Deprecated: This feature is no longer recommended. Though some browsers might still support it, it may have already been removed from the relevant web standards, may be in the process of being dropped, or may only be kept for compatibility purposes. Avoid using it, and update existing code if possible; see the compatibility table at the bottom of this page to guide your decision. Be aware that this feature may cease to work at any time.

Warning: In modern browsers, this interface has been deprecated. Service worker messages will now use the MessageEvent interface, for consistency with other web messaging features.

The ServiceWorkerMessageEvent interface of the ServiceWorker API contains information about an event sent to a ServiceWorkerContainer target. This extends the default message event to allow setting a ServiceWorker object as the source of a message. The event object is accessed via the handler function of a message event, when fired by a message received from a service worker.

This interface inherits from the Event interface.



Creates a new ServiceWorkerMessageEvent object instance.


Inherits properties from its parent, Event. Read only

Returns the event's data. It can be any data type.

ServiceWorkerMessageEvent.origin Read only

Returns the origin of the service worker's environment settings object.

ServiceWorkerMessageEvent.lastEventId Read only

Represents, in server-sent events, the last event ID of the event source.

ServiceWorkerMessageEvent.source Read only

Returns a reference to the service worker that sent the message.

ServiceWorkerMessageEvent.ports Read only

Returns an array of MessagePort objects.


Inherits methods from its parent, Event.


When the following code is used inside the main thread to set up a message channel between it and a service worker for sending messages between the two, the event object of onmessage will be a ServiceWorkerMessageEvent.

navigator.serviceWorker.ready.then(function(reg) {


      // set up a message channel to communicate with the SW
      var channel = new MessageChannel();
      channel.port1.onmessage = function(e) {

      mySW =;
      mySW.postMessage('hello', [channel.port2]);

Browser compatibility

BCD tables only load in the browser

See also