Global objects | Node.js v24.0.0 Documentation (original) (raw)

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 objectsthat are part of the JavaScript language itself, which are also globally accessible.

Class: AbortController#

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])#

• reason An optional reason, retrievable on the AbortSignal'sreason 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:

Class: AbortSignal#

Added in: v15.0.0, v14.17.0

• Extends:

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

Static method: AbortSignal.abort([reason])#

• reason:
• Returns:

Returns a new already aborted AbortSignal.

Static method: AbortSignal.timeout(delay)#

Added in: v17.3.0, v16.14.0

• delay 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: True after the AbortController has been aborted.

abortSignal.onabort#

Added in: v15.0.0, v14.17.0

• Type:

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:

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 .

Class: Buffer#

Added in: v0.1.103

Used to handle binary data. See the buffer section.

Class: ByteLengthQueuingStrategy#

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

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

Global alias for buffer.atob().

BroadcastChannel#

Added in: v18.0.0

See .

btoa(data)#

Added in: v16.0.0

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#

A browser-compatible implementation of CompressionStream.

console#

Added in: v0.1.100

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

Class: CountQueuingStrategy#

A browser-compatible implementation of CountQueuingStrategy.

Crypto#

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

crypto#

A browser-compatible implementation of the Web Crypto API.

CryptoKey#

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

CustomEvent#

A browser-compatible implementation of the CustomEvent Web API.

Class: DecompressionStream#

A browser-compatible implementation of DecompressionStream.

Event#

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

EventSource#

Added in: v22.3.0, v20.18.0

A browser-compatible implementation of the EventSource class.

EventTarget#

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

exports#

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

fetch#

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

const res = await fetch('https://nodejs.org/api/documentation.json'); if (res.ok) { const data = await res.json(); console.log(data); }

The implementation is based upon undici, an HTTP/1.1 client written from scratch for Node.js. You can figure out which version of undici is bundled in your Node.js process reading the process.versions.undici property.

Custom dispatcher#

You can use a custom dispatcher to dispatch requests passing it in fetch's options object. The dispatcher must be compatible with undici'sDispatcher class.

fetch(url, { dispatcher: new MyAgent() });

It is possible to change the global dispatcher in Node.js installing undici and using the setGlobalDispatcher() method. Calling this method will affect both undici and Node.js.

import { setGlobalDispatcher } from 'undici'; setGlobalDispatcher(new MyAgent());

Related classes#

The following globals are available to use with fetch:

• FormData
• Headers
• Request
• Response.

Class: File#

Added in: v20.0.0

See .

Class FormData#

A browser-compatible implementation of .

global#

Added in: v0.1.27

• 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 anECMAScript module.

Class Headers#

A browser-compatible implementation of .

localStorage#

Added in: v22.4.0

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

A partial implementation of the Navigator API.

navigator#

Added in: v21.0.0

A partial implementation of window.navigator.

navigator.hardwareConcurrency#

Added in: v21.0.0

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

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 ofnavigator.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

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

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. SeePerformanceObserverEntryList 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

The process object. See the process object section.

queueMicrotask(callback)#

Added in: v11.0.0

• callback Function to be queued.

The queueMicrotask() method queues a microtask to invoke callback. Ifcallback 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. Theprocess.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#

A browser-compatible implementation of ReadableByteStreamController.

Class: ReadableStream#

A browser-compatible implementation of ReadableStream.

Class: ReadableStreamBYOBReader#

A browser-compatible implementation of ReadableStreamBYOBReader.

Class: ReadableStreamBYOBRequest#

A browser-compatible implementation of ReadableStreamBYOBRequest.

Class: ReadableStreamDefaultController#

A browser-compatible implementation of ReadableStreamDefaultController.

Class: ReadableStreamDefaultReader#

A browser-compatible implementation of ReadableStreamDefaultReader.

require()#

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

Response#

A browser-compatible implementation of .

Request#

A browser-compatible implementation of .

sessionStorage#

Added in: v22.4.0

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

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#

A browser-compatible implementation of . This global is available only if the Node.js binary was compiled with including support for thenode: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#

A browser-compatible implementation of TextDecoderStream.

TextEncoder#

Added in: v11.0.0

The WHATWG TextEncoder class. See the TextEncoder section.

Class: TextEncoderStream#

A browser-compatible implementation of TextEncoderStream.

Class: TransformStream#

A browser-compatible implementation of TransformStream.

Class: TransformStreamDefaultController#

A browser-compatible implementation of TransformStreamDefaultController.

URL#

Added in: v10.0.0

The WHATWG URL class. See the URL section.

URLPattern#

Added in: v24.0.0

The WHATWG URLPattern class. See the URLPattern section.

URLSearchParams#

Added in: v10.0.0

The WHATWG URLSearchParams class. See the URLSearchParams section.

WebAssembly#

Added in: v8.0.0

The object that acts as the namespace for all W3CWebAssembly related functionality. See theMozilla Developer Network for usage and compatibility.

WebSocket#

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

Class: WritableStream#

A browser-compatible implementation of WritableStream.

Class: WritableStreamDefaultController#

A browser-compatible implementation of WritableStreamDefaultController.

Class: WritableStreamDefaultWriter#

A browser-compatible implementation of WritableStreamDefaultWriter.