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:
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#
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);
abortController.abort([reason])#
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
Class: AbortSignal#
Added in: v15.0.0, v14.17.0
The AbortSignal is used to notify observers when the
abortController.abort() method is called.
Static method: AbortSignal.abort([reason])#
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();
ac.signal.onabort = () => console.log('aborted!');
ac.signal.addEventListener('abort', (event) => {
console.log(event.type);
}, { 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
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
An optional reason specified when the AbortSignal was triggered.
const ac = new AbortController();
ac.abort(new Error('boom!'));
console.log(ac.signal.reason);
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
Used to handle binary data. See the buffer section.
__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.
console#
Added in: v0.1.100
Used to print to stdout and stderr. See the console section.
Class: Crypto#
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.
Class: CryptoKey#
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.
Class: CustomEvent#
A browser-compatible implementation of <CustomEvent>.
Class: EventSource#
Added in: v22.3.0
A browser-compatible implementation of <EventSource>.
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's
Dispatcher class.
fetch(url, { dispatcher: new MyAgent() });
It is possible to change the global dispatcher in Node.js by 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:
Class: File#
Added in: v20.0.0
See <File>.
Class: FormData#
A browser-compatible implementation of <FormData>.
global#
Added in: v0.1.27
- Type: <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
A browser-compatible implementation of <Headers>.
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.
Class: MessageChannel#
Added in: v15.0.0
The MessageChannel class. See MessageChannel for more details.
Class: MessageEvent#
Added in: v15.0.0
A browser-compatible implementation of <MessageEvent>.
Class: 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.
Class: 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
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
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}`);
Class: PerformanceEntry#
Added in: v19.0.0
The PerformanceEntry class. See PerformanceEntry for more details.
Class: PerformanceMark#
Added in: v19.0.0
The PerformanceMark class. See PerformanceMark for more details.
Class: PerformanceMeasure#
Added in: v19.0.0
The PerformanceMeasure class. See PerformanceMeasure for more details.
Class: PerformanceObserver#
Added in: v19.0.0
The PerformanceObserver class. See PerformanceObserver for more details.
Class: PerformanceObserverEntryList#
Added in: v19.0.0
The PerformanceObserverEntryList class. See
PerformanceObserverEntryList for more details.
Class: PerformanceResourceTiming#
Added in: v19.0.0
The PerformanceResourceTiming class. See PerformanceResourceTiming for
more details.
process#
Added in: v0.1.7
The process object. See the process object section.
queueMicrotask(callback)#
Added in: v11.0.0
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.
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: ReadableStream#
A browser-compatible implementation of ReadableStream.
require()#
This variable may appear to be global but is not. See require().
Class: Response#
A browser-compatible implementation of <Response>.
Class: Request#
A browser-compatible implementation of <Request>.
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>.
structuredClone(value[, options])#
Added in: v17.0.0
The WHATWG structuredClone method.
Class: SubtleCrypto#
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.
Class: TextDecoder#
Added in: v11.0.0
The WHATWG TextDecoder class. See the TextDecoder section.
Class: TextEncoder#
Added in: v11.0.0
The WHATWG TextEncoder class. See the TextEncoder section.
Class: URL#
Added in: v10.0.0
The WHATWG URL class. See the URL section.
Class: URLSearchParams#
Added in: v10.0.0
The WHATWG URLSearchParams class. See the URLSearchParams section.
Class: WritableStream#
A browser-compatible implementation of WritableStream.