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WebSocketStream: closed property

files/en-us/web/api/websocketstream/closed/index.md

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{{APIRef("WebSockets API")}}{{SeeCompatTable}}{{AvailableInWorkers}}

The closed read-only property of the {{domxref("WebSocketStream")}} interface returns a {{jsxref("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
  • 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

{{Compat}}

See also