Global objects

These objects are available in all modules.

The following variables may appear to be global but are not. They exist only in the scope of CommonJS modules:

• __dirname
• __filename
• exports
• module
• require()

The objects listed here are specific to Node.js. There are built-in objects that are part of the JavaScript language itself, which are also globally accessible.

Class: AbortController

[History]

Version	Changes
v15.4.0	No longer experimental.
v15.0.0, v14.17.0	Added in: v15.0.0, v14.17.0

A utility class used to signal cancelation in selected Promise-based APIs. The API is based on the Web API AbortController.

const ac = new AbortController();

ac.signal.addEventListener('abort', () => console.log('Aborted!'),
                           { once: true });

ac.abort();

console.log(ac.signal.aborted);  // Prints true

abortController.abort([reason])

[History]

Version	Changes
v17.2.0, v16.14.0	Added the new optional reason argument.
v15.0.0, v14.17.0	Added in: v15.0.0, v14.17.0

• reason <any> An optional reason, retrievable on the AbortSignal's reason property.

Triggers the abort signal, causing the abortController.signal to emit the 'abort' event.

abortController.signal

Added in: v15.0.0, v14.17.0

• Type: <AbortSignal>

Class: AbortSignal

Added in: v15.0.0, v14.17.0

• Extends: <EventTarget>

The AbortSignal is used to notify observers when the abortController.abort() method is called.

Static method: AbortSignal.abort([reason])

[History]

Version	Changes
v17.2.0, v16.14.0	Added the new optional reason argument.
v15.12.0, v14.17.0	Added in: v15.12.0, v14.17.0

• reason: <any>
• Returns: <AbortSignal>

Returns a new already aborted AbortSignal.

Static method: AbortSignal.timeout(delay)

Added in: v17.3.0, v16.14.0

• delay <number> The number of milliseconds to wait before triggering the AbortSignal.

Returns a new AbortSignal which will be aborted in delay milliseconds.

Static method: AbortSignal.any(signals)

Added in: v20.3.0, v18.17.0

• signals <AbortSignal[]> The AbortSignals of which to compose a new AbortSignal.

Returns a new AbortSignal which will be aborted if any of the provided signals are aborted. Its abortSignal.reason will be set to whichever one of the signals caused it to be aborted.

Event: 'abort'

Added in: v15.0.0, v14.17.0

The 'abort' event is emitted when the abortController.abort() method is called. The callback is invoked with a single object argument with a single type property set to 'abort':

const ac = new AbortController();

// Use either the onabort property...
ac.signal.onabort = () => console.log('aborted!');

// Or the EventTarget API...
ac.signal.addEventListener('abort', (event) => {
  console.log(event.type);  // Prints 'abort'
}, { once: true });

ac.abort();

The AbortController with which the AbortSignal is associated will only ever trigger the 'abort' event once. We recommended that code check that the abortSignal.aborted attribute is false before adding an 'abort' event listener.

Any event listeners attached to the AbortSignal should use the { once: true } option (or, if using the EventEmitter APIs to attach a listener, use the once() method) to ensure that the event listener is removed as soon as the 'abort' event is handled. Failure to do so may result in memory leaks.

abortSignal.aborted

Added in: v15.0.0, v14.17.0

• Type: <boolean> True after the AbortController has been aborted.

abortSignal.onabort

Added in: v15.0.0, v14.17.0

• Type: <Function>

An optional callback function that may be set by user code to be notified when the abortController.abort() function has been called.

abortSignal.reason

Added in: v17.2.0, v16.14.0

• Type: <any>

An optional reason specified when the AbortSignal was triggered.

const ac = new AbortController();
ac.abort(new Error('boom!'));
console.log(ac.signal.reason);  // Error: boom!

abortSignal.throwIfAborted()

Added in: v17.3.0, v16.17.0

If abortSignal.aborted is true, throws abortSignal.reason.

Class: Blob

Added in: v18.0.0

See <Blob>.

Class: Buffer

Added in: v0.1.103

• <Function>

Used to handle binary data. See the buffer section.

Class: ByteLengthQueuingStrategy

Added in: v18.0.0

[Stable: 1 - Experimental]

Stable: 1 Stability: 1 - Experimental.

A browser-compatible implementation of ByteLengthQueuingStrategy.

__dirname

This variable may appear to be global but is not. See __dirname.

__filename

This variable may appear to be global but is not. See __filename.

atob(data)

Added in: v16.0.0

[Stable: 3 - Legacy]

Stable: 3 Stability: 3 - Legacy. Use Buffer.from(data, 'base64') instead.

Global alias for buffer.atob().

BroadcastChannel

Added in: v18.0.0

See <BroadcastChannel>.

btoa(data)

Added in: v16.0.0

[Stable: 3 - Legacy]

Stable: 3 Stability: 3 - Legacy. Use buf.toString('base64') instead.

Global alias for buffer.btoa().

clearImmediate(immediateObject)

Added in: v0.9.1

clearImmediate is described in the timers section.

clearInterval(intervalObject)

Added in: v0.0.1

clearInterval is described in the timers section.

clearTimeout(timeoutObject)

Added in: v0.0.1

clearTimeout is described in the timers section.

CloseEvent

Added in: v23.0.0

The CloseEvent class. See CloseEvent for more details.

A browser-compatible implementation of CloseEvent. Disable this API with the --no-experimental-websocket CLI flag.

Class: CompressionStream

Added in: v18.0.0

[Stable: 1 - Experimental]

Stable: 1 Stability: 1 - Experimental.

A browser-compatible implementation of CompressionStream.

console

Added in: v0.1.100

• <Object>

Used to print to stdout and stderr. See the console section.

Class: CountQueuingStrategy

Added in: v18.0.0

[Stable: 1 - Experimental]

Stable: 1 Stability: 1 - Experimental.

A browser-compatible implementation of CountQueuingStrategy.

Crypto

[History]

Version	Changes
v23.0.0	No longer experimental.
v19.0.0	No longer behind --experimental-global-webcrypto CLI flag.
v17.6.0, v16.15.0	Added in: v17.6.0, v16.15.0

[Stable: 2 - Stable]

Stable: 2 Stability: 2 - Stable.

A browser-compatible implementation of <Crypto>. This global is available only if the Node.js binary was compiled with including support for the node:crypto module.

crypto

[History]

Version	Changes
v23.0.0	No longer experimental.
v19.0.0	No longer behind --experimental-global-webcrypto CLI flag.
v17.6.0, v16.15.0	Added in: v17.6.0, v16.15.0

[Stable: 2 - Stable]

Stable: 2 Stability: 2 - Stable.

A browser-compatible implementation of the Web Crypto API.

CryptoKey

[History]

Version	Changes
v23.0.0	No longer experimental.
v19.0.0	No longer behind --experimental-global-webcrypto CLI flag.
v17.6.0, v16.15.0	Added in: v17.6.0, v16.15.0

[Stable: 2 - Stable]

Stable: 2 Stability: 2 - Stable.

A browser-compatible implementation of <CryptoKey>. This global is available only if the Node.js binary was compiled with including support for the node:crypto module.

CustomEvent

[History]

Version	Changes
v23.0.0	No longer experimental.
v22.1.0, v20.13.0	CustomEvent is now stable.
v19.0.0	No longer behind --experimental-global-customevent CLI flag.
v18.7.0, v16.17.0	Added in: v18.7.0, v16.17.0

[Stable: 2 - Stable]

Stable: 2 Stability: 2 - Stable

A browser-compatible implementation of the CustomEvent Web API.

Class: DecompressionStream

Added in: v18.0.0

[Stable: 1 - Experimental]

Stable: 1 Stability: 1 - Experimental.

A browser-compatible implementation of DecompressionStream.

Event

[History]

Version	Changes
v15.4.0	No longer experimental.
v15.0.0	Added in: v15.0.0

A browser-compatible implementation of the Event class. See EventTarget and Event API for more details.

EventSource

Added in: v22.3.0, v20.18.0

[Stable: 1 - Experimental]

Stable: 1 Stability: 1 - Experimental. Enable this API with the --experimental-eventsource CLI flag.

A browser-compatible implementation of the EventSource class.

EventTarget

[History]

Version	Changes
v15.4.0	No longer experimental.
v15.0.0	Added in: v15.0.0

A browser-compatible implementation of the EventTarget class. See EventTarget and Event API for more details.

exports

This variable may appear to be global but is not. See exports.

fetch

[History]

Version	Changes
v21.0.0	No longer experimental.
v18.0.0	No longer behind --experimental-fetch CLI flag.
v17.5.0, v16.15.0	Added in: v17.5.0, v16.15.0

[Stable: 2 - Stable]

Stable: 2 Stability: 2 - Stable

A browser-compatible implementation of the fetch() function.

Class: File

Added in: v20.0.0

See <File>.

Class FormData

[History]

Version	Changes
v21.0.0	No longer experimental.
v18.0.0	No longer behind --experimental-fetch CLI flag.
v17.6.0, v16.15.0	Added in: v17.6.0, v16.15.0

[Stable: 2 - Stable]

Stable: 2 Stability: 2 - Stable

A browser-compatible implementation of <FormData>.

global

Added in: v0.1.27

[Stable: 3 - Legacy]

Stable: 3 Stability: 3 - Legacy. Use globalThis instead.

• <Object> The global namespace object.

In browsers, the top-level scope has traditionally been the global scope. This means that var something will define a new global variable, except within ECMAScript modules. In Node.js, this is different. The top-level scope is not the global scope; var something inside a Node.js module will be local to that module, regardless of whether it is a CommonJS module or an ECMAScript module.

Class Headers

[History]

Version	Changes
v21.0.0	No longer experimental.
v18.0.0	No longer behind --experimental-fetch CLI flag.
v17.5.0, v16.15.0	Added in: v17.5.0, v16.15.0

[Stable: 2 - Stable]

Stable: 2 Stability: 2 - Stable

A browser-compatible implementation of <Headers>.

localStorage

Added in: v22.4.0

[Stable: 1 - Experimental]

Stable: 1 Stability: 1.0 - Early development.

A browser-compatible implementation of localStorage. Data is stored unencrypted in the file specified by the --localstorage-file CLI flag. The maximum amount of data that can be stored is 10 MB. Any modification of this data outside of the Web Storage API is not supported. Enable this API with the --experimental-webstorage CLI flag. localStorage data is not stored per user or per request when used in the context of a server, it is shared across all users and requests.

MessageChannel

Added in: v15.0.0

The MessageChannel class. See MessageChannel for more details.

MessageEvent

Added in: v15.0.0

The MessageEvent class. See MessageEvent for more details.

MessagePort

Added in: v15.0.0

The MessagePort class. See MessagePort for more details.

module

This variable may appear to be global but is not. See module.

Navigator

Added in: v21.0.0

[Stable: 1 - Experimental]

Stable: 1 Stability: 1.1 - Active development. Disable this API with the --no-experimental-global-navigator CLI flag.

A partial implementation of the Navigator API.

navigator

Added in: v21.0.0

[Stable: 1 - Experimental]

Stable: 1 Stability: 1.1 - Active development. Disable this API with the --no-experimental-global-navigator CLI flag.

A partial implementation of window.navigator.

navigator.hardwareConcurrency

Added in: v21.0.0

• <number>

The navigator.hardwareConcurrency read-only property returns the number of logical processors available to the current Node.js instance.

console.log(`This process is running on ${navigator.hardwareConcurrency} logical processors`);

navigator.language

Added in: v21.2.0

• <string>

The navigator.language read-only property returns a string representing the preferred language of the Node.js instance. The language will be determined by the ICU library used by Node.js at runtime based on the default language of the operating system.

The value is representing the language version as defined in RFC 5646.

The fallback value on builds without ICU is 'en-US'.

console.log(`The preferred language of the Node.js instance has the tag '${navigator.language}'`);

navigator.languages

Added in: v21.2.0

• {Array

The navigator.languages read-only property returns an array of strings representing the preferred languages of the Node.js instance. By default navigator.languages contains only the value of navigator.language, which will be determined by the ICU library used by Node.js at runtime based on the default language of the operating system.

The fallback value on builds without ICU is ['en-US'].

console.log(`The preferred languages are '${navigator.languages}'`);

navigator.platform

Added in: v21.2.0

• <string>

The navigator.platform read-only property returns a string identifying the platform on which the Node.js instance is running.

console.log(`This process is running on ${navigator.platform}`);

navigator.userAgent

Added in: v21.1.0

• <string>

The navigator.userAgent read-only property returns user agent consisting of the runtime name and major version number.

console.log(`The user-agent is ${navigator.userAgent}`); // Prints "Node.js/21"

PerformanceEntry

Added in: v19.0.0

The PerformanceEntry class. See PerformanceEntry for more details.

PerformanceMark

Added in: v19.0.0

The PerformanceMark class. See PerformanceMark for more details.

PerformanceMeasure

Added in: v19.0.0

The PerformanceMeasure class. See PerformanceMeasure for more details.

PerformanceObserver

Added in: v19.0.0

The PerformanceObserver class. See PerformanceObserver for more details.

PerformanceObserverEntryList

Added in: v19.0.0

The PerformanceObserverEntryList class. See PerformanceObserverEntryList for more details.

PerformanceResourceTiming

Added in: v19.0.0

The PerformanceResourceTiming class. See PerformanceResourceTiming for more details.

performance

Added in: v16.0.0

The perf_hooks.performance object.

process

Added in: v0.1.7

• <Object>

The process object. See the process object section.

queueMicrotask(callback)

Added in: v11.0.0

• callback <Function> Function to be queued.

The queueMicrotask() method queues a microtask to invoke callback. If callback throws an exception, the process object 'uncaughtException' event will be emitted.

The microtask queue is managed by V8 and may be used in a similar manner to the process.nextTick() queue, which is managed by Node.js. The process.nextTick() queue is always processed before the microtask queue within each turn of the Node.js event loop.

// Here, `queueMicrotask()` is used to ensure the 'load' event is always
// emitted asynchronously, and therefore consistently. Using
// `process.nextTick()` here would result in the 'load' event always emitting
// before any other promise jobs.

DataHandler.prototype.load = async function load(key) {
  const hit = this._cache.get(key);
  if (hit !== undefined) {
    queueMicrotask(() => {
      this.emit('load', hit);
    });
    return;
  }

  const data = await fetchData(key);
  this._cache.set(key, data);
  this.emit('load', data);
};

Class: ReadableByteStreamController

Added in: v18.0.0

[Stable: 1 - Experimental]

Stable: 1 Stability: 1 - Experimental.

A browser-compatible implementation of ReadableByteStreamController.

Class: ReadableStream

Added in: v18.0.0

[Stable: 1 - Experimental]

Stable: 1 Stability: 1 - Experimental.

A browser-compatible implementation of ReadableStream.

Class: ReadableStreamBYOBReader

Added in: v18.0.0

[Stable: 1 - Experimental]

Stable: 1 Stability: 1 - Experimental.

A browser-compatible implementation of ReadableStreamBYOBReader.

Class: ReadableStreamBYOBRequest

Added in: v18.0.0

[Stable: 1 - Experimental]

Stable: 1 Stability: 1 - Experimental.

A browser-compatible implementation of ReadableStreamBYOBRequest.

Class: ReadableStreamDefaultController

Added in: v18.0.0

[Stable: 1 - Experimental]

Stable: 1 Stability: 1 - Experimental.

A browser-compatible implementation of ReadableStreamDefaultController.

Class: ReadableStreamDefaultReader

Added in: v18.0.0

[Stable: 1 - Experimental]

Stable: 1 Stability: 1 - Experimental.

A browser-compatible implementation of ReadableStreamDefaultReader.

require()

This variable may appear to be global but is not. See require().

Response

[History]

Version	Changes
v21.0.0	No longer experimental.
v18.0.0	No longer behind --experimental-fetch CLI flag.
v17.5.0, v16.15.0	Added in: v17.5.0, v16.15.0

[Stable: 2 - Stable]

Stable: 2 Stability: 2 - Stable

A browser-compatible implementation of <Response>.

Request

[History]

Version	Changes
v21.0.0	No longer experimental.
v18.0.0	No longer behind --experimental-fetch CLI flag.
v17.5.0, v16.15.0	Added in: v17.5.0, v16.15.0

[Stable: 2 - Stable]

Stable: 2 Stability: 2 - Stable

A browser-compatible implementation of <Request>.

sessionStorage

Added in: v22.4.0

[Stable: 1 - Experimental]

Stable: 1 Stability: 1.0 - Early development.

A browser-compatible implementation of sessionStorage. Data is stored in memory, with a storage quota of 10 MB. sessionStorage data persists only within the currently running process, and is not shared between workers.

setImmediate(callback[, ...args])

Added in: v0.9.1

setImmediate is described in the timers section.

setInterval(callback, delay[, ...args])

Added in: v0.0.1

setInterval is described in the timers section.

setTimeout(callback, delay[, ...args])

Added in: v0.0.1

setTimeout is described in the timers section.

Class: Storage

Added in: v22.4.0

[Stable: 1 - Experimental]

Stable: 1 Stability: 1.0 - Early development.

A browser-compatible implementation of Storage. Enable this API with the --experimental-webstorage CLI flag.

structuredClone(value[, options])

Added in: v17.0.0

The WHATWG structuredClone method.

SubtleCrypto

[History]

Version	Changes
v19.0.0	No longer behind --experimental-global-webcrypto CLI flag.
v17.6.0, v16.15.0	Added in: v17.6.0, v16.15.0

[Stable: 2 - Stable]

Stable: 2 Stability: 2 - Stable.

A browser-compatible implementation of <SubtleCrypto>. This global is available only if the Node.js binary was compiled with including support for the node:crypto module.

DOMException

Added in: v17.0.0

The WHATWG DOMException class. See DOMException for more details.

TextDecoder

Added in: v11.0.0

The WHATWG TextDecoder class. See the TextDecoder section.

Class: TextDecoderStream

Added in: v18.0.0

[Stable: 1 - Experimental]

Stable: 1 Stability: 1 - Experimental.

A browser-compatible implementation of TextDecoderStream.

TextEncoder

Added in: v11.0.0

The WHATWG TextEncoder class. See the TextEncoder section.

Class: TextEncoderStream

Added in: v18.0.0

[Stable: 1 - Experimental]

Stable: 1 Stability: 1 - Experimental.

A browser-compatible implementation of TextEncoderStream.

Class: TransformStream

Added in: v18.0.0

[Stable: 1 - Experimental]

Stable: 1 Stability: 1 - Experimental.

A browser-compatible implementation of TransformStream.

Class: TransformStreamDefaultController

Added in: v18.0.0

[Stable: 1 - Experimental]

Stable: 1 Stability: 1 - Experimental.

A browser-compatible implementation of TransformStreamDefaultController.

URL

Added in: v10.0.0

The WHATWG URL class. See the URL section.

URLSearchParams

Added in: v10.0.0

The WHATWG URLSearchParams class. See the URLSearchParams section.

WebAssembly

Added in: v8.0.0

• <Object>

The object that acts as the namespace for all W3C WebAssembly related functionality. See the Mozilla Developer Network for usage and compatibility.

WebSocket

[History]

Version	Changes
v22.4.0	No longer experimental.
v22.0.0	No longer behind --experimental-websocket CLI flag.
v21.0.0, v20.10.0	Added in: v21.0.0, v20.10.0

[Stable: 2 - Stable]

Stable: 2 Stability: 2 - Stable.

A browser-compatible implementation of WebSocket. Disable this API with the --no-experimental-websocket CLI flag.

Class: WritableStream

Added in: v18.0.0

[Stable: 1 - Experimental]

Stable: 1 Stability: 1 - Experimental.

A browser-compatible implementation of WritableStream.

Class: WritableStreamDefaultController

Added in: v18.0.0

[Stable: 1 - Experimental]

Stable: 1 Stability: 1 - Experimental.

A browser-compatible implementation of WritableStreamDefaultController.

Class: WritableStreamDefaultWriter

Added in: v18.0.0

[Stable: 1 - Experimental]

Stable: 1 Stability: 1 - Experimental.

A browser-compatible implementation of WritableStreamDefaultWriter.