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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.

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

onopen = (event) => { }

Event type

A generic Event.

Examples

// 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