ExtendableMessageEvent

The ExtendableMessageEvent interface of the Service Worker API represents the event object of a message event fired on a service worker (when a message is received on the ServiceWorkerGlobalScope from another context) — extends the lifetime of such events.

This interface inherits from the ExtendableEvent interface.

Constructor

ExtendableMessageEvent()
Creates a new ExtendableMessageEvent object instance.

Properties

Inherits properties from its parent, ExtendableEvent.

ExtendableMessageEvent.data Read only
Returns the event's data. It can be any data type.
ExtendableMessageEvent.origin Read only
Returns the origin of the Client that sent the message.
ExtendableMessageEvent.lastEventId Read only
Represents, in server-sent events, the last event ID of the event source. This is an empty string.
ExtendableMessageEvent.source Read only
Returns a reference to the Client object that sent the message.
ExtendableMessageEvent.ports Read only
Returns the array containing the MessagePort objects representing the ports of the associated message channel.

Methods

Inherits methods from its parent, ExtendableEvent.

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 Comment
Service Workers
The definition of 'ExtendableMessageEvent' in that specification.
Working Draft Initial definition.

Browser compatibility

BCD tables only load in the browser

See also