WebSocket: open event

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 open event is fired when a connection with a WebSocket is opened.

Syntax

Use the event name in methods like addEventListener(), or set an event handler property.

js
addEventListener("open", (event) => {});

onopen = (event) => {};

Event type

A generic Event.

Examples

js
// Create WebSocket connection.
const socket = new WebSocket("ws://localhost:8080");

// Connection opened
socket.addEventListener("open", (event) => {
  socket.send("Hello Server!");
});

Specifications

Specification
WebSockets Standard
# dom-websocket-onopen

Browser compatibility

Desktop Mobile
Chrome Edge Firefox Opera Safari Chrome Android Firefox for Android Opera Android Safari on IOS Samsung Internet WebView Android
open_event 5 12 7 12.1 5 18 7 12.1 4.2 1.0 ≤37

See also

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Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/API/WebSocket/open_event