CloseEvent: reason property

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.

The reason read-only property of the CloseEvent interface returns the WebSocket connection close reason the server gave for closing the connection; that is, a concise human-readable prose explanation for the closure.

Value

A string.

Examples

The following example prints the value of reason to the console.

js
WebSocket.onclose = (event) => {
  console.log(event.reason);
};

Specifications

Specification
WebSockets Standard
# ref-for-dom-closeevent-reason②

Browser compatibility

Desktop Mobile
Chrome Edge Firefox Opera Safari Chrome Android Firefox for Android Opera Android Safari on IOS Samsung Internet WebView Android
reason 15 12 8 12.1 6 18 8 12.1 6 1.0 4.4

See also

  • RFC 6455 (the WebSocket Protocol specification)

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https://developer.mozilla.org/en-US/docs/Web/API/CloseEvent/reason