Web/API/ServiceWorkerGlobalScope/message event

The message event of the ServiceWorkerGlobalScope interface occurs when incoming messages are received. Controlled pages can use the ServiceWorker.postMessage() method to send messages to service workers. The service worker can optionally send a response back via the Client.postMessage(), corresponding to the controlled page.

Bubbles	No
Cancelable	No
Interface	ExtendableMessageEvent
Event handler property	onmessage

Examples

In the below example a page gets a handle to the ServiceWorker object via ServiceWorkerRegistration.active, and then calls its postMessage() function.

// in the page being controlled
if (navigator.serviceWorker) {

  navigator.serviceWorker.register('service-worker.js');

  navigator.serviceWorker.addEventListener('message', event => {
    // event is a MessageEvent object
    console.log(`The service worker sent me a message: ${event.data}`);
  });

  navigator.serviceWorker.ready.then( registration => {
    registration.active.postMessage("Hi service worker");
  });

}

The service worker can receive the message by listening to the message event:

// in the service worker
addEventListener('message', event => {
  // event is an ExtendableMessageEvent object
  console.log(`The client sent me a message: ${event.data}`);

  event.source.postMessage("Hi client");
});

Specifications

Specification	Status
Service WorkersThe definition of 'message' in that specification.	Working Draft

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 Experimental'	Chrome Full support 40	Edge Full support ≤79	Firefox Full support 44 Notes' Full support 44 Notes' Notes' Extended Support Releases (ESR) before Firefox 78 ESR do not support service workers and the Push API.	IE No support No	Opera Full support 24	Safari Full support 11.1	WebView Android Full support 40	Chrome Android Full support 40	Firefox Android Full support 44	Opera Android Full support 24	Safari iOS Full support 11.3	Samsung Internet Android Full support 4.0

Legend

Full support  

Full support

No support  

No support

Experimental. Expect behavior to change in the future.'

Experimental. Expect behavior to change in the future.

See implementation notes.'

See implementation notes.

See also

• Using Service Workers
• Service workers basic code example
• Is ServiceWorker ready?
• Using web workers

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