xref: /third_party/node/deps/undici/src/docs/api/WebSocket.md

# Class: WebSocket

> ⚠️ Warning: the WebSocket API is experimental.

Extends: [`EventTarget`](https://developer.mozilla.org/en-US/docs/Web/API/EventTarget)

The WebSocket object provides a way to manage a WebSocket connection to a server, allowing bidirectional communication. The API follows the [WebSocket spec](https://developer.mozilla.org/en-US/docs/Web/API/WebSocket) and [RFC 6455](https://datatracker.ietf.org/doc/html/rfc6455).

## `new WebSocket(url[, protocol])`

Arguments:

* **url** `URL | string` - The url's protocol *must* be `ws` or `wss`.
* **protocol** `string | string[] | WebSocketInit` (optional) - Subprotocol(s) to request the server use, or a [`Dispatcher`](./Dispatcher.md).

### Example:

This example will not work in browsers or other platforms that don't allow passing an object.

```mjs
import { WebSocket, ProxyAgent } from 'undici'

const proxyAgent = new ProxyAgent('my.proxy.server')

const ws = new WebSocket('wss://echo.websocket.events', {
  dispatcher: proxyAgent,
  protocols: ['echo', 'chat']
})
```

If you do not need a custom Dispatcher, it's recommended to use the following pattern:

```mjs
import { WebSocket } from 'undici'

const ws = new WebSocket('wss://echo.websocket.events', ['echo', 'chat'])
```

## Read More

- [MDN - WebSocket](https://developer.mozilla.org/en-US/docs/Web/API/WebSocket)
- [The WebSocket Specification](https://www.rfc-editor.org/rfc/rfc6455)
- [The WHATWG WebSocket Specification](https://websockets.spec.whatwg.org/)