Web/API/Worker/message event

The message event is fired on a Worker object when the worker's parent receives a message from its worker (i.e. when the worker sends a message using DedicatedWorkerGlobalScope.postMessage()).

Bubbles	No
Cancelable	No
Interface	MessageEvent
Event handler property	onmessage

Examples

This code creates a new worker and listens to messages from it using addEventListener():

const worker = new Worker("static/scripts/worker.js");

worker.addEventListener('message', (event) => {
    console.log(`Received message from worker: ${event.data}`)
});

Alternatively, it could listen using the onmessage event handler property:

const worker = new Worker("static/scripts/worker.js");

worker.onmessage = (event) => {
    console.log(`Received message from worker: ${event.data}`)
};

The worker posts messages using self.postMessage():

// static/scripts/worker.js

self.postMessage('I\'m alive!');

Specifications

Specification	Status
HTML Living Standard	Living Standard

Browser compatibility

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.

Update compatibility data on GitHub

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
message event	Chrome Full support 4	Edge Full support 12	Firefox Full support 3.5	IE Full support 10	Opera Full support 10.6	Safari Full support 4	WebView Android Full support 4	Chrome Android Full support 18	Firefox Android Full support 4	Opera Android Full support 11.5	Safari iOS Full support 5.1	Samsung Internet Android Full support 1.0

Legend

Full support  

Full support

See also

• Related events: messageerror.
• DedicatedWorkerGlobalScope.postMessage().

Worker: message event by Mozilla Contributors is licensed under CC-BY-SA 2.5.