WebSocketStream: closed property

Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

Note: This feature is available in Web Workers.

The closed read-only property of the WebSocketStream interface returns a Promise that fulfills with an object once the socket connection is closed. The object contains the closing code and reason.

Value

A promise, which fulfills with an object containing the following properties:

closeCode

A number representing the closing code (see the full list of CloseEvent status codes).

reason

A string representing a human-readable description of the reason why the socket connection was closed.

The promise rejects if the WebSocket connection did not close cleanly (for a clean close, the associated TCP connection must be closed after the WebSocket closing handshake is completed).

Examples

js
const wsURL = "wss://127.0.0.1/";
const wss = new WebSocketStream(wsURL);

wss.closed.then((result) => {
  writeToScreen(
    `DISCONNECTED: code ${result.closeCode}, message "${result.reason}"`,
  );
  console.log("Socket closed", result.closeCode, result.reason);
});

See Using WebSocketStream to write a client for a complete example with full explanation.

Specifications

Not currently a part of any specification. See https://github.com/whatwg/websockets/pull/48 for standardization progress.

Browser compatibility

Report problems with this compatibility data on GitHub
desktopmobile
Chrome
Edge
Firefox
Opera
Safari
Chrome Android
Firefox for Android
Opera Android
Safari on iOS
Samsung Internet
WebView Android
WebView on iOS
closed
Experimental

Legend

Tip: you can click/tap on a cell for more information.

Full support
Full support
No support
No support
Experimental. Expect behavior to change in the future.

See also