WebSocket: message event

The message event is fired when data is received through a WebSocket.

Syntax

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

addEventListener('message', event => { })

onmessage = event => { }

Event type

An MessageEvent. Inherits from Event.

Event properties

In addition to the properties listed below, properties from the parent interface, Event, are available.

data Read only: The data sent by the message emitter.
origin Read only: A USVString representing the origin of the message emitter.
lastEventId Read only: A DOMString representing a unique ID for the event.
source Read only: A MessageEventSource (which can be a Window, MessagePort, or ServiceWorker object) representing the message emitter.
ports Read only: An array of MessagePort objects representing the ports associated with the channel the message is being sent through (where appropriate, e.g. in channel messaging or when sending a message to a shared worker).

Examples

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

// Listen for messages
socket.addEventListener('message', function (event) {
    console.log('Message from server ', event.data);
});

Specifications

Specification
HTML Standard # event-message
HTML Standard # handler-websocket-onmessage

Browser compatibility

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