ServiceWorkerMessageEvent.lastEventId

Deprecated
This feature has been removed from the Web standards. Though some browsers may still support it, it is in the process of being dropped. 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.

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

The lastEventID read-only property of the ServiceWorkerMessageEvent interface represents, in server-sent events, the last event ID of the event source.

Syntax

var myLastEventId = ServiceWorkerMessageEventInstance.lastEventId;

Value

A DOMString.

Examples

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) {
        console.log(e.lastEventId);
        handleChannelMessage(e.data);
      }
      
      mySW = reg.active;
      mySW.postMessage('hello', [channel.port2]);
  });

Specifications

Specification Status Comment
Service Workers
The definition of 'ServiceWorkerMessageEvent.lastEventId' in that specification.
Working Draft Initial definition.

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support 45.0 44.0 (44.0)[1] No support 24 No support
Deprecated in favour of MessageEvent ? 55.0 (55.0) No support ? No support
Feature Android Android Webview Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile Chrome for Android
Basic support No support No support (Yes) No support ? No support 45.0
Deprecated in favour of MessageEvent No support No support (Yes) No support ? No support ?

[1] Service workers (and Push) have been disabled in the Firefox 45 and 52 Extended Support Releases (ESR.)

See also

Document Tags and Contributors

 Contributors to this page: chrisdavidmills, narohcp
 Last updated by: chrisdavidmills,