'`",
"desc": "Specifies the filename used in stack traces produced by this script."
},
{
"textRaw": "`lineOffset` {number} Specifies the line number offset that is displayed in stack traces produced by this script. **Default:** `0`.",
"name": "lineOffset",
"type": "number",
"default": "`0`",
"desc": "Specifies the line number offset that is displayed in stack traces produced by this script."
},
{
"textRaw": "`columnOffset` {number} Specifies the first-line column number offset that is displayed in stack traces produced by this script. **Default:** `0`.",
"name": "columnOffset",
"type": "number",
"default": "`0`",
"desc": "Specifies the first-line column number offset that is displayed in stack traces produced by this script."
},
{
"textRaw": "`cachedData` {Buffer|TypedArray|DataView} Provides an optional `Buffer` or `TypedArray`, or `DataView` with V8's code cache data for the supplied source. When supplied, the `cachedDataRejected` value will be set to either `true` or `false` depending on acceptance of the data by V8.",
"name": "cachedData",
"type": "Buffer|TypedArray|DataView",
"desc": "Provides an optional `Buffer` or `TypedArray`, or `DataView` with V8's code cache data for the supplied source. When supplied, the `cachedDataRejected` value will be set to either `true` or `false` depending on acceptance of the data by V8."
},
{
"textRaw": "`produceCachedData` {boolean} When `true` and no `cachedData` is present, V8 will attempt to produce code cache data for `code`. Upon success, a `Buffer` with V8's code cache data will be produced and stored in the `cachedData` property of the returned `vm.Script` instance. The `cachedDataProduced` value will be set to either `true` or `false` depending on whether code cache data is produced successfully. This option is **deprecated** in favor of `script.createCachedData()`. **Default:** `false`.",
"name": "produceCachedData",
"type": "boolean",
"default": "`false`",
"desc": "When `true` and no `cachedData` is present, V8 will attempt to produce code cache data for `code`. Upon success, a `Buffer` with V8's code cache data will be produced and stored in the `cachedData` property of the returned `vm.Script` instance. The `cachedDataProduced` value will be set to either `true` or `false` depending on whether code cache data is produced successfully. This option is **deprecated** in favor of `script.createCachedData()`."
},
{
"textRaw": "`importModuleDynamically` {Function} Called during evaluation of this module when `import()` is called. If this option is not specified, calls to `import()` will reject with [`ERR_VM_DYNAMIC_IMPORT_CALLBACK_MISSING`][]. This option is part of the experimental modules API. We do not recommend using it in a production environment.",
"name": "importModuleDynamically",
"type": "Function",
"desc": "Called during evaluation of this module when `import()` is called. If this option is not specified, calls to `import()` will reject with [`ERR_VM_DYNAMIC_IMPORT_CALLBACK_MISSING`][]. This option is part of the experimental modules API. We do not recommend using it in a production environment.",
"options": [
{
"textRaw": "`specifier` {string} specifier passed to `import()`",
"name": "specifier",
"type": "string",
"desc": "specifier passed to `import()`"
},
{
"textRaw": "`script` {vm.Script}",
"name": "script",
"type": "vm.Script"
},
{
"textRaw": "`importAssertions` {Object} The `\"assert\"` value passed to the [`optionsExpression`][] optional parameter, or an empty object if no value was provided.",
"name": "importAssertions",
"type": "Object",
"desc": "The `\"assert\"` value passed to the [`optionsExpression`][] optional parameter, or an empty object if no value was provided."
},
{
"textRaw": "Returns: {Module Namespace Object|vm.Module} Returning a `vm.Module` is recommended in order to take advantage of error tracking, and to avoid issues with namespaces that contain `then` function exports.",
"name": "return",
"type": "Module Namespace Object|vm.Module",
"desc": "Returning a `vm.Module` is recommended in order to take advantage of error tracking, and to avoid issues with namespaces that contain `then` function exports."
}
]
}
]
}
],
"desc": "If options
is a string, then it specifies the filename.
\nCreating a new vm.Script
object compiles code
but does not run it. The\ncompiled vm.Script
can be run later multiple times. The code
is not bound to\nany global object; rather, it is bound before each run, just for that run.
"
}
]
},
{
"textRaw": "Class: `vm.Module`",
"type": "class",
"name": "vm.Module",
"meta": {
"added": [
"v13.0.0",
"v12.16.0"
],
"changes": []
},
"stability": 1,
"stabilityText": "Experimental",
"desc": "This feature is only available with the --experimental-vm-modules
command\nflag enabled.
\nThe vm.Module
class provides a low-level interface for using\nECMAScript modules in VM contexts. It is the counterpart of the vm.Script
\nclass that closely mirrors Module Records as defined in the ECMAScript\nspecification.
\nUnlike vm.Script
however, every vm.Module
object is bound to a context from\nits creation. Operations on vm.Module
objects are intrinsically asynchronous,\nin contrast with the synchronous nature of vm.Script
objects. The use of\n'async' functions can help with manipulating vm.Module
objects.
\nUsing a vm.Module
object requires three distinct steps: creation/parsing,\nlinking, and evaluation. These three steps are illustrated in the following\nexample.
\nThis implementation lies at a lower level than the ECMAScript Module\nloader. There is also no way to interact with the Loader yet, though\nsupport is planned.
\nimport vm from 'node:vm';\n\nconst contextifiedObject = vm.createContext({\n secret: 42,\n print: console.log,\n});\n\n// Step 1\n//\n// Create a Module by constructing a new `vm.SourceTextModule` object. This\n// parses the provided source text, throwing a `SyntaxError` if anything goes\n// wrong. By default, a Module is created in the top context. But here, we\n// specify `contextifiedObject` as the context this Module belongs to.\n//\n// Here, we attempt to obtain the default export from the module \"foo\", and\n// put it into local binding \"secret\".\n\nconst bar = new vm.SourceTextModule(`\n import s from 'foo';\n s;\n print(s);\n`, { context: contextifiedObject });\n\n// Step 2\n//\n// \"Link\" the imported dependencies of this Module to it.\n//\n// The provided linking callback (the \"linker\") accepts two arguments: the\n// parent module (`bar` in this case) and the string that is the specifier of\n// the imported module. The callback is expected to return a Module that\n// corresponds to the provided specifier, with certain requirements documented\n// in `module.link()`.\n//\n// If linking has not started for the returned Module, the same linker\n// callback will be called on the returned Module.\n//\n// Even top-level Modules without dependencies must be explicitly linked. The\n// callback provided would never be called, however.\n//\n// The link() method returns a Promise that will be resolved when all the\n// Promises returned by the linker resolve.\n//\n// Note: This is a contrived example in that the linker function creates a new\n// \"foo\" module every time it is called. In a full-fledged module system, a\n// cache would probably be used to avoid duplicated modules.\n\nasync function linker(specifier, referencingModule) {\n if (specifier === 'foo') {\n return new vm.SourceTextModule(`\n // The \"secret\" variable refers to the global variable we added to\n // \"contextifiedObject\" when creating the context.\n export default secret;\n `, { context: referencingModule.context });\n\n // Using `contextifiedObject` instead of `referencingModule.context`\n // here would work as well.\n }\n throw new Error(`Unable to resolve dependency: ${specifier}`);\n}\nawait bar.link(linker);\n\n// Step 3\n//\n// Evaluate the Module. The evaluate() method returns a promise which will\n// resolve after the module has finished evaluating.\n\n// Prints 42.\nawait bar.evaluate();\n
\nconst vm = require('node:vm');\n\nconst contextifiedObject = vm.createContext({\n secret: 42,\n print: console.log,\n});\n\n(async () => {\n // Step 1\n //\n // Create a Module by constructing a new `vm.SourceTextModule` object. This\n // parses the provided source text, throwing a `SyntaxError` if anything goes\n // wrong. By default, a Module is created in the top context. But here, we\n // specify `contextifiedObject` as the context this Module belongs to.\n //\n // Here, we attempt to obtain the default export from the module \"foo\", and\n // put it into local binding \"secret\".\n\n const bar = new vm.SourceTextModule(`\n import s from 'foo';\n s;\n print(s);\n `, { context: contextifiedObject });\n\n // Step 2\n //\n // \"Link\" the imported dependencies of this Module to it.\n //\n // The provided linking callback (the \"linker\") accepts two arguments: the\n // parent module (`bar` in this case) and the string that is the specifier of\n // the imported module. The callback is expected to return a Module that\n // corresponds to the provided specifier, with certain requirements documented\n // in `module.link()`.\n //\n // If linking has not started for the returned Module, the same linker\n // callback will be called on the returned Module.\n //\n // Even top-level Modules without dependencies must be explicitly linked. The\n // callback provided would never be called, however.\n //\n // The link() method returns a Promise that will be resolved when all the\n // Promises returned by the linker resolve.\n //\n // Note: This is a contrived example in that the linker function creates a new\n // \"foo\" module every time it is called. In a full-fledged module system, a\n // cache would probably be used to avoid duplicated modules.\n\n async function linker(specifier, referencingModule) {\n if (specifier === 'foo') {\n return new vm.SourceTextModule(`\n // The \"secret\" variable refers to the global variable we added to\n // \"contextifiedObject\" when creating the context.\n export default secret;\n `, { context: referencingModule.context });\n\n // Using `contextifiedObject` instead of `referencingModule.context`\n // here would work as well.\n }\n throw new Error(`Unable to resolve dependency: ${specifier}`);\n }\n await bar.link(linker);\n\n // Step 3\n //\n // Evaluate the Module. The evaluate() method returns a promise which will\n // resolve after the module has finished evaluating.\n\n // Prints 42.\n await bar.evaluate();\n})();\n
",
"properties": [
{
"textRaw": "`dependencySpecifiers` {string\\[]}",
"type": "string\\[]",
"name": "dependencySpecifiers",
"desc": "The specifiers of all dependencies of this module. The returned array is frozen\nto disallow any changes to it.
\nCorresponds to the [[RequestedModules]]
field of Cyclic Module Records in\nthe ECMAScript specification.
"
},
{
"textRaw": "`error` {any}",
"type": "any",
"name": "error",
"desc": "If the module.status
is 'errored'
, this property contains the exception\nthrown by the module during evaluation. If the status is anything else,\naccessing this property will result in a thrown exception.
\nThe value undefined
cannot be used for cases where there is not a thrown\nexception due to possible ambiguity with throw undefined;
.
\nCorresponds to the [[EvaluationError]]
field of Cyclic Module Records\nin the ECMAScript specification.
"
},
{
"textRaw": "`identifier` {string}",
"type": "string",
"name": "identifier",
"desc": "The identifier of the current module, as set in the constructor.
"
},
{
"textRaw": "`namespace` {Object}",
"type": "Object",
"name": "namespace",
"desc": "The namespace object of the module. This is only available after linking\n(module.link()
) has completed.
\nCorresponds to the GetModuleNamespace abstract operation in the ECMAScript\nspecification.
"
},
{
"textRaw": "`status` {string}",
"type": "string",
"name": "status",
"desc": "The current status of the module. Will be one of:
\n\n- \n
'unlinked'
: module.link()
has not yet been called.
\n \n- \n
'linking'
: module.link()
has been called, but not all Promises returned\nby the linker function have been resolved yet.
\n \n- \n
'linked'
: The module has been linked successfully, and all of its\ndependencies are linked, but module.evaluate()
has not yet been called.
\n \n- \n
'evaluating'
: The module is being evaluated through a module.evaluate()
on\nitself or a parent module.
\n \n- \n
'evaluated'
: The module has been successfully evaluated.
\n \n- \n
'errored'
: The module has been evaluated, but an exception was thrown.
\n \n
\nOther than 'errored'
, this status string corresponds to the specification's\nCyclic Module Record's [[Status]]
field. 'errored'
corresponds to\n'evaluated'
in the specification, but with [[EvaluationError]]
set to a\nvalue that is not undefined
.
"
}
],
"methods": [
{
"textRaw": "`module.evaluate([options])`",
"type": "method",
"name": "evaluate",
"signatures": [
{
"return": {
"textRaw": "Returns: {Promise} Fulfills with `undefined` upon success.",
"name": "return",
"type": "Promise",
"desc": "Fulfills with `undefined` upon success."
},
"params": [
{
"textRaw": "`options` {Object}",
"name": "options",
"type": "Object",
"options": [
{
"textRaw": "`timeout` {integer} Specifies the number of milliseconds to evaluate before terminating execution. If execution is interrupted, an [`Error`][] will be thrown. This value must be a strictly positive integer.",
"name": "timeout",
"type": "integer",
"desc": "Specifies the number of milliseconds to evaluate before terminating execution. If execution is interrupted, an [`Error`][] will be thrown. This value must be a strictly positive integer."
},
{
"textRaw": "`breakOnSigint` {boolean} If `true`, receiving `SIGINT` (Ctrl+C) will terminate execution and throw an [`Error`][]. Existing handlers for the event that have been attached via `process.on('SIGINT')` are disabled during script execution, but continue to work after that. **Default:** `false`.",
"name": "breakOnSigint",
"type": "boolean",
"default": "`false`",
"desc": "If `true`, receiving `SIGINT` (Ctrl+C) will terminate execution and throw an [`Error`][]. Existing handlers for the event that have been attached via `process.on('SIGINT')` are disabled during script execution, but continue to work after that."
}
]
}
]
}
],
"desc": "Evaluate the module.
\nThis must be called after the module has been linked; otherwise it will reject.\nIt could be called also when the module has already been evaluated, in which\ncase it will either do nothing if the initial evaluation ended in success\n(module.status
is 'evaluated'
) or it will re-throw the exception that the\ninitial evaluation resulted in (module.status
is 'errored'
).
\nThis method cannot be called while the module is being evaluated\n(module.status
is 'evaluating'
).
\nCorresponds to the Evaluate() concrete method field of Cyclic Module\nRecords in the ECMAScript specification.
"
},
{
"textRaw": "`module.link(linker)`",
"type": "method",
"name": "link",
"signatures": [
{
"return": {
"textRaw": "Returns: {Promise}",
"name": "return",
"type": "Promise"
},
"params": [
{
"textRaw": "`linker` {Function}",
"name": "linker",
"type": "Function",
"options": [
{
"textRaw": "`specifier` {string} The specifier of the requested module:```mjs import foo from 'foo'; // ^^^^^ the module specifier ```",
"name": "specifier",
"type": "string",
"desc": "The specifier of the requested module:```mjs import foo from 'foo'; // ^^^^^ the module specifier ```"
},
{
"textRaw": "`referencingModule` {vm.Module} The `Module` object `link()` is called on.",
"name": "referencingModule",
"type": "vm.Module",
"desc": "The `Module` object `link()` is called on."
},
{
"textRaw": "`extra` {Object}",
"name": "extra",
"type": "Object",
"options": [
{
"textRaw": "`assert` {Object} The data from the assertion:```js import foo from 'foo' assert { name: 'value' }; // ^^^^^^^^^^^^^^^^^ the assertion ```Per ECMA-262, hosts are expected to ignore assertions that they do not support, as opposed to, for example, triggering an error if an unsupported assertion is present.",
"name": "assert",
"type": "Object",
"desc": "The data from the assertion:```js import foo from 'foo' assert { name: 'value' }; // ^^^^^^^^^^^^^^^^^ the assertion ```Per ECMA-262, hosts are expected to ignore assertions that they do not support, as opposed to, for example, triggering an error if an unsupported assertion is present."
}
]
},
{
"textRaw": "Returns: {vm.Module|Promise}",
"name": "return",
"type": "vm.Module|Promise"
}
]
}
]
}
],
"desc": "Link module dependencies. This method must be called before evaluation, and\ncan only be called once per module.
\nThe function is expected to return a Module
object or a Promise
that\neventually resolves to a Module
object. The returned Module
must satisfy the\nfollowing two invariants:
\n\n- It must belong to the same context as the parent
Module
. \n- Its
status
must not be 'errored'
. \n
\nIf the returned Module
's status
is 'unlinked'
, this method will be\nrecursively called on the returned Module
with the same provided linker
\nfunction.
\nlink()
returns a Promise
that will either get resolved when all linking\ninstances resolve to a valid Module
, or rejected if the linker function either\nthrows an exception or returns an invalid Module
.
\nThe linker function roughly corresponds to the implementation-defined\nHostResolveImportedModule abstract operation in the ECMAScript\nspecification, with a few key differences:
\n\nThe actual HostResolveImportedModule implementation used during module\nlinking is one that returns the modules linked during linking. Since at\nthat point all modules would have been fully linked already, the\nHostResolveImportedModule implementation is fully synchronous per\nspecification.
\nCorresponds to the Link() concrete method field of Cyclic Module\nRecords in the ECMAScript specification.
"
}
]
},
{
"textRaw": "Class: `vm.SourceTextModule`",
"type": "class",
"name": "vm.SourceTextModule",
"meta": {
"added": [
"v9.6.0"
],
"changes": []
},
"stability": 1,
"stabilityText": "Experimental",
"desc": "This feature is only available with the --experimental-vm-modules
command\nflag enabled.
\n\nThe vm.SourceTextModule
class provides the Source Text Module Record as\ndefined in the ECMAScript specification.
",
"methods": [
{
"textRaw": "`sourceTextModule.createCachedData()`",
"type": "method",
"name": "createCachedData",
"meta": {
"added": [
"v13.7.0",
"v12.17.0"
],
"changes": []
},
"signatures": [
{
"return": {
"textRaw": "Returns: {Buffer}",
"name": "return",
"type": "Buffer"
},
"params": []
}
],
"desc": "Creates a code cache that can be used with the SourceTextModule
constructor's\ncachedData
option. Returns a Buffer
. This method may be called any number\nof times before the module has been evaluated.
\nThe code cache of the SourceTextModule
doesn't contain any JavaScript\nobservable states. The code cache is safe to be saved along side the script\nsource and used to construct new SourceTextModule
instances multiple times.
\nFunctions in the SourceTextModule
source can be marked as lazily compiled\nand they are not compiled at construction of the SourceTextModule
. These\nfunctions are going to be compiled when they are invoked the first time. The\ncode cache serializes the metadata that V8 currently knows about the\nSourceTextModule
that it can use to speed up future compilations.
\n// Create an initial module\nconst module = new vm.SourceTextModule('const a = 1;');\n\n// Create cached data from this module\nconst cachedData = module.createCachedData();\n\n// Create a new module using the cached data. The code must be the same.\nconst module2 = new vm.SourceTextModule('const a = 1;', { cachedData });\n
"
}
],
"signatures": [
{
"params": [
{
"textRaw": "`code` {string} JavaScript Module code to parse",
"name": "code",
"type": "string",
"desc": "JavaScript Module code to parse"
},
{
"textRaw": "`options`",
"name": "options",
"options": [
{
"textRaw": "`identifier` {string} String used in stack traces. **Default:** `'vm:module(i)'` where `i` is a context-specific ascending index.",
"name": "identifier",
"type": "string",
"default": "`'vm:module(i)'` where `i` is a context-specific ascending index",
"desc": "String used in stack traces."
},
{
"textRaw": "`cachedData` {Buffer|TypedArray|DataView} Provides an optional `Buffer` or `TypedArray`, or `DataView` with V8's code cache data for the supplied source. The `code` must be the same as the module from which this `cachedData` was created.",
"name": "cachedData",
"type": "Buffer|TypedArray|DataView",
"desc": "Provides an optional `Buffer` or `TypedArray`, or `DataView` with V8's code cache data for the supplied source. The `code` must be the same as the module from which this `cachedData` was created."
},
{
"textRaw": "`context` {Object} The [contextified][] object as returned by the `vm.createContext()` method, to compile and evaluate this `Module` in.",
"name": "context",
"type": "Object",
"desc": "The [contextified][] object as returned by the `vm.createContext()` method, to compile and evaluate this `Module` in."
},
{
"textRaw": "`lineOffset` {integer} Specifies the line number offset that is displayed in stack traces produced by this `Module`. **Default:** `0`.",
"name": "lineOffset",
"type": "integer",
"default": "`0`",
"desc": "Specifies the line number offset that is displayed in stack traces produced by this `Module`."
},
{
"textRaw": "`columnOffset` {integer} Specifies the first-line column number offset that is displayed in stack traces produced by this `Module`. **Default:** `0`.",
"name": "columnOffset",
"type": "integer",
"default": "`0`",
"desc": "Specifies the first-line column number offset that is displayed in stack traces produced by this `Module`."
},
{
"textRaw": "`initializeImportMeta` {Function} Called during evaluation of this `Module` to initialize the `import.meta`.",
"name": "initializeImportMeta",
"type": "Function",
"desc": "Called during evaluation of this `Module` to initialize the `import.meta`.",
"options": [
{
"textRaw": "`meta` {import.meta}",
"name": "meta",
"type": "import.meta"
},
{
"textRaw": "`module` {vm.SourceTextModule}",
"name": "module",
"type": "vm.SourceTextModule"
}
]
},
{
"textRaw": "`importModuleDynamically` {Function} Called during evaluation of this module when `import()` is called. If this option is not specified, calls to `import()` will reject with [`ERR_VM_DYNAMIC_IMPORT_CALLBACK_MISSING`][].",
"name": "importModuleDynamically",
"type": "Function",
"desc": "Called during evaluation of this module when `import()` is called. If this option is not specified, calls to `import()` will reject with [`ERR_VM_DYNAMIC_IMPORT_CALLBACK_MISSING`][].",
"options": [
{
"textRaw": "`specifier` {string} specifier passed to `import()`",
"name": "specifier",
"type": "string",
"desc": "specifier passed to `import()`"
},
{
"textRaw": "`module` {vm.Module}",
"name": "module",
"type": "vm.Module"
},
{
"textRaw": "`importAssertions` {Object} The `\"assert\"` value passed to the [`optionsExpression`][] optional parameter, or an empty object if no value was provided.",
"name": "importAssertions",
"type": "Object",
"desc": "The `\"assert\"` value passed to the [`optionsExpression`][] optional parameter, or an empty object if no value was provided."
},
{
"textRaw": "Returns: {Module Namespace Object|vm.Module} Returning a `vm.Module` is recommended in order to take advantage of error tracking, and to avoid issues with namespaces that contain `then` function exports.",
"name": "return",
"type": "Module Namespace Object|vm.Module",
"desc": "Returning a `vm.Module` is recommended in order to take advantage of error tracking, and to avoid issues with namespaces that contain `then` function exports."
}
]
}
]
}
],
"desc": "Creates a new SourceTextModule
instance.
\nProperties assigned to the import.meta
object that are objects may\nallow the module to access information outside the specified context
. Use\nvm.runInContext()
to create objects in a specific context.
\nimport vm from 'node:vm';\n\nconst contextifiedObject = vm.createContext({ secret: 42 });\n\nconst module = new vm.SourceTextModule(\n 'Object.getPrototypeOf(import.meta.prop).secret = secret;',\n {\n initializeImportMeta(meta) {\n // Note: this object is created in the top context. As such,\n // Object.getPrototypeOf(import.meta.prop) points to the\n // Object.prototype in the top context rather than that in\n // the contextified object.\n meta.prop = {};\n }\n });\n// Since module has no dependencies, the linker function will never be called.\nawait module.link(() => {});\nawait module.evaluate();\n\n// Now, Object.prototype.secret will be equal to 42.\n//\n// To fix this problem, replace\n// meta.prop = {};\n// above with\n// meta.prop = vm.runInContext('{}', contextifiedObject);\n
\nconst vm = require('node:vm');\nconst contextifiedObject = vm.createContext({ secret: 42 });\n(async () => {\n const module = new vm.SourceTextModule(\n 'Object.getPrototypeOf(import.meta.prop).secret = secret;',\n {\n initializeImportMeta(meta) {\n // Note: this object is created in the top context. As such,\n // Object.getPrototypeOf(import.meta.prop) points to the\n // Object.prototype in the top context rather than that in\n // the contextified object.\n meta.prop = {};\n }\n });\n // Since module has no dependencies, the linker function will never be called.\n await module.link(() => {});\n await module.evaluate();\n // Now, Object.prototype.secret will be equal to 42.\n //\n // To fix this problem, replace\n // meta.prop = {};\n // above with\n // meta.prop = vm.runInContext('{}', contextifiedObject);\n})();\n
"
}
]
},
{
"textRaw": "Class: `vm.SyntheticModule`",
"type": "class",
"name": "vm.SyntheticModule",
"meta": {
"added": [
"v13.0.0",
"v12.16.0"
],
"changes": []
},
"stability": 1,
"stabilityText": "Experimental",
"desc": "This feature is only available with the --experimental-vm-modules
command\nflag enabled.
\n\nThe vm.SyntheticModule
class provides the Synthetic Module Record as\ndefined in the WebIDL specification. The purpose of synthetic modules is to\nprovide a generic interface for exposing non-JavaScript sources to ECMAScript\nmodule graphs.
\nconst vm = require('node:vm');\n\nconst source = '{ \"a\": 1 }';\nconst module = new vm.SyntheticModule(['default'], function() {\n const obj = JSON.parse(source);\n this.setExport('default', obj);\n});\n\n// Use `module` in linking...\n
",
"methods": [
{
"textRaw": "`syntheticModule.setExport(name, value)`",
"type": "method",
"name": "setExport",
"meta": {
"added": [
"v13.0.0",
"v12.16.0"
],
"changes": []
},
"signatures": [
{
"params": [
{
"textRaw": "`name` {string} Name of the export to set.",
"name": "name",
"type": "string",
"desc": "Name of the export to set."
},
{
"textRaw": "`value` {any} The value to set the export to.",
"name": "value",
"type": "any",
"desc": "The value to set the export to."
}
]
}
],
"desc": "This method is used after the module is linked to set the values of exports. If\nit is called before the module is linked, an ERR_VM_MODULE_STATUS
error\nwill be thrown.
\nimport vm from 'node:vm';\n\nconst m = new vm.SyntheticModule(['x'], () => {\n m.setExport('x', 1);\n});\n\nawait m.link(() => {});\nawait m.evaluate();\n\nassert.strictEqual(m.namespace.x, 1);\n
\nconst vm = require('node:vm');\n(async () => {\n const m = new vm.SyntheticModule(['x'], () => {\n m.setExport('x', 1);\n });\n await m.link(() => {});\n await m.evaluate();\n assert.strictEqual(m.namespace.x, 1);\n})();\n
"
}
],
"signatures": [
{
"params": [
{
"textRaw": "`exportNames` {string\\[]} Array of names that will be exported from the module.",
"name": "exportNames",
"type": "string\\[]",
"desc": "Array of names that will be exported from the module."
},
{
"textRaw": "`evaluateCallback` {Function} Called when the module is evaluated.",
"name": "evaluateCallback",
"type": "Function",
"desc": "Called when the module is evaluated."
},
{
"textRaw": "`options`",
"name": "options",
"options": [
{
"textRaw": "`identifier` {string} String used in stack traces. **Default:** `'vm:module(i)'` where `i` is a context-specific ascending index.",
"name": "identifier",
"type": "string",
"default": "`'vm:module(i)'` where `i` is a context-specific ascending index",
"desc": "String used in stack traces."
},
{
"textRaw": "`context` {Object} The [contextified][] object as returned by the `vm.createContext()` method, to compile and evaluate this `Module` in.",
"name": "context",
"type": "Object",
"desc": "The [contextified][] object as returned by the `vm.createContext()` method, to compile and evaluate this `Module` in."
}
]
}
],
"desc": "Creates a new SyntheticModule
instance.
\nObjects assigned to the exports of this instance may allow importers of\nthe module to access information outside the specified context
. Use\nvm.runInContext()
to create objects in a specific context.
"
}
]
}
],
"methods": [
{
"textRaw": "`vm.compileFunction(code[, params[, options]])`",
"type": "method",
"name": "compileFunction",
"meta": {
"added": [
"v10.10.0"
],
"changes": [
{
"version": "v16.12.0",
"pr-url": "https://github.com/nodejs/node/pull/40249",
"description": "Added support for import assertions to the `importModuleDynamically` parameter."
},
{
"version": "v15.9.0",
"pr-url": "https://github.com/nodejs/node/pull/35431",
"description": "Added `importModuleDynamically` option again."
},
{
"version": "v14.3.0",
"pr-url": "https://github.com/nodejs/node/pull/33364",
"description": "Removal of `importModuleDynamically` due to compatibility issues."
},
{
"version": [
"v14.1.0",
"v13.14.0"
],
"pr-url": "https://github.com/nodejs/node/pull/32985",
"description": "The `importModuleDynamically` option is now supported."
}
]
},
"signatures": [
{
"return": {
"textRaw": "Returns: {Function}",
"name": "return",
"type": "Function"
},
"params": [
{
"textRaw": "`code` {string} The body of the function to compile.",
"name": "code",
"type": "string",
"desc": "The body of the function to compile."
},
{
"textRaw": "`params` {string\\[]} An array of strings containing all parameters for the function.",
"name": "params",
"type": "string\\[]",
"desc": "An array of strings containing all parameters for the function."
},
{
"textRaw": "`options` {Object}",
"name": "options",
"type": "Object",
"options": [
{
"textRaw": "`filename` {string} Specifies the filename used in stack traces produced by this script. **Default:** `''`.",
"name": "filename",
"type": "string",
"default": "`''`",
"desc": "Specifies the filename used in stack traces produced by this script."
},
{
"textRaw": "`lineOffset` {number} Specifies the line number offset that is displayed in stack traces produced by this script. **Default:** `0`.",
"name": "lineOffset",
"type": "number",
"default": "`0`",
"desc": "Specifies the line number offset that is displayed in stack traces produced by this script."
},
{
"textRaw": "`columnOffset` {number} Specifies the first-line column number offset that is displayed in stack traces produced by this script. **Default:** `0`.",
"name": "columnOffset",
"type": "number",
"default": "`0`",
"desc": "Specifies the first-line column number offset that is displayed in stack traces produced by this script."
},
{
"textRaw": "`cachedData` {Buffer|TypedArray|DataView} Provides an optional `Buffer` or `TypedArray`, or `DataView` with V8's code cache data for the supplied source.",
"name": "cachedData",
"type": "Buffer|TypedArray|DataView",
"desc": "Provides an optional `Buffer` or `TypedArray`, or `DataView` with V8's code cache data for the supplied source."
},
{
"textRaw": "`produceCachedData` {boolean} Specifies whether to produce new cache data. **Default:** `false`.",
"name": "produceCachedData",
"type": "boolean",
"default": "`false`",
"desc": "Specifies whether to produce new cache data."
},
{
"textRaw": "`parsingContext` {Object} The [contextified][] object in which the said function should be compiled in.",
"name": "parsingContext",
"type": "Object",
"desc": "The [contextified][] object in which the said function should be compiled in."
},
{
"textRaw": "`contextExtensions` {Object\\[]} An array containing a collection of context extensions (objects wrapping the current scope) to be applied while compiling. **Default:** `[]`.",
"name": "contextExtensions",
"type": "Object\\[]",
"default": "`[]`",
"desc": "An array containing a collection of context extensions (objects wrapping the current scope) to be applied while compiling."
},
{
"textRaw": "`importModuleDynamically` {Function} Called during evaluation of this module when `import()` is called. If this option is not specified, calls to `import()` will reject with [`ERR_VM_DYNAMIC_IMPORT_CALLBACK_MISSING`][]. This option is part of the experimental modules API, and should not be considered stable.",
"name": "importModuleDynamically",
"type": "Function",
"desc": "Called during evaluation of this module when `import()` is called. If this option is not specified, calls to `import()` will reject with [`ERR_VM_DYNAMIC_IMPORT_CALLBACK_MISSING`][]. This option is part of the experimental modules API, and should not be considered stable.",
"options": [
{
"textRaw": "`specifier` {string} specifier passed to `import()`",
"name": "specifier",
"type": "string",
"desc": "specifier passed to `import()`"
},
{
"textRaw": "`function` {Function}",
"name": "function",
"type": "Function"
},
{
"textRaw": "`importAssertions` {Object} The `\"assert\"` value passed to the [`optionsExpression`][] optional parameter, or an empty object if no value was provided.",
"name": "importAssertions",
"type": "Object",
"desc": "The `\"assert\"` value passed to the [`optionsExpression`][] optional parameter, or an empty object if no value was provided."
},
{
"textRaw": "Returns: {Module Namespace Object|vm.Module} Returning a `vm.Module` is recommended in order to take advantage of error tracking, and to avoid issues with namespaces that contain `then` function exports.",
"name": "return",
"type": "Module Namespace Object|vm.Module",
"desc": "Returning a `vm.Module` is recommended in order to take advantage of error tracking, and to avoid issues with namespaces that contain `then` function exports."
}
]
}
]
}
]
}
],
"desc": "Compiles the given code into the provided context (if no context is\nsupplied, the current context is used), and returns it wrapped inside a\nfunction with the given params
.
"
},
{
"textRaw": "`vm.createContext([contextObject[, options]])`",
"type": "method",
"name": "createContext",
"meta": {
"added": [
"v0.3.1"
],
"changes": [
{
"version": "v14.6.0",
"pr-url": "https://github.com/nodejs/node/pull/34023",
"description": "The `microtaskMode` option is supported now."
},
{
"version": "v10.0.0",
"pr-url": "https://github.com/nodejs/node/pull/19398",
"description": "The first argument can no longer be a function."
},
{
"version": "v10.0.0",
"pr-url": "https://github.com/nodejs/node/pull/19016",
"description": "The `codeGeneration` option is supported now."
}
]
},
"signatures": [
{
"return": {
"textRaw": "Returns: {Object} contextified object.",
"name": "return",
"type": "Object",
"desc": "contextified object."
},
"params": [
{
"textRaw": "`contextObject` {Object}",
"name": "contextObject",
"type": "Object"
},
{
"textRaw": "`options` {Object}",
"name": "options",
"type": "Object",
"options": [
{
"textRaw": "`name` {string} Human-readable name of the newly created context. **Default:** `'VM Context i'`, where `i` is an ascending numerical index of the created context.",
"name": "name",
"type": "string",
"default": "`'VM Context i'`, where `i` is an ascending numerical index of the created context",
"desc": "Human-readable name of the newly created context."
},
{
"textRaw": "`origin` {string} [Origin][origin] 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 [`url.origin`][] property of a [`URL`][] object. Most notably, this string should omit the trailing slash, as that denotes a path. **Default:** `''`.",
"name": "origin",
"type": "string",
"default": "`''`",
"desc": "[Origin][origin] 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 [`url.origin`][] property of a [`URL`][] object. Most notably, this string should omit the trailing slash, as that denotes a path."
},
{
"textRaw": "`codeGeneration` {Object}",
"name": "codeGeneration",
"type": "Object",
"options": [
{
"textRaw": "`strings` {boolean} If set to false any calls to `eval` or function constructors (`Function`, `GeneratorFunction`, etc) will throw an `EvalError`. **Default:** `true`.",
"name": "strings",
"type": "boolean",
"default": "`true`",
"desc": "If set to false any calls to `eval` or function constructors (`Function`, `GeneratorFunction`, etc) will throw an `EvalError`."
},
{
"textRaw": "`wasm` {boolean} If set to false any attempt to compile a WebAssembly module will throw a `WebAssembly.CompileError`. **Default:** `true`.",
"name": "wasm",
"type": "boolean",
"default": "`true`",
"desc": "If set to false any attempt to compile a WebAssembly module will throw a `WebAssembly.CompileError`."
}
]
},
{
"textRaw": "`microtaskMode` {string} If set to `afterEvaluate`, microtasks (tasks scheduled through `Promise`s and `async function`s) will be run immediately after a script has run through [`script.runInContext()`][]. They are included in the `timeout` and `breakOnSigint` scopes in that case.",
"name": "microtaskMode",
"type": "string",
"desc": "If set to `afterEvaluate`, microtasks (tasks scheduled through `Promise`s and `async function`s) will be run immediately after a script has run through [`script.runInContext()`][]. They are included in the `timeout` and `breakOnSigint` scopes in that case."
}
]
}
]
}
],
"desc": "If given a contextObject
, the vm.createContext()
method will prepare\nthat object so that it can be used in calls to\nvm.runInContext()
or script.runInContext()
. Inside such scripts,\nthe contextObject
will be the global object, retaining all of its existing\nproperties but also having the built-in objects and functions any standard\nglobal object has. Outside of scripts run by the vm module, global variables\nwill remain unchanged.
\nconst vm = require('node:vm');\n\nglobal.globalVar = 3;\n\nconst context = { globalVar: 1 };\nvm.createContext(context);\n\nvm.runInContext('globalVar *= 2;', context);\n\nconsole.log(context);\n// Prints: { globalVar: 2 }\n\nconsole.log(global.globalVar);\n// Prints: 3\n
\nIf contextObject
is omitted (or passed explicitly as undefined
), a new,\nempty contextified object will be returned.
\nThe vm.createContext()
method is primarily useful for creating a single\ncontext that can be used to run multiple scripts. For instance, if emulating a\nweb browser, the method can be used to create a single context representing a\nwindow's global object, then run all <script>
tags together within that\ncontext.
\nThe provided name
and origin
of the context are made visible through the\nInspector API.
"
},
{
"textRaw": "`vm.isContext(object)`",
"type": "method",
"name": "isContext",
"meta": {
"added": [
"v0.11.7"
],
"changes": []
},
"signatures": [
{
"return": {
"textRaw": "Returns: {boolean}",
"name": "return",
"type": "boolean"
},
"params": [
{
"textRaw": "`object` {Object}",
"name": "object",
"type": "Object"
}
]
}
],
"desc": "Returns true
if the given object
object has been contextified using\nvm.createContext()
.
"
},
{
"textRaw": "`vm.measureMemory([options])`",
"type": "method",
"name": "measureMemory",
"meta": {
"added": [
"v13.10.0"
],
"changes": []
},
"stability": 1,
"stabilityText": "Experimental",
"signatures": [
{
"params": []
}
],
"desc": "Measure the memory known to V8 and used by all contexts known to the\ncurrent V8 isolate, or the main context.
\n\noptions
<Object> Optional.\n\nmode
<string> Either 'summary'
or 'detailed'
. In summary mode,\nonly the memory measured for the main context will be returned. In\ndetailed mode, the memory measured for all contexts known to the\ncurrent V8 isolate will be returned.\nDefault: 'summary'
\nexecution
<string> Either 'default'
or 'eager'
. With default\nexecution, the promise will not resolve until after the next scheduled\ngarbage collection starts, which may take a while (or never if the program\nexits before the next GC). With eager execution, the GC will be started\nright away to measure the memory.\nDefault: 'default'
\n
\n \n- Returns: <Promise> If the memory is successfully measured the promise will\nresolve with an object containing information about the memory usage.
\n
\nThe format of the object that the returned Promise may resolve with is\nspecific to the V8 engine and may change from one version of V8 to the next.
\nThe returned result is different from the statistics returned by\nv8.getHeapSpaceStatistics()
in that vm.measureMemory()
measure the\nmemory reachable by each V8 specific contexts in the current instance of\nthe V8 engine, while the result of v8.getHeapSpaceStatistics()
measure\nthe memory occupied by each heap space in the current V8 instance.
\nconst vm = require('node:vm');\n// Measure the memory used by the main context.\nvm.measureMemory({ mode: 'summary' })\n // This is the same as vm.measureMemory()\n .then((result) => {\n // The current format is:\n // {\n // total: {\n // jsMemoryEstimate: 2418479, jsMemoryRange: [ 2418479, 2745799 ]\n // }\n // }\n console.log(result);\n });\n\nconst context = vm.createContext({ a: 1 });\nvm.measureMemory({ mode: 'detailed', execution: 'eager' })\n .then((result) => {\n // Reference the context here so that it won't be GC'ed\n // until the measurement is complete.\n console.log(context.a);\n // {\n // total: {\n // jsMemoryEstimate: 2574732,\n // jsMemoryRange: [ 2574732, 2904372 ]\n // },\n // current: {\n // jsMemoryEstimate: 2438996,\n // jsMemoryRange: [ 2438996, 2768636 ]\n // },\n // other: [\n // {\n // jsMemoryEstimate: 135736,\n // jsMemoryRange: [ 135736, 465376 ]\n // }\n // ]\n // }\n console.log(result);\n });\n
"
},
{
"textRaw": "`vm.runInContext(code, contextifiedObject[, options])`",
"type": "method",
"name": "runInContext",
"meta": {
"added": [
"v0.3.1"
],
"changes": [
{
"version": "v16.12.0",
"pr-url": "https://github.com/nodejs/node/pull/40249",
"description": "Added support for import assertions to the `importModuleDynamically` parameter."
},
{
"version": "v6.3.0",
"pr-url": "https://github.com/nodejs/node/pull/6635",
"description": "The `breakOnSigint` option is supported now."
}
]
},
"signatures": [
{
"return": {
"textRaw": "Returns: {any} the result of the very last statement executed in the script.",
"name": "return",
"type": "any",
"desc": "the result of the very last statement executed in the script."
},
"params": [
{
"textRaw": "`code` {string} The JavaScript code to compile and run.",
"name": "code",
"type": "string",
"desc": "The JavaScript code to compile and run."
},
{
"textRaw": "`contextifiedObject` {Object} The [contextified][] object that will be used as the `global` when the `code` is compiled and run.",
"name": "contextifiedObject",
"type": "Object",
"desc": "The [contextified][] object that will be used as the `global` when the `code` is compiled and run."
},
{
"textRaw": "`options` {Object|string}",
"name": "options",
"type": "Object|string",
"options": [
{
"textRaw": "`filename` {string} Specifies the filename used in stack traces produced by this script. **Default:** `'evalmachine.'`.",
"name": "filename",
"type": "string",
"default": "`'evalmachine.'`",
"desc": "Specifies the filename used in stack traces produced by this script."
},
{
"textRaw": "`lineOffset` {number} Specifies the line number offset that is displayed in stack traces produced by this script. **Default:** `0`.",
"name": "lineOffset",
"type": "number",
"default": "`0`",
"desc": "Specifies the line number offset that is displayed in stack traces produced by this script."
},
{
"textRaw": "`columnOffset` {number} Specifies the first-line column number offset that is displayed in stack traces produced by this script. **Default:** `0`.",
"name": "columnOffset",
"type": "number",
"default": "`0`",
"desc": "Specifies the first-line column number offset that is displayed in stack traces produced by this script."
},
{
"textRaw": "`displayErrors` {boolean} When `true`, if an [`Error`][] occurs while compiling the `code`, the line of code causing the error is attached to the stack trace. **Default:** `true`.",
"name": "displayErrors",
"type": "boolean",
"default": "`true`",
"desc": "When `true`, if an [`Error`][] occurs while compiling the `code`, the line of code causing the error is attached to the stack trace."
},
{
"textRaw": "`timeout` {integer} Specifies the number of milliseconds to execute `code` before terminating execution. If execution is terminated, an [`Error`][] will be thrown. This value must be a strictly positive integer.",
"name": "timeout",
"type": "integer",
"desc": "Specifies the number of milliseconds to execute `code` before terminating execution. If execution is terminated, an [`Error`][] will be thrown. This value must be a strictly positive integer."
},
{
"textRaw": "`breakOnSigint` {boolean} If `true`, receiving `SIGINT` (Ctrl+C) will terminate execution and throw an [`Error`][]. Existing handlers for the event that have been attached via `process.on('SIGINT')` are disabled during script execution, but continue to work after that. **Default:** `false`.",
"name": "breakOnSigint",
"type": "boolean",
"default": "`false`",
"desc": "If `true`, receiving `SIGINT` (Ctrl+C) will terminate execution and throw an [`Error`][]. Existing handlers for the event that have been attached via `process.on('SIGINT')` are disabled during script execution, but continue to work after that."
},
{
"textRaw": "`cachedData` {Buffer|TypedArray|DataView} Provides an optional `Buffer` or `TypedArray`, or `DataView` with V8's code cache data for the supplied source.",
"name": "cachedData",
"type": "Buffer|TypedArray|DataView",
"desc": "Provides an optional `Buffer` or `TypedArray`, or `DataView` with V8's code cache data for the supplied source."
},
{
"textRaw": "`importModuleDynamically` {Function} Called during evaluation of this module when `import()` is called. If this option is not specified, calls to `import()` will reject with [`ERR_VM_DYNAMIC_IMPORT_CALLBACK_MISSING`][]. This option is part of the experimental modules API. We do not recommend using it in a production environment.",
"name": "importModuleDynamically",
"type": "Function",
"desc": "Called during evaluation of this module when `import()` is called. If this option is not specified, calls to `import()` will reject with [`ERR_VM_DYNAMIC_IMPORT_CALLBACK_MISSING`][]. This option is part of the experimental modules API. We do not recommend using it in a production environment.",
"options": [
{
"textRaw": "`specifier` {string} specifier passed to `import()`",
"name": "specifier",
"type": "string",
"desc": "specifier passed to `import()`"
},
{
"textRaw": "`script` {vm.Script}",
"name": "script",
"type": "vm.Script"
},
{
"textRaw": "`importAssertions` {Object} The `\"assert\"` value passed to the [`optionsExpression`][] optional parameter, or an empty object if no value was provided.",
"name": "importAssertions",
"type": "Object",
"desc": "The `\"assert\"` value passed to the [`optionsExpression`][] optional parameter, or an empty object if no value was provided."
},
{
"textRaw": "Returns: {Module Namespace Object|vm.Module} Returning a `vm.Module` is recommended in order to take advantage of error tracking, and to avoid issues with namespaces that contain `then` function exports.",
"name": "return",
"type": "Module Namespace Object|vm.Module",
"desc": "Returning a `vm.Module` is recommended in order to take advantage of error tracking, and to avoid issues with namespaces that contain `then` function exports."
}
]
}
]
}
]
}
],
"desc": "The vm.runInContext()
method compiles code
, runs it within the context of\nthe contextifiedObject
, then returns the result. Running code does not have\naccess to the local scope. The contextifiedObject
object must have been\npreviously contextified using the vm.createContext()
method.
\nIf options
is a string, then it specifies the filename.
\nThe following example compiles and executes different scripts using a single\ncontextified object:
\nconst vm = require('node:vm');\n\nconst contextObject = { globalVar: 1 };\nvm.createContext(contextObject);\n\nfor (let i = 0; i < 10; ++i) {\n vm.runInContext('globalVar *= 2;', contextObject);\n}\nconsole.log(contextObject);\n// Prints: { globalVar: 1024 }\n
"
},
{
"textRaw": "`vm.runInNewContext(code[, contextObject[, options]])`",
"type": "method",
"name": "runInNewContext",
"meta": {
"added": [
"v0.3.1"
],
"changes": [
{
"version": "v16.12.0",
"pr-url": "https://github.com/nodejs/node/pull/40249",
"description": "Added support for import assertions to the `importModuleDynamically` parameter."
},
{
"version": "v14.6.0",
"pr-url": "https://github.com/nodejs/node/pull/34023",
"description": "The `microtaskMode` option is supported now."
},
{
"version": "v10.0.0",
"pr-url": "https://github.com/nodejs/node/pull/19016",
"description": "The `contextCodeGeneration` option is supported now."
},
{
"version": "v6.3.0",
"pr-url": "https://github.com/nodejs/node/pull/6635",
"description": "The `breakOnSigint` option is supported now."
}
]
},
"signatures": [
{
"return": {
"textRaw": "Returns: {any} the result of the very last statement executed in the script.",
"name": "return",
"type": "any",
"desc": "the result of the very last statement executed in the script."
},
"params": [
{
"textRaw": "`code` {string} The JavaScript code to compile and run.",
"name": "code",
"type": "string",
"desc": "The JavaScript code to compile and run."
},
{
"textRaw": "`contextObject` {Object} An object that will be [contextified][]. If `undefined`, a new object will be created.",
"name": "contextObject",
"type": "Object",
"desc": "An object that will be [contextified][]. If `undefined`, a new object will be created."
},
{
"textRaw": "`options` {Object|string}",
"name": "options",
"type": "Object|string",
"options": [
{
"textRaw": "`filename` {string} Specifies the filename used in stack traces produced by this script. **Default:** `'evalmachine.'`.",
"name": "filename",
"type": "string",
"default": "`'evalmachine.'`",
"desc": "Specifies the filename used in stack traces produced by this script."
},
{
"textRaw": "`lineOffset` {number} Specifies the line number offset that is displayed in stack traces produced by this script. **Default:** `0`.",
"name": "lineOffset",
"type": "number",
"default": "`0`",
"desc": "Specifies the line number offset that is displayed in stack traces produced by this script."
},
{
"textRaw": "`columnOffset` {number} Specifies the first-line column number offset that is displayed in stack traces produced by this script. **Default:** `0`.",
"name": "columnOffset",
"type": "number",
"default": "`0`",
"desc": "Specifies the first-line column number offset that is displayed in stack traces produced by this script."
},
{
"textRaw": "`displayErrors` {boolean} When `true`, if an [`Error`][] occurs while compiling the `code`, the line of code causing the error is attached to the stack trace. **Default:** `true`.",
"name": "displayErrors",
"type": "boolean",
"default": "`true`",
"desc": "When `true`, if an [`Error`][] occurs while compiling the `code`, the line of code causing the error is attached to the stack trace."
},
{
"textRaw": "`timeout` {integer} Specifies the number of milliseconds to execute `code` before terminating execution. If execution is terminated, an [`Error`][] will be thrown. This value must be a strictly positive integer.",
"name": "timeout",
"type": "integer",
"desc": "Specifies the number of milliseconds to execute `code` before terminating execution. If execution is terminated, an [`Error`][] will be thrown. This value must be a strictly positive integer."
},
{
"textRaw": "`breakOnSigint` {boolean} If `true`, receiving `SIGINT` (Ctrl+C) will terminate execution and throw an [`Error`][]. Existing handlers for the event that have been attached via `process.on('SIGINT')` are disabled during script execution, but continue to work after that. **Default:** `false`.",
"name": "breakOnSigint",
"type": "boolean",
"default": "`false`",
"desc": "If `true`, receiving `SIGINT` (Ctrl+C) will terminate execution and throw an [`Error`][]. Existing handlers for the event that have been attached via `process.on('SIGINT')` are disabled during script execution, but continue to work after that."
},
{
"textRaw": "`contextName` {string} Human-readable name of the newly created context. **Default:** `'VM Context i'`, where `i` is an ascending numerical index of the created context.",
"name": "contextName",
"type": "string",
"default": "`'VM Context i'`, where `i` is an ascending numerical index of the created context",
"desc": "Human-readable name of the newly created context."
},
{
"textRaw": "`contextOrigin` {string} [Origin][origin] 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 [`url.origin`][] property of a [`URL`][] object. Most notably, this string should omit the trailing slash, as that denotes a path. **Default:** `''`.",
"name": "contextOrigin",
"type": "string",
"default": "`''`",
"desc": "[Origin][origin] 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 [`url.origin`][] property of a [`URL`][] object. Most notably, this string should omit the trailing slash, as that denotes a path."
},
{
"textRaw": "`contextCodeGeneration` {Object}",
"name": "contextCodeGeneration",
"type": "Object",
"options": [
{
"textRaw": "`strings` {boolean} If set to false any calls to `eval` or function constructors (`Function`, `GeneratorFunction`, etc) will throw an `EvalError`. **Default:** `true`.",
"name": "strings",
"type": "boolean",
"default": "`true`",
"desc": "If set to false any calls to `eval` or function constructors (`Function`, `GeneratorFunction`, etc) will throw an `EvalError`."
},
{
"textRaw": "`wasm` {boolean} If set to false any attempt to compile a WebAssembly module will throw a `WebAssembly.CompileError`. **Default:** `true`.",
"name": "wasm",
"type": "boolean",
"default": "`true`",
"desc": "If set to false any attempt to compile a WebAssembly module will throw a `WebAssembly.CompileError`."
}
]
},
{
"textRaw": "`cachedData` {Buffer|TypedArray|DataView} Provides an optional `Buffer` or `TypedArray`, or `DataView` with V8's code cache data for the supplied source.",
"name": "cachedData",
"type": "Buffer|TypedArray|DataView",
"desc": "Provides an optional `Buffer` or `TypedArray`, or `DataView` with V8's code cache data for the supplied source."
},
{
"textRaw": "`importModuleDynamically` {Function} Called during evaluation of this module when `import()` is called. If this option is not specified, calls to `import()` will reject with [`ERR_VM_DYNAMIC_IMPORT_CALLBACK_MISSING`][]. This option is part of the experimental modules API. We do not recommend using it in a production environment.",
"name": "importModuleDynamically",
"type": "Function",
"desc": "Called during evaluation of this module when `import()` is called. If this option is not specified, calls to `import()` will reject with [`ERR_VM_DYNAMIC_IMPORT_CALLBACK_MISSING`][]. This option is part of the experimental modules API. We do not recommend using it in a production environment.",
"options": [
{
"textRaw": "`specifier` {string} specifier passed to `import()`",
"name": "specifier",
"type": "string",
"desc": "specifier passed to `import()`"
},
{
"textRaw": "`script` {vm.Script}",
"name": "script",
"type": "vm.Script"
},
{
"textRaw": "`importAssertions` {Object} The `\"assert\"` value passed to the [`optionsExpression`][] optional parameter, or an empty object if no value was provided.",
"name": "importAssertions",
"type": "Object",
"desc": "The `\"assert\"` value passed to the [`optionsExpression`][] optional parameter, or an empty object if no value was provided."
},
{
"textRaw": "Returns: {Module Namespace Object|vm.Module} Returning a `vm.Module` is recommended in order to take advantage of error tracking, and to avoid issues with namespaces that contain `then` function exports.",
"name": "return",
"type": "Module Namespace Object|vm.Module",
"desc": "Returning a `vm.Module` is recommended in order to take advantage of error tracking, and to avoid issues with namespaces that contain `then` function exports."
}
]
},
{
"textRaw": "`microtaskMode` {string} If set to `afterEvaluate`, microtasks (tasks scheduled through `Promise`s and `async function`s) will be run immediately after the script has run. They are included in the `timeout` and `breakOnSigint` scopes in that case.",
"name": "microtaskMode",
"type": "string",
"desc": "If set to `afterEvaluate`, microtasks (tasks scheduled through `Promise`s and `async function`s) will be run immediately after the script has run. They are included in the `timeout` and `breakOnSigint` scopes in that case."
}
]
}
]
}
],
"desc": "The vm.runInNewContext()
first contextifies the given contextObject
(or\ncreates a new contextObject
if passed as undefined
), compiles the code
,\nruns it within the created context, then returns the result. Running code\ndoes not have access to the local scope.
\nIf options
is a string, then it specifies the filename.
\nThe following example compiles and executes code that increments a global\nvariable and sets a new one. These globals are contained in the contextObject
.
\nconst vm = require('node:vm');\n\nconst contextObject = {\n animal: 'cat',\n count: 2\n};\n\nvm.runInNewContext('count += 1; name = \"kitty\"', contextObject);\nconsole.log(contextObject);\n// Prints: { animal: 'cat', count: 3, name: 'kitty' }\n
"
},
{
"textRaw": "`vm.runInThisContext(code[, options])`",
"type": "method",
"name": "runInThisContext",
"meta": {
"added": [
"v0.3.1"
],
"changes": [
{
"version": "v16.12.0",
"pr-url": "https://github.com/nodejs/node/pull/40249",
"description": "Added support for import assertions to the `importModuleDynamically` parameter."
},
{
"version": "v6.3.0",
"pr-url": "https://github.com/nodejs/node/pull/6635",
"description": "The `breakOnSigint` option is supported now."
}
]
},
"signatures": [
{
"return": {
"textRaw": "Returns: {any} the result of the very last statement executed in the script.",
"name": "return",
"type": "any",
"desc": "the result of the very last statement executed in the script."
},
"params": [
{
"textRaw": "`code` {string} The JavaScript code to compile and run.",
"name": "code",
"type": "string",
"desc": "The JavaScript code to compile and run."
},
{
"textRaw": "`options` {Object|string}",
"name": "options",
"type": "Object|string",
"options": [
{
"textRaw": "`filename` {string} Specifies the filename used in stack traces produced by this script. **Default:** `'evalmachine.'`.",
"name": "filename",
"type": "string",
"default": "`'evalmachine.'`",
"desc": "Specifies the filename used in stack traces produced by this script."
},
{
"textRaw": "`lineOffset` {number} Specifies the line number offset that is displayed in stack traces produced by this script. **Default:** `0`.",
"name": "lineOffset",
"type": "number",
"default": "`0`",
"desc": "Specifies the line number offset that is displayed in stack traces produced by this script."
},
{
"textRaw": "`columnOffset` {number} Specifies the first-line column number offset that is displayed in stack traces produced by this script. **Default:** `0`.",
"name": "columnOffset",
"type": "number",
"default": "`0`",
"desc": "Specifies the first-line column number offset that is displayed in stack traces produced by this script."
},
{
"textRaw": "`displayErrors` {boolean} When `true`, if an [`Error`][] occurs while compiling the `code`, the line of code causing the error is attached to the stack trace. **Default:** `true`.",
"name": "displayErrors",
"type": "boolean",
"default": "`true`",
"desc": "When `true`, if an [`Error`][] occurs while compiling the `code`, the line of code causing the error is attached to the stack trace."
},
{
"textRaw": "`timeout` {integer} Specifies the number of milliseconds to execute `code` before terminating execution. If execution is terminated, an [`Error`][] will be thrown. This value must be a strictly positive integer.",
"name": "timeout",
"type": "integer",
"desc": "Specifies the number of milliseconds to execute `code` before terminating execution. If execution is terminated, an [`Error`][] will be thrown. This value must be a strictly positive integer."
},
{
"textRaw": "`breakOnSigint` {boolean} If `true`, receiving `SIGINT` (Ctrl+C) will terminate execution and throw an [`Error`][]. Existing handlers for the event that have been attached via `process.on('SIGINT')` are disabled during script execution, but continue to work after that. **Default:** `false`.",
"name": "breakOnSigint",
"type": "boolean",
"default": "`false`",
"desc": "If `true`, receiving `SIGINT` (Ctrl+C) will terminate execution and throw an [`Error`][]. Existing handlers for the event that have been attached via `process.on('SIGINT')` are disabled during script execution, but continue to work after that."
},
{
"textRaw": "`cachedData` {Buffer|TypedArray|DataView} Provides an optional `Buffer` or `TypedArray`, or `DataView` with V8's code cache data for the supplied source.",
"name": "cachedData",
"type": "Buffer|TypedArray|DataView",
"desc": "Provides an optional `Buffer` or `TypedArray`, or `DataView` with V8's code cache data for the supplied source."
},
{
"textRaw": "`importModuleDynamically` {Function} Called during evaluation of this module when `import()` is called. If this option is not specified, calls to `import()` will reject with [`ERR_VM_DYNAMIC_IMPORT_CALLBACK_MISSING`][]. This option is part of the experimental modules API. We do not recommend using it in a production environment.",
"name": "importModuleDynamically",
"type": "Function",
"desc": "Called during evaluation of this module when `import()` is called. If this option is not specified, calls to `import()` will reject with [`ERR_VM_DYNAMIC_IMPORT_CALLBACK_MISSING`][]. This option is part of the experimental modules API. We do not recommend using it in a production environment.",
"options": [
{
"textRaw": "`specifier` {string} specifier passed to `import()`",
"name": "specifier",
"type": "string",
"desc": "specifier passed to `import()`"
},
{
"textRaw": "`script` {vm.Script}",
"name": "script",
"type": "vm.Script"
},
{
"textRaw": "`importAssertions` {Object} The `\"assert\"` value passed to the [`optionsExpression`][] optional parameter, or an empty object if no value was provided.",
"name": "importAssertions",
"type": "Object",
"desc": "The `\"assert\"` value passed to the [`optionsExpression`][] optional parameter, or an empty object if no value was provided."
},
{
"textRaw": "Returns: {Module Namespace Object|vm.Module} Returning a `vm.Module` is recommended in order to take advantage of error tracking, and to avoid issues with namespaces that contain `then` function exports.",
"name": "return",
"type": "Module Namespace Object|vm.Module",
"desc": "Returning a `vm.Module` is recommended in order to take advantage of error tracking, and to avoid issues with namespaces that contain `then` function exports."
}
]
}
]
}
]
}
],
"desc": "vm.runInThisContext()
compiles code
, runs it within the context of the\ncurrent global
and returns the result. Running code does not have access to\nlocal scope, but does have access to the current global
object.
\nIf options
is a string, then it specifies the filename.
\nThe following example illustrates using both vm.runInThisContext()
and\nthe JavaScript eval()
function to run the same code:
\n\nconst vm = require('node:vm');\nlet localVar = 'initial value';\n\nconst vmResult = vm.runInThisContext('localVar = \"vm\";');\nconsole.log(`vmResult: '${vmResult}', localVar: '${localVar}'`);\n// Prints: vmResult: 'vm', localVar: 'initial value'\n\nconst evalResult = eval('localVar = \"eval\";');\nconsole.log(`evalResult: '${evalResult}', localVar: '${localVar}'`);\n// Prints: evalResult: 'eval', localVar: 'eval'\n
\nBecause vm.runInThisContext()
does not have access to the local scope,\nlocalVar
is unchanged. In contrast, eval()
does have access to the\nlocal scope, so the value localVar
is changed. In this way\nvm.runInThisContext()
is much like an indirect eval()
call, e.g.\n(0,eval)('code')
.
\nExample: Running an HTTP server within a VM
\nWhen using either script.runInThisContext()
or\nvm.runInThisContext()
, the code is executed within the current V8 global\ncontext. The code passed to this VM context will have its own isolated scope.
\nIn order to run a simple web server using the node:http
module the code passed\nto the context must either call require('node:http')
on its own, or have a\nreference to the node:http
module passed to it. For instance:
\n'use strict';\nconst vm = require('node:vm');\n\nconst code = `\n((require) => {\n const http = require('node:http');\n\n http.createServer((request, response) => {\n response.writeHead(200, { 'Content-Type': 'text/plain' });\n response.end('Hello World\\\\n');\n }).listen(8124);\n\n console.log('Server running at http://127.0.0.1:8124/');\n})`;\n\nvm.runInThisContext(code)(require);\n
\nThe require()
in the above case shares the state with the context it is\npassed from. This may introduce risks when untrusted code is executed, e.g.\naltering objects in the context in unwanted ways.
"
}
],
"modules": [
{
"textRaw": "What does it mean to \"contextify\" an object?",
"name": "what_does_it_mean_to_\"contextify\"_an_object?",
"desc": "All JavaScript executed within Node.js runs within the scope of a \"context\".\nAccording to the V8 Embedder's Guide:
\n\nIn V8, a context is an execution environment that allows separate, unrelated,\nJavaScript applications to run in a single instance of V8. You must explicitly\nspecify the context in which you want any JavaScript code to be run.
\n
\nWhen the method vm.createContext()
is called, the contextObject
argument\n(or a newly-created object if contextObject
is undefined
) is associated\ninternally with a new instance of a V8 Context. This V8 Context provides the\ncode
run using the node:vm
module's methods with an isolated global\nenvironment within which it can operate. The process of creating the V8 Context\nand associating it with the contextObject
is what this document refers to as\n\"contextifying\" the object.
",
"type": "module",
"displayName": "What does it mean to \"contextify\" an object?"
},
{
"textRaw": "Timeout interactions with asynchronous tasks and Promises",
"name": "timeout_interactions_with_asynchronous_tasks_and_promises",
"desc": "Promise
s and async function
s can schedule tasks run by the JavaScript\nengine asynchronously. By default, these tasks are run after all JavaScript\nfunctions on the current stack are done executing.\nThis allows escaping the functionality of the timeout
and\nbreakOnSigint
options.
\nFor example, the following code executed by vm.runInNewContext()
with a\ntimeout of 5 milliseconds schedules an infinite loop to run after a promise\nresolves. The scheduled loop is never interrupted by the timeout:
\nconst vm = require('node:vm');\n\nfunction loop() {\n console.log('entering loop');\n while (1) console.log(Date.now());\n}\n\nvm.runInNewContext(\n 'Promise.resolve().then(() => loop());',\n { loop, console },\n { timeout: 5 }\n);\n// This is printed *before* 'entering loop' (!)\nconsole.log('done executing');\n
\nThis can be addressed by passing microtaskMode: 'afterEvaluate'
to the code\nthat creates the Context
:
\nconst vm = require('node:vm');\n\nfunction loop() {\n while (1) console.log(Date.now());\n}\n\nvm.runInNewContext(\n 'Promise.resolve().then(() => loop());',\n { loop, console },\n { timeout: 5, microtaskMode: 'afterEvaluate' }\n);\n
\nIn this case, the microtask scheduled through promise.then()
will be run\nbefore returning from vm.runInNewContext()
, and will be interrupted\nby the timeout
functionality. This applies only to code running in a\nvm.Context
, so e.g. vm.runInThisContext()
does not take this option.
\nPromise callbacks are entered into the microtask queue of the context in which\nthey were created. For example, if () => loop()
is replaced with just loop
\nin the above example, then loop
will be pushed into the global microtask\nqueue, because it is a function from the outer (main) context, and thus will\nalso be able to escape the timeout.
\nIf asynchronous scheduling functions such as process.nextTick()
,\nqueueMicrotask()
, setTimeout()
, setImmediate()
, etc. are made available\ninside a vm.Context
, functions passed to them will be added to global queues,\nwhich are shared by all contexts. Therefore, callbacks passed to those functions\nare not controllable through the timeout either.
",
"type": "module",
"displayName": "Timeout interactions with asynchronous tasks and Promises"
}
],
"type": "module",
"displayName": "vm"
}
]
}