# Global objects

<!--introduced_in=v0.10.0-->

<!-- type=misc -->

> Stability: 2 - Stable

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`

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

```js
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])`

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* `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`

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* Type: {AbortSignal}

### Class: `AbortSignal`

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* Extends: {EventTarget}

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

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

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* `reason` {any}
* Returns: {AbortSignal}

Returns a new already aborted `AbortSignal`.

#### Static method: `AbortSignal.timeout(delay)`

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* `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)`

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* `signals` {AbortSignal\[]} The `AbortSignal`s 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'`

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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'`:

```js
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`

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* Type: {boolean} True after the `AbortController` has been aborted.

#### `abortSignal.onabort`

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* 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`

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* Type: {any}

An optional reason specified when the `AbortSignal` was triggered.

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

#### `abortSignal.throwIfAborted()`

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

## Class: `Blob`

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See {Blob}.

## Class: `Buffer`

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* Type: {Function}

Used to handle binary data. See the [buffer section][].

## Class: `ByteLengthQueuingStrategy`

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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)`

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

Global alias for [`buffer.atob()`][].

## Class: `BroadcastChannel`

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See {BroadcastChannel}.

## `btoa(data)`

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

Global alias for [`buffer.btoa()`][].

## `clearImmediate(immediateObject)`

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[`clearImmediate`][] is described in the [timers][] section.

## `clearInterval(intervalObject)`

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[`clearInterval`][] is described in the [timers][] section.

## `clearTimeout(timeoutObject)`

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[`clearTimeout`][] is described in the [timers][] section.

## Class: `CompressionStream`

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A browser-compatible implementation of [`CompressionStream`][].

## `console`

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* Type: {Object}

Used to print to stdout and stderr. See the [`console`][] section.

## Class: `CountQueuingStrategy`

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A browser-compatible implementation of [`CountQueuingStrategy`][].

## Class: `Crypto`

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> Stability: 1 - Experimental. Disable this API with the
> [`--no-experimental-global-webcrypto`][] CLI flag.

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`

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> Stability: 1 - Experimental. Disable this API with the
> [`--no-experimental-global-webcrypto`][] CLI flag.

A browser-compatible implementation of the [Web Crypto API][].

## Class: `CryptoKey`

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> Stability: 1 - Experimental. Disable this API with the
> [`--no-experimental-global-webcrypto`][] CLI flag.

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`

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    pr-url: https://github.com/nodejs/node/pull/44860
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-->

A browser-compatible implementation of {CustomEvent}.

## Class: `DecompressionStream`

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A browser-compatible implementation of [`DecompressionStream`][].

## Class: `Event`

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

## Class: `EventSource`

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> Stability: 1 - Experimental. Enable this API with the [`--experimental-eventsource`][]
> CLI flag.

A browser-compatible implementation of {EventSource}.

## Class: `EventTarget`

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-->

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`

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    description: No longer experimental.
  - version: v18.0.0
    pr-url: https://github.com/nodejs/node/pull/41811
    description: No longer behind `--experimental-fetch` CLI flag.
-->

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

```mjs
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](https://undici.nodejs.org), 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](https://undici.nodejs.org/#/docs/api/Dispatcher.md).

```js
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.

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

### Related classes

The following globals are available to use with `fetch`:

* [`FormData`](https://nodejs.org/api/globals.html#class-formdata)
* [`Headers`](https://nodejs.org/api/globals.html#class-headers)
* [`Request`](https://nodejs.org/api/globals.html#request)
* [`Response`](https://nodejs.org/api/globals.html#response).

## Class: `File`

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See {File}.

## Class: `FormData`

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    description: No longer experimental.
  - version: v18.0.0
    pr-url: https://github.com/nodejs/node/pull/41811
    description: No longer behind `--experimental-fetch` CLI flag.
-->

A browser-compatible implementation of {FormData}.

## `global`

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> Stability: 3 - Legacy. Use [`globalThis`][] instead.

* 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`

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    description: No longer experimental.
  - version: v18.0.0
    pr-url: https://github.com/nodejs/node/pull/41811
    description: No longer behind `--experimental-fetch` CLI flag.
-->

A browser-compatible implementation of {Headers}.

## `localStorage`

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> 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.

## Class: `MessageChannel`

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The `MessageChannel` class. See [`MessageChannel`][] for more details.

## Class: `MessageEvent`

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A browser-compatible implementation of {MessageEvent}.

## Class: `MessagePort`

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The `MessagePort` class. See [`MessagePort`][] for more details.

## `module`

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

## Class: `Navigator`

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> Stability: 1.1 - Active development. Disable this API with the
> [`--no-experimental-global-navigator`][] CLI flag.

A partial implementation of the [Navigator API][].

## `navigator`

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> Stability: 1.1 - Active development. Disable this API with the
> [`--no-experimental-global-navigator`][] CLI flag.

A partial implementation of [`window.navigator`][].

### `navigator.hardwareConcurrency`

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* Type: {number}

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

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

### `navigator.language`

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* Type: {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'`.

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

### `navigator.languages`

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* Type: {Array<string>}

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']`.

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

### `navigator.platform`

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* Type: {string}

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

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

### `navigator.userAgent`

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* Type: {string}

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

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

## Class: `PerformanceEntry`

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The `PerformanceEntry` class. See [`PerformanceEntry`][] for more details.

## Class: `PerformanceMark`

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The `PerformanceMark` class. See [`PerformanceMark`][] for more details.

## Class: `PerformanceMeasure`

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The `PerformanceMeasure` class. See [`PerformanceMeasure`][] for more details.

## Class: `PerformanceObserver`

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The `PerformanceObserver` class. See [`PerformanceObserver`][] for more details.

## Class: `PerformanceObserverEntryList`

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The `PerformanceObserverEntryList` class. See
[`PerformanceObserverEntryList`][] for more details.

## Class: `PerformanceResourceTiming`

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The `PerformanceResourceTiming` class. See [`PerformanceResourceTiming`][] for
more details.

## `performance`

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The [`perf_hooks.performance`][] object.

## `process`

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* Type: {Object}

The process object. See the [`process` object][] section.

## `queueMicrotask(callback)`

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* `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.

```js
// 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`

<!-- YAML
added: v18.0.0
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 - version: v22.15.0
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   description: Marking the API stable.
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A browser-compatible implementation of [`ReadableByteStreamController`][].

## Class: `ReadableStream`

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   description: Marking the API stable.
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A browser-compatible implementation of [`ReadableStream`][].

## Class: `ReadableStreamBYOBReader`

<!-- YAML
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   description: Marking the API stable.
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A browser-compatible implementation of [`ReadableStreamBYOBReader`][].

## Class: `ReadableStreamBYOBRequest`

<!-- YAML
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   description: Marking the API stable.
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A browser-compatible implementation of [`ReadableStreamBYOBRequest`][].

## Class: `ReadableStreamDefaultController`

<!-- YAML
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A browser-compatible implementation of [`ReadableStreamDefaultController`][].

## Class: `ReadableStreamDefaultReader`

<!-- YAML
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   description: Marking the API stable.
-->

A browser-compatible implementation of [`ReadableStreamDefaultReader`][].

## `require()`

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

## Class: `Response`

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    description: No longer experimental.
  - version: v18.0.0
    pr-url: https://github.com/nodejs/node/pull/41811
    description: No longer behind `--experimental-fetch` CLI flag.
-->

A browser-compatible implementation of {Response}.

## Class: `Request`

<!-- YAML
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  - v16.15.0
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    description: No longer experimental.
  - version: v18.0.0
    pr-url: https://github.com/nodejs/node/pull/41811
    description: No longer behind `--experimental-fetch` CLI flag.
-->

A browser-compatible implementation of {Request}.

## `sessionStorage`

<!-- YAML
added: v22.4.0
-->

> 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])`

<!-- YAML
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[`setImmediate`][] is described in the [timers][] section.

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

<!-- YAML
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[`setInterval`][] is described in the [timers][] section.

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

<!-- YAML
added: v0.0.1
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[`setTimeout`][] is described in the [timers][] section.

## Class: `Storage`

<!-- YAML
added: v22.4.0
-->

> Stability: 1.0 - Early development. Enable this API with the
> [`--experimental-webstorage`][] CLI flag.

A browser-compatible implementation of {Storage}.

## `structuredClone(value[, options])`

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The WHATWG [`structuredClone`][] method.

## Class: `SubtleCrypto`

<!-- YAML
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  - v16.15.0
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  - version: v19.0.0
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    description: No longer behind `--experimental-global-webcrypto` CLI flag.
-->

> Stability: 1 - Experimental. Disable this API with the
> [`--no-experimental-global-webcrypto`][] CLI flag.

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: `DOMException`

<!-- YAML
added: v17.0.0
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The WHATWG {DOMException} class.

## Class: `TextDecoder`

<!-- YAML
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The WHATWG `TextDecoder` class. See the [`TextDecoder`][] section.

## Class: `TextDecoderStream`

<!-- YAML
added: v18.0.0
changes:
 - version: v22.15.0
   pr-url: https://github.com/nodejs/node/pull/57510
   description: Marking the API stable.
-->

A browser-compatible implementation of [`TextDecoderStream`][].

## Class: `TextEncoder`

<!-- YAML
added: v11.0.0
-->

The WHATWG `TextEncoder` class. See the [`TextEncoder`][] section.

## Class: `TextEncoderStream`

<!-- YAML
added: v18.0.0
changes:
 - version: v22.15.0
   pr-url: https://github.com/nodejs/node/pull/57510
   description: Marking the API stable.
-->

A browser-compatible implementation of [`TextEncoderStream`][].

## Class: `TransformStream`

<!-- YAML
added: v18.0.0
changes:
 - version: v22.15.0
   pr-url: https://github.com/nodejs/node/pull/57510
   description: Marking the API stable.
-->

A browser-compatible implementation of [`TransformStream`][].

## Class: `TransformStreamDefaultController`

<!-- YAML
added: v18.0.0
changes:
 - version: v22.15.0
   pr-url: https://github.com/nodejs/node/pull/57510
   description: Marking the API stable.
-->

A browser-compatible implementation of [`TransformStreamDefaultController`][].

## Class: `URL`

<!-- YAML
added: v10.0.0
-->

The WHATWG `URL` class. See the [`URL`][] section.

## Class: `URLSearchParams`

<!-- YAML
added: v10.0.0
-->

The WHATWG `URLSearchParams` class. See the [`URLSearchParams`][] section.

## Class: `WebAssembly`

<!-- YAML
added: v8.0.0
-->

* Type: {Object}

The object that acts as the namespace for all W3C
[WebAssembly][webassembly-org] related functionality. See the
[Mozilla Developer Network][webassembly-mdn] for usage and compatibility.

## Class: `WebSocket`

<!-- YAML
added:
  - v21.0.0
  - v20.10.0
changes:
  - version: v22.4.0
    pr-url: https://github.com/nodejs/node/pull/53352
    description: No longer experimental.
  - version: v22.0.0
    pr-url: https://github.com/nodejs/node/pull/51594
    description: No longer behind `--experimental-websocket` CLI flag.
-->

A browser-compatible implementation of {WebSocket}. Disable this API
with the [`--no-experimental-websocket`][] CLI flag.

## Class: `WritableStream`

<!-- YAML
added: v18.0.0
changes:
 - version: v22.15.0
   pr-url: https://github.com/nodejs/node/pull/57510
   description: Marking the API stable.
-->

A browser-compatible implementation of [`WritableStream`][].

## Class: `WritableStreamDefaultController`

<!-- YAML
added: v18.0.0
changes:
 - version: v22.15.0
   pr-url: https://github.com/nodejs/node/pull/57510
   description: Marking the API stable.
-->

A browser-compatible implementation of [`WritableStreamDefaultController`][].

## Class: `WritableStreamDefaultWriter`

<!-- YAML
added: v18.0.0
changes:
 - version: v22.15.0
   pr-url: https://github.com/nodejs/node/pull/57510
   description: Marking the API stable.
-->

A browser-compatible implementation of [`WritableStreamDefaultWriter`][].

[CommonJS module]: modules.md
[CommonJS modules]: modules.md
[ECMAScript module]: esm.md
[Navigator API]: https://html.spec.whatwg.org/multipage/system-state.html#the-navigator-object
[RFC 5646]: https://www.rfc-editor.org/rfc/rfc5646.txt
[Web Crypto API]: webcrypto.md
[`--experimental-eventsource`]: cli.md#--experimental-eventsource
[`--experimental-webstorage`]: cli.md#--experimental-webstorage
[`--localstorage-file`]: cli.md#--localstorage-filefile
[`--no-experimental-global-navigator`]: cli.md#--no-experimental-global-navigator
[`--no-experimental-global-webcrypto`]: cli.md#--no-experimental-global-webcrypto
[`--no-experimental-websocket`]: cli.md#--no-experimental-websocket
[`ByteLengthQueuingStrategy`]: webstreams.md#class-bytelengthqueuingstrategy
[`CompressionStream`]: webstreams.md#class-compressionstream
[`CountQueuingStrategy`]: webstreams.md#class-countqueuingstrategy
[`DecompressionStream`]: webstreams.md#class-decompressionstream
[`EventTarget` and `Event` API]: events.md#eventtarget-and-event-api
[`MessageChannel`]: worker_threads.md#class-messagechannel
[`MessagePort`]: worker_threads.md#class-messageport
[`PerformanceEntry`]: perf_hooks.md#class-performanceentry
[`PerformanceMark`]: perf_hooks.md#class-performancemark
[`PerformanceMeasure`]: perf_hooks.md#class-performancemeasure
[`PerformanceObserverEntryList`]: perf_hooks.md#class-performanceobserverentrylist
[`PerformanceObserver`]: perf_hooks.md#class-performanceobserver
[`PerformanceResourceTiming`]: perf_hooks.md#class-performanceresourcetiming
[`ReadableByteStreamController`]: webstreams.md#class-readablebytestreamcontroller
[`ReadableStreamBYOBReader`]: webstreams.md#class-readablestreambyobreader
[`ReadableStreamBYOBRequest`]: webstreams.md#class-readablestreambyobrequest
[`ReadableStreamDefaultController`]: webstreams.md#class-readablestreamdefaultcontroller
[`ReadableStreamDefaultReader`]: webstreams.md#class-readablestreamdefaultreader
[`ReadableStream`]: webstreams.md#class-readablestream
[`TextDecoderStream`]: webstreams.md#class-textdecoderstream
[`TextDecoder`]: util.md#class-utiltextdecoder
[`TextEncoderStream`]: webstreams.md#class-textencoderstream
[`TextEncoder`]: util.md#class-utiltextencoder
[`TransformStreamDefaultController`]: webstreams.md#class-transformstreamdefaultcontroller
[`TransformStream`]: webstreams.md#class-transformstream
[`URLSearchParams`]: url.md#class-urlsearchparams
[`URL`]: url.md#class-url
[`WritableStreamDefaultController`]: webstreams.md#class-writablestreamdefaultcontroller
[`WritableStreamDefaultWriter`]: webstreams.md#class-writablestreamdefaultwriter
[`WritableStream`]: webstreams.md#class-writablestream
[`__dirname`]: modules.md#__dirname
[`__filename`]: modules.md#__filename
[`abortSignal.reason`]: #abortsignalreason
[`buffer.atob()`]: buffer.md#bufferatobdata
[`buffer.btoa()`]: buffer.md#bufferbtoadata
[`clearImmediate`]: timers.md#clearimmediateimmediate
[`clearInterval`]: timers.md#clearintervaltimeout
[`clearTimeout`]: timers.md#cleartimeouttimeout
[`console`]: console.md
[`exports`]: modules.md#exports
[`fetch()`]: https://developer.mozilla.org/en-US/docs/Web/API/fetch
[`globalThis`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/globalThis
[`localStorage`]: https://developer.mozilla.org/en-US/docs/Web/API/Window/localStorage
[`module`]: modules.md#module
[`perf_hooks.performance`]: perf_hooks.md#perf_hooksperformance
[`process.nextTick()`]: process.md#processnexttickcallback-args
[`process` object]: process.md#process
[`require()`]: modules.md#requireid
[`sessionStorage`]: https://developer.mozilla.org/en-US/docs/Web/API/Window/sessionStorage
[`setImmediate`]: timers.md#setimmediatecallback-args
[`setInterval`]: timers.md#setintervalcallback-delay-args
[`setTimeout`]: timers.md#settimeoutcallback-delay-args
[`structuredClone`]: https://developer.mozilla.org/en-US/docs/Web/API/structuredClone
[`window.navigator`]: https://developer.mozilla.org/en-US/docs/Web/API/Window/navigator
[buffer section]: buffer.md
[built-in objects]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects
[timers]: timers.md
[webassembly-mdn]: https://developer.mozilla.org/en-US/docs/WebAssembly
[webassembly-org]: https://webassembly.org
