vm.runInThisContext

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vm.runInThisContext(code, options?): any

Attributes

code:string

The JavaScript code to compile and run.

options:Object | string

filename?:string

Specifies the filename used in stack traces produced by this script. Default: 'evalmachine.<anonymous>'.

lineOffset?:number

Specifies the line number offset that is displayed in stack traces produced by this script. Default: 0.

columnOffset?:number

Specifies the first-line column number offset that is displayed in stack traces produced by this script. Default: 0.

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.

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.

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.

cachedData:Buffer | TypedArray | DataView

Provides an optional Buffer or TypedArray, or DataView with V8's code cache data for the supplied source.

importModuleDynamically:Function | vm.constants.USE_MAIN_CONTEXT_DEFAULT_LOADER

Used to specify the how the modules should be loaded during the evaluation of this script when import() is called. This option is part of the experimental modules API. We do not recommend using it in a production environment. For detailed information, see Support of dynamic import() in compilation APIs.

Returns:any

the result of the very last statement executed in the script.

vm.runInThisContext() compiles code, runs it within the context of the current global and returns the result. Running code does not have access to local scope, but does have access to the current global object.

If options is a string, then it specifies the filename.

The following example illustrates using both vm.runInThisContext() and the JavaScript eval() function to run the same code:

import { runInThisContext } from 'node:vm';
let localVar = 'initial value';

const vmResult = runInThisContext('localVar = "vm";');
console.log(`vmResult: '${vmResult}', localVar: '${localVar}'`);
// Prints: vmResult: 'vm', localVar: 'initial value'

const evalResult = eval('localVar = "eval";');
console.log(`evalResult: '${evalResult}', localVar: '${localVar}'`);
// Prints: evalResult: 'eval', localVar: 'eval'

JavaScript

const { runInThisContext } = require('node:vm');
let localVar = 'initial value';

const vmResult = runInThisContext('localVar = "vm";');
console.log(`vmResult: '${vmResult}', localVar: '${localVar}'`);
// Prints: vmResult: 'vm', localVar: 'initial value'

const evalResult = eval('localVar = "eval";');
console.log(`evalResult: '${evalResult}', localVar: '${localVar}'`);
// Prints: evalResult: 'eval', localVar: 'eval'

JavaScript

Because vm.runInThisContext() does not have access to the local scope, localVar is unchanged. In contrast, a direct eval() call does have access to the local scope, so the value localVar is changed. In this way vm.runInThisContext() is much like an indirect eval() call, e.g. (0,eval)('code').