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.

Note: This feature is available in Web Workers.

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
# dom-websocket-onopen

Browser compatibility

desktopmobileserver
Chrome
Edge
Firefox
Opera
Safari
Chrome Android
Firefox for Android
Opera Android
Safari on iOS
Samsung Internet
WebView Android
WebView on iOS
Deno
Node.js
open event

See also