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method Script.prototype.runInNewContext

#Script.prototype.runInNewContext(): any

This method is a shortcut to script.runInContext(vm.createContext(options), options). It does several things at once:

  1. Creates a new context.
  2. If contextObject is an object, contextifies it with the new context. If contextObject is undefined, creates a new object and contextifies it. If contextObject is vm.constants.DONT_CONTEXTIFY, don't contextify anything.
  3. Runs the compiled code contained by the vm.Script object within the created context. The code does not have access to the scope in which this method is called.
  4. Returns the result.

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 context.

const vm = require('node:vm');

const script = new vm.Script('globalVar = "set"');

const contexts = [{}, {}, {}];
contexts.forEach((context) => {
  script.runInNewContext(context);
});

console.log(contexts);
// Prints: [{ globalVar: 'set' }, { globalVar: 'set' }, { globalVar: 'set' }]

// This would throw if the context is created from a contextified object.
// vm.constants.DONT_CONTEXTIFY allows creating contexts with ordinary
// global objects that can be frozen.
const freezeScript = new vm.Script('Object.freeze(globalThis); globalThis;');
const frozenContext = freezeScript.runInNewContext(vm.constants.DONT_CONTEXTIFY);

Parameters #

#contextObject: Context | constants.DONT_CONTEXTIFY
optional

Either vm.constants.DONT_CONTEXTIFY or an object that will be contextified. If undefined, an empty contextified object will be created for backwards compatibility.

Return Type #

any

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