Global objects | Node.js v18.20.4 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 modules, see themodule system documentation:

• __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: 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

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#

Added in: v18.0.0

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.

Class: CompressionStream#

Added in: v18.0.0

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#

Added in: v18.0.0

A browser-compatible implementation of CountQueuingStrategy.

Crypto#

Added in: v17.6.0

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#

Added in: v17.6.0

A browser-compatible implementation of the Web Crypto API.

CryptoKey#

Added in: v17.6.0

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#

Added in: v18.7.0

A browser-compatible implementation of the CustomEvent Web API.

Class: DecompressionStream#

Added in: v18.0.0

A browser-compatible implementation of DecompressionStream.

Event#

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

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.

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 .

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.

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#

Added in: v18.0.0

A browser-compatible implementation of ReadableByteStreamController.

Class: ReadableStream#

Added in: v18.0.0

A browser-compatible implementation of ReadableStream.

Class: ReadableStreamBYOBReader#

Added in: v18.0.0

A browser-compatible implementation of ReadableStreamBYOBReader.

Class: ReadableStreamBYOBRequest#

Added in: v18.0.0

A browser-compatible implementation of ReadableStreamBYOBRequest.

Class: ReadableStreamDefaultController#

Added in: v18.0.0

A browser-compatible implementation of ReadableStreamDefaultController.

Class: ReadableStreamDefaultReader#

Added in: v18.0.0

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 .

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.

structuredClone(value[, options])#

Added in: v17.0.0

The WHATWG structuredClone method.

SubtleCrypto#

Added in: v17.6.0

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#

Added in: v18.0.0

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

A browser-compatible implementation of TextEncoderStream.

Class: TransformStream#

Added in: v18.0.0

A browser-compatible implementation of TransformStream.

Class: TransformStreamDefaultController#

Added in: v18.0.0

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

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

Class: WritableStream#

Added in: v18.0.0

A browser-compatible implementation of WritableStream.

Class: WritableStreamDefaultController#

Added in: v18.0.0

A browser-compatible implementation of WritableStreamDefaultController.

Class: WritableStreamDefaultWriter#

Added in: v18.0.0

A browser-compatible implementation of WritableStreamDefaultWriter.