTextModule</code> class provides a low-level interface for using
ECMAScript modules in VM contexts. It is the counterpart of the <code>vm.Script</code>
class that closely mirrors <a href="https://tc39.github.io/ecma262/#sec-source-text-module-records">Source Text Module Record</a>s as defined in the
ECMAScript specification.</p>
<p>Unlike <code>vm.Script</code> however, every <code>vm.SourceTextModule</code> object is bound to a
context from its creation. Operations on <code>vm.SourceTextModule</code> objects are
intrinsically asynchronous, in contrast with the synchronous nature of
<code>vm.Script</code> objects. With the help of async functions, however, manipulating
<code>vm.SourceTextModule</code> objects is fairly straightforward.</p>
<p>Using a <code>vm.SourceTextModule</code> object requires four distinct steps:
creation/parsing, linking, instantiation, and evaluation. These four steps are
illustrated in the following example.</p>
<p>This implementation lies at a lower level than the <a href="esm.html#esm_ecmascript_modules">ECMAScript Module
loader</a>. There is also currently no way to interact with the Loader, though
support is planned.</p>
<pre><code class="language-js"><span class="hljs-keyword">const</span> vm = <span class="hljs-built_in">require</span>(<span class="hljs-string">'vm'</span>);
<span class="hljs-keyword">const</span> contextifiedSandbox = vm.createContext({ <span class="hljs-attr">secret</span>: <span class="hljs-number">42</span> });
<span class="hljs-function">(<span class="hljs-params"><span class="hljs-keyword">async</span> (</span>) =></span> {
<span class="hljs-comment">// Step 1</span>
<span class="hljs-comment">//</span>
<span class="hljs-comment">// Create a Module by constructing a new `vm.SourceTextModule` object. This</span>
<span class="hljs-comment">// parses the provided source text, throwing a `SyntaxError` if anything goes</span>
<span class="hljs-comment">// wrong. By default, a Module is created in the top context. But here, we</span>
<span class="hljs-comment">// specify `contextifiedSandbox` as the context this Module belongs to.</span>
<span class="hljs-comment">//</span>
<span class="hljs-comment">// Here, we attempt to obtain the default export from the module "foo", and</span>
<span class="hljs-comment">// put it into local binding "secret".</span>
<span class="hljs-keyword">const</span> bar = <span class="hljs-keyword">new</span> vm.SourceTextModule(<span class="hljs-string">`
import s from 'foo';
s;
`</span>, { <span class="hljs-attr">context</span>: contextifiedSandbox });
<span class="hljs-comment">// Step 2</span>
<span class="hljs-comment">//</span>
<span class="hljs-comment">// "Link" the imported dependencies of this Module to it.</span>
<span class="hljs-comment">//</span>
<span class="hljs-comment">// The provided linking callback (the "linker") accepts two arguments: the</span>
<span class="hljs-comment">// parent module (`bar` in this case) and the string that is the specifier of</span>
<span class="hljs-comment">// the imported module. The callback is expected to return a Module that</span>
<span class="hljs-comment">// corresponds to the provided specifier, with certain requirements documented</span>
<span class="hljs-comment">// in `module.link()`.</span>
<span class="hljs-comment">//</span>
<span class="hljs-comment">// If linking has not started for the returned Module, the same linker</span>
<span class="hljs-comment">// callback will be called on the returned Module.</span>
<span class="hljs-comment">//</span>
<span class="hljs-comment">// Even top-level Modules without dependencies must be explicitly linked. The</span>
<span class="hljs-comment">// callback provided would never be called, however.</span>
<span class="hljs-comment">//</span>
<span class="hljs-comment">// The link() method returns a Promise that will be resolved when all the</span>
<span class="hljs-comment">// Promises returned by the linker resolve.</span>
<span class="hljs-comment">//</span>
<span class="hljs-comment">// Note: This is a contrived example in that the linker function creates a new</span>
<span class="hljs-comment">// "foo" module every time it is called. In a full-fledged module system, a</span>
<span class="hljs-comment">// cache would probably be used to avoid duplicated modules.</span>
<span class="hljs-keyword">async</span> <span class="hljs-function"><span class="hljs-keyword">function</span> <span class="hljs-title">linker</span>(<span class="hljs-params">specifier, referencingModule</span>) </span>{
<span class="hljs-keyword">if</span> (specifier === <span class="hljs-string">'foo'</span>) {
<span class="hljs-keyword">return</span> <span class="hljs-keyword">new</span> vm.SourceTextModule(<span class="hljs-string">`
// The "secret" variable refers to the global variable we added to
// "contextifiedSandbox" when creating the context.
export default secret;
`</span>, { <span class="hljs-attr">context</span>: referencingModule.context });
<span class="hljs-comment">// Using `contextifiedSandbox` instead of `referencingModule.context`</span>
<span class="hljs-comment">// here would work as well.</span>
}
<span class="hljs-keyword">throw</span> <span class="hljs-keyword">new</span> <span class="hljs-built_in">Error</span>(<span class="hljs-string">`Unable to resolve dependency: <span class="hljs-subst">${specifier}</span>`</span>);
}
<span class="hljs-keyword">await</span> bar.link(linker);
<span class="hljs-comment">// Step 3</span>
<span class="hljs-comment">//</span>
<span class="hljs-comment">// Instantiate the top-level Module.</span>
<span class="hljs-comment">//</span>
<span class="hljs-comment">// Only the top-level Module needs to be explicitly instantiated; its</span>
<span class="hljs-comment">// dependencies will be recursively instantiated by instantiate().</span>
bar.instantiate();
<span class="hljs-comment">// Step 4</span>
<span class="hljs-comment">//</span>
<span class="hljs-comment">// Evaluate the Module. The evaluate() method returns a Promise with a single</span>
<span class="hljs-comment">// property "result" that contains the result of the very last statement</span>
<span class="hljs-comment">// executed in the Module. In the case of `bar`, it is `s;`, which refers to</span>
<span class="hljs-comment">// the default export of the `foo` module, the `secret` we set in the</span>
<span class="hljs-comment">// beginning to 42.</span>
<span class="hljs-keyword">const</span> { result } = <span class="hljs-keyword">await</span> bar.evaluate();
<span class="hljs-built_in">console</span>.log(result);
<span class="hljs-comment">// Prints 42.</span>
})();</code></pre>
<h3>Constructor: new vm.SourceTextModule(code[, options])<span><a class="mark" href="#vm_constructor_new_vm_sourcetextmodule_code_options" id="vm_constructor_new_vm_sourcetextmodule_code_options">#</a></span></h3>
<ul>
<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>
<li>
<p><code>options</code></p>
<ul>
<li><code>url</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> URL used in module resolution and stack traces. <strong>Default:</strong>
<code>'vm:module(i)'</code> where <code>i</code> is a context-specific ascending index.</li>
<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="#vm_what_does_it_mean_to_contextify_an_object">contextified</a> object as returned by the
<code>vm.createContext()</code> method, to compile and evaluate this <code>Module</code> in.</li>
<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
in stack traces produced by this <code>Module</code>.</li>
<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 column number offset that is
displayed in stack traces produced by this <code>Module</code>.</li>
<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>
to initialize the <code>import.meta</code>. This function has the signature <code>(meta, module)</code>, where <code>meta</code> is the <code>import.meta</code> object in the <code>Module</code>, and
<code>module</code> is this <code>vm.SourceTextModule</code> object.</li>
<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 when <code>import()</code> is called. This function has the signature
<code>(specifier, module)</code> where <code>specifier</code> is the specifier passed to
<code>import()</code> and <code>module</code> is this <code>vm.SourceTextModule</code>. If this option is
not specified, calls to <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>. This method can return a
<a href="https://tc39.github.io/ecma262/#sec-module-namespace-exotic-objects">Module Namespace Object</a>, but returning a <code>vm.SourceTextModule</code> is
recommended in order to take advantage of error tracking, and to avoid
issues with namespaces that contain <code>then</code> function exports.</li>
</ul>
</li>
</ul>
<p>Creates a new ES <code>Module</code> object.</p>
<p>Properties assigned to the <code>import.meta</code> object that are objects may
allow the <code>Module</code> to access information outside the specified <code>context</code>, if the
object is created in the top level context. Use <code>vm.runInContext()</code> to create
objects in a specific context.</p>
<pre><code class="language-js"><span class="hljs-keyword">const</span> vm = <span class="hljs-built_in">require</span>(<span class="hljs-string">'vm'</span>);
<span class="hljs-keyword">const</span> contextifiedSandbox = vm.createContext({ <span class="hljs-attr">secret</span>: <span class="hljs-number">42</span> });
<span class="hljs-function">(<span class="hljs-params"><span class="hljs-keyword">async</span> (</span>) =></span> {
<span class="hljs-keyword">const</span> <span class="hljs-built_in">module</span> = <span class="hljs-keyword">new</span> vm.SourceTextModule(
<span class="hljs-string">'Object.getPrototypeOf(import.meta.prop).secret = secret;'</span>,
{
initializeImportMeta(meta) {
<span class="hljs-comment">// Note: this object is created in the top context. As such,</span>
<span class="hljs-comment">// Object.getPrototypeOf(import.meta.prop) points to the</span>
<span class="hljs-comment">// Object.prototype in the top context rather than that in</span>
<span class="hljs-comment">// the sandbox.</span>
meta.prop = {};
}
});
<span class="hljs-comment">// Since module has no dependencies, the linker function will never be called.</span>
<span class="hljs-keyword">await</span> <span class="hljs-built_in">module</span>.link(<span class="hljs-function"><span class="hljs-params">()</span> =></span> {});
<span class="hljs-built_in">module</span>.instantiate();
<span class="hljs-keyword">await</span> <span class="hljs-built_in">module</span>.evaluate();
<span class="hljs-comment">// Now, Object.prototype.secret will be equal to 42.</span>
<span class="hljs-comment">//</span>
<span class="hljs-comment">// To fix this problem, replace</span>
<span class="hljs-comment">// meta.prop = {};</span>
<span class="hljs-comment">// above with</span>
<span class="hljs-comment">// meta.prop = vm.runInContext('{}', contextifiedSandbox);</span>
})();</code></pre>
<h3>module.dependencySpecifiers<span><a class="mark" href="#vm_module_dependencyspecifiers" id="vm_module_dependencyspecifiers">#</a></span></h3>
<ul>
<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string[]></a></li>
</ul>
<p>The specifiers of all dependencies of this module. The returned array is frozen
to disallow any changes to it.</p>
<p>Corresponds to the <code>[[RequestedModules]]</code> field of
<a href="https://tc39.github.io/ecma262/#sec-source-text-module-records">Source Text Module Record</a>s in the ECMAScript specification.</p>
<h3>module.error<span><a class="mark" href="#vm_module_error" id="vm_module_error">#</a></span></h3>
<ul>
<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type"><any></a></li>
</ul>
<p>If the <code>module.status</code> is <code>'errored'</code>, this property contains the exception
thrown by the module during evaluation. If the status is anything else,
accessing this property will result in a thrown exception.</p>
<p>The value <code>undefined</code> cannot be used for cases where there is not a thrown
exception due to possible ambiguity with <code>throw undefined;</code>.</p>
<p>Corresponds to the <code>[[EvaluationError]]</code> field of <a href="https://tc39.github.io/ecma262/#sec-source-text-module-records">Source Text Module Record</a>s
in the ECMAScript specification.</p>
<h3>module.evaluate([options])<span><a class="mark" href="#vm_module_evaluate_options" id="vm_module_evaluate_options">#</a></span></h3>
<ul>
<li>
<p><code>options</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a></p>
<ul>
<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
before terminating execution. If execution is interrupted, an <a href="errors.html#errors_class_error"><code>Error</code></a>
will be thrown. This value must be a strictly positive integer.</li>
<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>, the execution will be terminated when
<code>SIGINT</code> (Ctrl+C) is received. Existing handlers for the event that have
been attached via <code>process.on('SIGINT')</code> will be disabled during script
execution, but will continue to work after that. If execution is
interrupted, an <a href="errors.html#errors_class_error"><code>Error</code></a> will be thrown.</li>
</ul>
</li>
<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise" class="type"><Promise></a></li>
</ul>
<p>Evaluate the module.</p>
<p>This must be called after the module has been instantiated; otherwise it will
throw an error. It could be called also when the module has already been
evaluated, in which case it will do one of the following two things:</p>
<ul>
<li>return <code>undefined</code> if the initial evaluation ended in success (<code>module.status</code>
is <code>'evaluated'</code>)</li>
<li>rethrow the same exception the initial evaluation threw if the initial
evaluation ended in an error (<code>module.status</code> is <code>'errored'</code>)</li>
</ul>
<p>This method cannot be called while the module is being evaluated
(<code>module.status</code> is <code>'evaluating'</code>) to prevent infinite recursion.</p>
<p>Corresponds to the <a href="https://tc39.github.io/ecma262/#sec-moduleevaluation">Evaluate() concrete method</a> field of <a href="https://tc39.github.io/ecma262/#sec-source-text-module-records">Source Text Module
Record</a>s in the ECMAScript specification.</p>
<h3>module.instantiate()<span><a class="mark" href="#vm_module_instantiate" id="vm_module_instantiate">#</a></span></h3>
<p>Instantiate the module. This must be called after linking has completed
(<code>linkingStatus</code> is <code>'linked'</code>); otherwise it will throw an error. It may also
throw an exception if one of the dependencies does not provide an export the
parent module requires.</p>
<p>However, if this function succeeded, further calls to this function after the
initial instantiation will be no-ops, to be consistent with the ECMAScript
specification.</p>
<p>Unlike other methods operating on <code>Module</code>, this function completes
synchronously and returns nothing.</p>
<p>Corresponds to the <a href="https://tc39.github.io/ecma262/#sec-moduledeclarationinstantiation">Instantiate() concrete method</a> field of <a href="https://tc39.github.io/ecma262/#sec-source-text-module-records">Source Text
Module Record</a>s in the ECMAScript specification.</p>
<h3>module.link(linker)<span><a class="mark" href="#vm_module_link_linker" id="vm_module_link_linker">#</a></span></h3>
<ul>
<li><code>linker</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function" class="type"><Function></a></li>
<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise" class="type"><Promise></a></li>
</ul>
<p>Link module dependencies. This method must be called before instantiation, and
can only be called once per module.</p>
<p>Two parameters will be passed to the <code>linker</code> function:</p>
<ul>
<li>
<p><code>specifier</code> The specifier of the requested module:</p>
<!-- eslint-skip -->
<pre><code class="language-js"><span class="hljs-keyword">import</span> foo <span class="hljs-keyword">from</span> <span class="hljs-string">'foo'</span>;
<span class="hljs-comment">// ^^^^^ the module specifier</span></code></pre>
</li>
<li><code>referencingModule</code> The <code>Module</code> object <code>link()</code> is called on.</li>
</ul>
<p>The function is expected to return a <code>Module</code> object or a <code>Promise</code> that
eventually resolves to a <code>Module</code> object. The returned <code>Module</code> must satisfy the
following two invariants:</p>
<ul>
<li>It must belong to the same context as the parent <code>Module</code>.</li>
<li>Its <code>linkingStatus</code> must not be <code>'errored'</code>.</li>
</ul>
<p>If the returned <code>Module</code>'s <code>linkingStatus</code> is <code>'unlinked'</code>, this method will be
recursively called on the returned <code>Module</code> with the same provided <code>linker</code>
function.</p>
<p><code>link()</code> returns a <code>Promise</code> that will either get resolved when all linking
instances resolve to a valid <code>Module</code>, or rejected if the linker function either
throws an exception or returns an invalid <code>Module</code>.</p>
<p>The linker function roughly corresponds to the implementation-defined
<a href="https://tc39.github.io/ecma262/#sec-hostresolveimportedmodule">HostResolveImportedModule</a> abstract operation in the ECMAScript
specification, with a few key differences:</p>
<ul>
<li>The linker function is allowed to be asynchronous while
<a href="https://tc39.github.io/ecma262/#sec-hostresolveimportedmodule">HostResolveImportedModule</a> is synchronous.</li>
<li>The linker function is executed during linking, a Node.js-specific stage
before instantiation, while <a href="https://tc39.github.io/ecma262/#sec-hostresolveimportedmodule">HostResolveImportedModule</a> is called during
instantiation.</li>
</ul>
<p>The actual <a href="https://tc39.github.io/ecma262/#sec-hostresolveimportedmodule">HostResolveImportedModule</a> implementation used during module
instantiation is one that returns the modules linked during linking. Since at
that point all modules would have been fully linked already, the
<a href="https://tc39.github.io/ecma262/#sec-hostresolveimportedmodule">HostResolveImportedModule</a> implementation is fully synchronous per
specification.</p>
<h3>module.linkingStatus<span><a class="mark" href="#vm_module_linkingstatus" id="vm_module_linkingstatus">#</a></span></h3>
<ul>
<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a></li>
</ul>
<p>The current linking status of <code>module</code>. It will be one of the following values:</p>
<ul>
<li><code>'unlinked'</code>: <code>module.link()</code> has not yet been called.</li>
<li><code>'linking'</code>: <code>module.link()</code> has been called, but not all Promises returned by
the linker function have been resolved yet.</li>
<li><code>'linked'</code>: <code>module.link()</code> has been called, and all its dependencies have
been successfully linked.</li>
<li><code>'errored'</code>: <code>module.link()</code> has been called, but at least one of its
dependencies failed to link, either because the callback returned a <code>Promise</code>
that is rejected, or because the <code>Module</code> the callback returned is invalid.</li>
</ul>
<h3>module.namespace<span><a class="mark" href="#vm_module_namespace" id="vm_module_namespace">#</a></span></h3>
<ul>
<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a></li>
</ul>
<p>The namespace object of the module. This is only available after instantiation
(<code>module.instantiate()</code>) has completed.</p>
<p>Corresponds to the <a href="https://tc39.github.io/ecma262/#sec-getmodulenamespace">GetModuleNamespace</a> abstract operation in the ECMAScript
specification.</p>
<h3>module.status<span><a class="mark" href="#vm_module_status" id="vm_module_status">#</a></span></h3>
<ul>
<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a></li>
</ul>
<p>The current status of the module. Will be one of:</p>
<ul>
<li>
<p><code>'uninstantiated'</code>: The module is not instantiated. It may because of any of
the following reasons:</p>
<ul>
<li>The module was just created.</li>
<li><code>module.instantiate()</code> has been called on this module, but it failed for
some reason.</li>
</ul>
<p>This status does not convey any information regarding if <code>module.link()</code> has
been called. See <code>module.linkingStatus</code> for that.</p>
</li>
<li>
<p><code>'instantiating'</code>: The module is currently being instantiated through a
<code>module.instantiate()</code> call on itself or a parent module.</p>
</li>
<li>
<p><code>'instantiated'</code>: The module has been instantiated successfully, but
<code>module.evaluate()</code> has not yet been called.</p>
</li>
<li>
<p><code>'evaluating'</code>: The module is being evaluated through a <code>module.evaluate()</code> on
itself or a parent module.</p>
</li>
<li>
<p><code>'evaluated'</code>: The module has been successfully evaluated.</p>
</li>
<li>
<p><code>'errored'</code>: The module has been evaluated, but an exception was thrown.</p>
</li>
</ul>
<p>Other than <code>'errored'</code>, this status string corresponds to the specification's
<a href="https://tc39.github.io/ecma262/#sec-source-text-module-records">Source Text Module Record</a>'s <code>[[Status]]</code> field. <code>'errored'</code> corresponds to
<code>'evaluated'</code> in the specification, but with <code>[[EvaluationError]]</code> set to a
value that is not <code>undefined</code>.</p>
<h3>module.url<span><a class="mark" href="#vm_module_url" id="vm_module_url">#</a></span></h3>
<ul>
<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a></li>
</ul>
<p>The URL of the current module, as set in the constructor.</p>
<h2>Class: vm.Script<span><a class="mark" href="#vm_class_vm_script" id="vm_class_vm_script">#</a></span></h2>
<div class="api_metadata">
<span>Added in: v0.3.1</span>
</div>
<p>Instances of the <code>vm.Script</code> class contain precompiled scripts that can be
executed in specific sandboxes (or "contexts").</p>
<h3>new vm.Script(code, options)<span><a class="mark" href="#vm_new_vm_script_code_options" id="vm_new_vm_script_code_options">#</a></span></h3>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v10.6.0</td>
<td><p>The <code>produceCachedData</code> is deprecated in favour of <code>script.createCachedData()</code></p></td></tr>
<tr><td>v5.7.0</td>
<td><p>The <code>cachedData</code> and <code>produceCachedData</code> options are supported now.</p></td></tr>
<tr><td>v0.3.1</td>
<td><p><span>Added in: v0.3.1</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<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>
<li>
<p><code>options</code></p>
<ul>
<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
by this script.</li>
<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
in stack traces produced by this script.</li>
<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 column number offset that is displayed
in stack traces produced by this script.</li>
<li><code>cachedData</code> <a href="buffer.html#buffer_class_buffer" class="type"><Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/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
<code>TypedArray</code>, or <code>DataView</code> with V8's code cache data for the supplied
source. When supplied, the <code>cachedDataRejected</code> value will be set to
either <code>true</code> or <code>false</code> depending on acceptance of the data by V8.</li>
<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
will attempt to produce code cache data for <code>code</code>. Upon success, a
<code>Buffer</code> with V8's code cache data will be produced and stored in the
<code>cachedData</code> property of the returned <code>vm.Script</code> instance.
The <code>cachedDataProduced</code> value will be set to either <code>true</code> or <code>false</code>
depending on whether code cache data is produced successfully.
This option is deprecated in favor of <code>script.createCachedData()</code>.</li>
<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 when <code>import()</code> is called. This function has the signature
<code>(specifier, module)</code> where <code>specifier</code> is the specifier passed to
<code>import()</code> and <code>module</code> is this <code>vm.SourceTextModule</code>. If this option is
not specified, calls to <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>. This method can return a
<a href="https://tc39.github.io/ecma262/#sec-module-namespace-exotic-objects">Module Namespace Object</a>, but returning a <code>vm.SourceTextModule</code> is
recommended in order to take advantage of error tracking, and to avoid
issues with namespaces that contain <code>then</code> function exports.</li>
</ul>
</li>
</ul>
<p>Creating a new <code>vm.Script</code> object compiles <code>code</code> but does not run it. The
compiled <code>vm.Script</code> can be run later multiple times. The <code>code</code> is not bound to
any global object; rather, it is bound before each run, just for that run.</p>
<h3>script.createCachedData()<span><a class="mark" href="#vm_script_createcacheddata" id="vm_script_createcacheddata">#</a></span></h3>
<div class="api_metadata">
<span>Added in: v10.6.0</span>
</div>
<ul>
<li>Returns: <a href="buffer.html#buffer_class_buffer" class="type"><Buffer></a></li>
</ul>
<p>Creates a code cache that can be used with the Script constructor's
<code>cachedData</code> option. Returns a Buffer. This method may be called at any
time and any number of times.</p>
<pre><code class="language-js"><span class="hljs-keyword">const</span> script = <span class="hljs-keyword">new</span> vm.Script(<span class="hljs-string">`
function add(a, b) {
return a + b;
}
const x = add(1, 2);
`</span>);
<span class="hljs-keyword">const</span> cacheWithoutX = script.createCachedData();
script.runInThisContext();
<span class="hljs-keyword">const</span> cacheWithX = script.createCachedData();</code></pre>
<h3>script.runInContext(contextifiedSandbox[, options])<a class="srclink" href="https://github.com/runkitdev/node/blob/cf1ce2bcc1a88ef6ff1bf745a19913a69607fb02/lib/vm.js#L126">[src]</a><span><a class="mark" href="#vm_script_runincontext_contextifiedsandbox_options" id="vm_script_runincontext_contextifiedsandbox_options">#</a></span></h3>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v6.3.0</td>
<td><p>The <code>breakOnSigint</code> option is supported now.</p></td></tr>
<tr><td>v0.3.1</td>
<td><p><span>Added in: v0.3.1</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>contextifiedSandbox</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a> A <a href="#vm_what_does_it_mean_to_contextify_an_object">contextified</a> object as returned by the
<code>vm.createContext()</code> method.</li>
<li>
<p><code>options</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a></p>
<ul>
<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
by this script.</li>
<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
in stack traces produced by this script.</li>
<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 column number offset that is displayed
in stack traces produced by this script.</li>
<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#errors_class_error"><code>Error</code></a> error occurs
while compiling the <code>code</code>, the line of code causing the error is attached
to the stack trace.</li>
<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>
before terminating execution. If execution is terminated, an <a href="errors.html#errors_class_error"><code>Error</code></a>
will be thrown. This value must be a strictly positive integer.</li>
<li><code>breakOnSigint</code>: if <code>true</code>, the execution will be terminated when
<code>SIGINT</code> (Ctrl+C) is received. Existing handlers for the
event that have been attached via <code>process.on('SIGINT')</code> will be disabled
during script execution, but will continue to work after that.
If execution is terminated, an <a href="errors.html#errors_class_error"><code>Error</code></a> will be thrown.</li>
</ul>
</li>
</ul>
<p>Runs the compiled code contained by the <code>vm.Script</code> object within the given
<code>contextifiedSandbox</code> and returns the result. Running code does not have access
to local scope.</p>
<p>The following example compiles code that increments a global variable, sets
the value of another global variable, then execute the code multiple times.
The globals are contained in the <code>sandbox</code> object.</p>
<pre><code class="language-js"><span class="hljs-keyword">const</span> util = <span class="hljs-built_in">require</span>(<span class="hljs-string">'util'</span>);
<span class="hljs-keyword">const</span> vm = <span class="hljs-built_in">require</span>(<span class="hljs-string">'vm'</span>);
<span class="hljs-keyword">const</span> sandbox = {
<span class="hljs-attr">animal</span>: <span class="hljs-string">'cat'</span>,
<span class="hljs-attr">count</span>: <span class="hljs-number">2</span>
};
<span class="hljs-keyword">const</span> script = <span class="hljs-keyword">new</span> vm.Script(<span class="hljs-string">'count += 1; name = "kitty";'</span>);
<span class="hljs-keyword">const</span> context = vm.createContext(sandbox);
<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) {
script.runInContext(context);
}
<span class="hljs-built_in">console</span>.log(util.inspect(sandbox));
<span class="hljs-comment">// { animal: 'cat', count: 12, name: 'kitty' }</span></code></pre>
<p>Using the <code>timeout</code> or <code>breakOnSigint</code> options will result in new event loops
and corresponding threads being started, which have a non-zero performance
overhead.</p>
<h3>script.runInNewContext([sandbox[, options]])<a class="srclink" href="https://github.com/runkitdev/node/blob/cf1ce2bcc1a88ef6ff1bf745a19913a69607fb02/lib/vm.js#L137">[src]</a><span><a class="mark" href="#vm_script_runinnewcontext_sandbox_options" id="vm_script_runinnewcontext_sandbox_options">#</a></span></h3>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v10.0.0</td>
<td><p>The <code>contextCodeGeneration</code> option is supported now.</p></td></tr>
<tr><td>v0.3.1</td>
<td><p><span>Added in: v0.3.1</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>sandbox</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="#vm_what_does_it_mean_to_contextify_an_object">contextified</a>. If <code>undefined</code>, a
new object will be created.</li>
<li>
<p><code>options</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a></p>
<ul>
<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
by this script.</li>
<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
in stack traces produced by this script.</li>
<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 column number offset that is displayed
in stack traces produced by this script.</li>
<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#errors_class_error"><code>Error</code></a> error occurs
while compiling the <code>code</code>, the line of code causing the error is attached
to the stack trace.</li>
<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>
before terminating execution. If execution is terminated, an <a href="errors.html#errors_class_error"><code>Error</code></a>
will be thrown. This value must be a strictly positive integer.</li>
<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.
<strong>Default:</strong> <code>'VM Context i'</code>, where <code>i</code> is an ascending numerical index of
the created context.</li>
<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
created context for display purposes. The origin should be formatted like a
URL, but with only the scheme, host, and port (if necessary), like the
value of the <a href="url.html#url_url_origin"><code>url.origin</code></a> property of a <a href="url.html#url_class_url"><code>URL</code></a> object. Most notably,
this string should omit the trailing slash, as that denotes a path.
<strong>Default:</strong> <code>''</code>.</li>
<li>
<p><code>contextCodeGeneration</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a></p>
<ul>
<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
constructors (<code>Function</code>, <code>GeneratorFunction</code>, etc) will throw an
<code>EvalError</code>. <strong>Default:</strong> <code>true</code>.</li>
<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
module will throw a <code>WebAssembly.CompileError</code>. <strong>Default:</strong> <code>true</code>.</li>
</ul>
</li>
</ul>
</li>
</ul>
<p>First contextifies the given <code>sandbox</code>, runs the compiled code contained by
the <code>vm.Script</code> object within the created sandbox, and returns the result.
Running code does not have access to local scope.</p>
<p>The following example compiles code that sets a global variable, then executes
the code multiple times in different contexts. The globals are set on and
contained within each individual <code>sandbox</code>.</p>
<pre><code class="language-js"><span class="hljs-keyword">const</span> util = <span class="hljs-built_in">require</span>(<span class="hljs-string">'util'</span>);
<span class="hljs-keyword">const</span> vm = <span class="hljs-built_in">require</span>(<span class="hljs-string">'vm'</span>);
<span class="hljs-keyword">const</span> script = <span class="hljs-keyword">new</span> vm.Script(<span class="hljs-string">'globalVar = "set"'</span>);
<span class="hljs-keyword">const</span> sandboxes = [{}, {}, {}];
sandboxes.forEach(<span class="hljs-function">(<span class="hljs-params">sandbox</span>) =></span> {
script.runInNewContext(sandbox);
});
<span class="hljs-built_in">console</span>.log(util.inspect(sandboxes));
<span class="hljs-comment">// [{ globalVar: 'set' }, { globalVar: 'set' }, { globalVar: 'set' }]</span></code></pre>
<h3>script.runInThisContext([options])<a class="srclink" href="https://github.com/runkitdev/node/blob/cf1ce2bcc1a88ef6ff1bf745a19913a69607fb02/lib/vm.js#L117">[src]</a><span><a class="mark" href="#vm_script_runinthiscontext_options" id="vm_script_runinthiscontext_options">#</a></span></h3>
<div class="api_metadata">
<span>Added in: v0.3.1</span>
</div>
<ul>
<li>
<p><code>options</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a></p>
<ul>
<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
by this script.</li>
<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
in stack traces produced by this script.</li>
<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 column number offset that is displayed
in stack traces produced by this script.</li>
<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#errors_class_error"><code>Error</code></a> error occurs
while compiling the <code>code</code>, the line of code causing the error is attached
to the stack trace.</li>
<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>
before terminating execution. If execution is terminated, an <a href="errors.html#errors_class_error"><code>Error</code></a>
will be thrown. This value must be a strictly positive integer.</li>
</ul>
</li>
</ul>
<p>Runs the compiled code contained by the <code>vm.Script</code> within the context of the
current <code>global</code> object. Running code does not have access to local scope, but
<em>does</em> have access to the current <code>global</code> object.</p>
<p>The following example compiles code that increments a <code>global</code> variable then
executes that code multiple times:</p>
<pre><code class="language-js"><span class="hljs-keyword">const</span> vm = <span class="hljs-built_in">require</span>(<span class="hljs-string">'vm'</span>);
global.globalVar = <span class="hljs-number">0</span>;
<span class="hljs-keyword">const</span> script = <span class="hljs-keyword">new</span> vm.Script(<span class="hljs-string">'globalVar += 1'</span>, { <span class="hljs-attr">filename</span>: <span class="hljs-string">'myfile.vm'</span> });
<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) {
script.runInThisContext();
}
<span class="hljs-built_in">console</span>.log(globalVar);
<span class="hljs-comment">// 1000</span></code></pre>
<h2>vm.compileFunction(code[, params[, options]])<a class="srclink" href="https://github.com/runkitdev/node/blob/cf1ce2bcc1a88ef6ff1bf745a19913a69607fb02/lib/vm.js#L322">[src]</a><span><a class="mark" href="#vm_vm_compilefunction_code_params_options" id="vm_vm_compilefunction_code_params_options">#</a></span></h2>
<div class="api_metadata">
<span>Added in: v10.10.0</span>
</div>
<ul>
<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>
<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
function.</li>
<li>
<p><code>options</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a></p>
<ul>
<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
by this script. <strong>Default:</strong> <code>''</code>.</li>
<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
in stack traces produced by this script. <strong>Default:</strong> <code>0</code>.</li>
<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 column number offset that is displayed
in stack traces produced by this script. <strong>Default:</strong> <code>0</code>.</li>
<li><code>cachedData</code> <a href="buffer.html#buffer_class_buffer" class="type"><Buffer></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/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
<code>TypedArray</code>, or <code>DataView</code> with V8's code cache data for the supplied
source.</li>
<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.
<strong>Default:</strong> <code>false</code>.</li>
<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="#vm_what_does_it_mean_to_contextify_an_object">contextified</a> sandbox in which the said
function should be compiled in.</li>
<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
extensions (objects wrapping the current scope) to be applied while
compiling. <strong>Default:</strong> <code>[]</code>.</li>
</ul>
</li>
</ul>
<p>Compiles the given code into the provided context/sandbox (if no context is
supplied, the current context is used), and returns it wrapped inside a
function with the given <code>params</code>.</p>
<h2>vm.createContext([sandbox[, options]])<a class="srclink" href="https://github.com/runkitdev/node/blob/cf1ce2bcc1a88ef6ff1bf745a19913a69607fb02/lib/vm.js#L233">[src]</a><span><a class="mark" href="#vm_vm_createcontext_sandbox_options" id="vm_vm_createcontext_sandbox_options">#</a></span></h2>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v10.0.0</td>
<td><p>The <code>sandbox</code> option can no longer be a function.</p></td></tr>
<tr><td>v10.0.0</td>
<td><p>The <code>codeGeneration</code> option is supported now.</p></td></tr>
<tr><td>v0.3.1</td>
<td><p><span>Added in: v0.3.1</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>sandbox</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a></li>
<li>
<p><code>options</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a></p>
<ul>
<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.
<strong>Default:</strong> <code>'VM Context i'</code>, where <code>i</code> is an ascending numerical index of
the created context.</li>
<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
context for display purposes. The origin should be formatted like a URL,
but with only the scheme, host, and port (if necessary), like the value of
the <a href="url.html#url_url_origin"><code>url.origin</code></a> property of a <a href="url.html#url_class_url"><code>URL</code></a> object. Most notably, this
string should omit the trailing slash, as that denotes a path.
<strong>Default:</strong> <code>''</code>.</li>
<li>
<p><code>codeGeneration</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a></p>
<ul>
<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
constructors (<code>Function</code>, <code>GeneratorFunction</code>, etc) will throw an
<code>EvalError</code>. <strong>Default:</strong> <code>true</code>.</li>
<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
module will throw a <code>WebAssembly.CompileError</code>. <strong>Default:</strong> <code>true</code>.</li>
</ul>
</li>
</ul>
</li>
</ul>
<p>If given a <code>sandbox</code> object, the <code>vm.createContext()</code> method will <a href="#vm_what_does_it_mean_to_contextify_an_object">prepare
that sandbox</a> so that it can be used in calls to
<a href="#vm_vm_runincontext_code_contextifiedsandbox_options"><code>vm.runInContext()</code></a> or <a href="#vm_script_runincontext_contextifiedsandbox_options"><code>script.runInContext()</code></a>. Inside such scripts,
the <code>sandbox</code> object will be the global object, retaining all of its existing
properties but also having the built-in objects and functions any standard
<a href="https://es5.github.io/#x15.1">global object</a> has. Outside of scripts run by the vm module, global variables
will remain unchanged.</p>
<pre><code class="language-js"><span class="hljs-keyword">const</span> util = <span class="hljs-built_in">require</span>(<span class="hljs-string">'util'</span>);
<span class="hljs-keyword">const</span> vm = <span class="hljs-built_in">require</span>(<span class="hljs-string">'vm'</span>);
global.globalVar = <span class="hljs-number">3</span>;
<span class="hljs-keyword">const</span> sandbox = { <span class="hljs-attr">globalVar</span>: <span class="hljs-number">1</span> };
vm.createContext(sandbox);
vm.runInContext(<span class="hljs-string">'globalVar *= 2;'</span>, sandbox);
<span class="hljs-built_in">console</span>.log(util.inspect(sandbox)); <span class="hljs-comment">// { globalVar: 2 }</span>
<span class="hljs-built_in">console</span>.log(util.inspect(globalVar)); <span class="hljs-comment">// 3</span></code></pre>
<p>If <code>sandbox</code> is omitted (or passed explicitly as <code>undefined</code>), a new, empty
<a href="#vm_what_does_it_mean_to_contextify_an_object">contextified</a> sandbox object will be returned.</p>
<p>The <code>vm.createContext()</code> method is primarily useful for creating a single
sandbox that can be used to run multiple scripts. For instance, if emulating a
web browser, the method can be used to create a single sandbox representing a
window's global object, then run all <code><script></code> tags together within the context
of that sandbox.</p>
<p>The provided <code>name</code> and <code>origin</code> of the context are made visible through the
Inspector API.</p>
<h2>vm.isContext(sandbox)<a class="srclink" href="https://github.com/runkitdev/node/blob/cf1ce2bcc1a88ef6ff1bf745a19913a69607fb02/lib/vm.js#L225">[src]</a><span><a class="mark" href="#vm_vm_iscontext_sandbox" id="vm_vm_iscontext_sandbox">#</a></span></h2>
<div class="api_metadata">
<span>Added in: v0.11.7</span>
</div>
<ul>
<li><code>sandbox</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a></li>
<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type"><boolean></a></li>
</ul>
<p>Returns <code>true</code> if the given <code>sandbox</code> object has been <a href="#vm_what_does_it_mean_to_contextify_an_object">contextified</a> using
<a href="#vm_vm_createcontext_sandbox_options"><code>vm.createContext()</code></a>.</p>
<h2>vm.runInContext(code, contextifiedSandbox[, options])<a class="srclink" href="https://github.com/runkitdev/node/blob/cf1ce2bcc1a88ef6ff1bf745a19913a69607fb02/lib/vm.js#L288">[src]</a><span><a class="mark" href="#vm_vm_runincontext_code_contextifiedsandbox_options" id="vm_vm_runincontext_code_contextifiedsandbox_options">#</a></span></h2>
<ul>
<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>
<li><code>contextifiedSandbox</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a> The <a href="#vm_what_does_it_mean_to_contextify_an_object">contextified</a> object that will be used
as the <code>global</code> when the <code>code</code> is compiled and run.</li>
<li>
<p><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></p>
<ul>
<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
by this script.</li>
<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
in stack traces produced by this script.</li>
<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 column number offset that is displayed
in stack traces produced by this script.</li>
<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#errors_class_error"><code>Error</code></a> error occurs
while compiling the <code>code</code>, the line of code causing the error is attached
to the stack trace.</li>
<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>
before terminating execution. If execution is terminated, an <a href="errors.html#errors_class_error"><code>Error</code></a>
will be thrown. This value must be a strictly positive integer.</li>
</ul>
</li>
</ul>
<p>The <code>vm.runInContext()</code> method compiles <code>code</code>, runs it within the context of
the <code>contextifiedSandbox</code>, then returns the result. Running code does not have
access to the local scope. The <code>contextifiedSandbox</code> object <em>must</em> have been
previously <a href="#vm_what_does_it_mean_to_contextify_an_object">contextified</a> using the <a href="#vm_vm_createcontext_sandbox_options"><code>vm.createContext()</code></a> method.</p>
<p>If <code>options</code> is a string, then it specifies the filename.</p>
<p>The following example compiles and executes different scripts using a single
<a href="#vm_what_does_it_mean_to_contextify_an_object">contextified</a> object:</p>
<pre><code class="language-js"><span class="hljs-keyword">const</span> util = <span class="hljs-built_in">require</span>(<span class="hljs-string">'util'</span>);
<span class="hljs-keyword">const</span> vm = <span class="hljs-built_in">require</span>(<span class="hljs-string">'vm'</span>);
<span class="hljs-keyword">const</span> sandbox = { <span class="hljs-attr">globalVar</span>: <span class="hljs-number">1</span> };
vm.createContext(sandbox);
<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) {
vm.runInContext(<span class="hljs-string">'globalVar *= 2;'</span>, sandbox);
}
<span class="hljs-built_in">console</span>.log(util.inspect(sandbox));
<span class="hljs-comment">// { globalVar: 1024 }</span></code></pre>
<h2>vm.runInNewContext(code[, sandbox[, options]])<a class="srclink" href="https://github.com/runkitdev/node/blob/cf1ce2bcc1a88ef6ff1bf745a19913a69607fb02/lib/vm.js#L304">[src]</a><span><a class="mark" href="#vm_vm_runinnewcontext_code_sandbox_options" id="vm_vm_runinnewcontext_code_sandbox_options">#</a></span></h2>
<div class="api_metadata">
<span>Added in: v0.3.1</span>
</div>
<ul>
<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>
<li><code>sandbox</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="#vm_what_does_it_mean_to_contextify_an_object">contextified</a>. If <code>undefined</code>, a
new object will be created.</li>
<li>
<p><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></p>
<ul>
<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
by this script.</li>
<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
in stack traces produced by this script.</li>
<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 column number offset that is displayed
in stack traces produced by this script.</li>
<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#errors_class_error"><code>Error</code></a> error occurs
while compiling the <code>code</code>, the line of code causing the error is attached
to the stack trace.</li>
<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>
before terminating execution. If execution is terminated, an <a href="errors.html#errors_class_error"><code>Error</code></a>
will be thrown. This value must be a strictly positive integer.</li>
<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.
<strong>Default:</strong> <code>'VM Context i'</code>, where <code>i</code> is an ascending numerical index of
the created context.</li>
<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
created context for display purposes. The origin should be formatted like a
URL, but with only the scheme, host, and port (if necessary), like the
value of the <a href="url.html#url_url_origin"><code>url.origin</code></a> property of a <a href="url.html#url_class_url"><code>URL</code></a> object. Most notably,
this string should omit the trailing slash, as that denotes a path.
<strong>Default:</strong> <code>''</code>.</li>
</ul>
</li>
</ul>
<p>The <code>vm.runInNewContext()</code> first contextifies the given <code>sandbox</code> object (or
creates a new <code>sandbox</code> if passed as <code>undefined</code>), compiles the <code>code</code>, runs it
within the context of the created context, then returns the result. Running code
does not have access to the local scope.</p>
<p>If <code>options</code> is a string, then it specifies the filename.</p>
<p>The following example compiles and executes code that increments a global
variable and sets a new one. These globals are contained in the <code>sandbox</code>.</p>
<pre><code class="language-js"><span class="hljs-keyword">const</span> util = <span class="hljs-built_in">require</span>(<span class="hljs-string">'util'</span>);
<span class="hljs-keyword">const</span> vm = <span class="hljs-built_in">require</span>(<span class="hljs-string">'vm'</span>);
<span class="hljs-keyword">const</span> sandbox = {
<span class="hljs-attr">animal</span>: <span class="hljs-string">'cat'</span>,
<span class="hljs-attr">count</span>: <span class="hljs-number">2</span>
};
vm.runInNewContext(<span class="hljs-string">'count += 1; name = "kitty"'</span>, sandbox);
<span class="hljs-built_in">console</span>.log(util.inspect(sandbox));
<span class="hljs-comment">// { animal: 'cat', count: 3, name: 'kitty' }</span></code></pre>
<h2>vm.runInThisContext(code[, options])<a class="srclink" href="https://github.com/runkitdev/node/blob/cf1ce2bcc1a88ef6ff1bf745a19913a69607fb02/lib/vm.js#L315">[src]</a><span><a class="mark" href="#vm_vm_runinthiscontext_code_options" id="vm_vm_runinthiscontext_code_options">#</a></span></h2>