ExtendableMessageEvent.lastEventId

This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

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

Syntax

var myLastEventId = ExtendableMessageEventInstance.lastEventId;

Value

A DOMString.

Examples

When the following code is used inside a service worker to respond to a push messages by sending the data received via PushMessageData to the main context via a channel message, the event object of onmessage will be a ExtendableMessageEvent.

var port;

self.addEventListener('push', function(e) {
  var obj = e.data.json();

  if(obj.action === 'subscribe' || obj.action === 'unsubscribe') {
    port.postMessage(obj);
  } else if(obj.action === 'init' || obj.action === 'chatMsg') {
    port.postMessage(obj);
  }
});

self.onmessage = function(e) {
  console.log(e.lastEventId);
  port = e.ports[0];
}

Specifications

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

Browser compatibility

Update compatibility data on GitHub
DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidEdge MobileFirefox for AndroidOpera for AndroidiOS SafariSamsung Internet
Basic support
Experimental
Chrome ? Edge Full support 17Firefox Full support 45
Notes
Full support 45
Notes
Notes Service workers (and Push) have been disabled in the Firefox 45 & 52 Extended Support Releases (ESR).
IE ? Opera ? Safari No support NoWebView Android No support NoChrome Android ? Edge Mobile Full support 17Firefox Android Full support 45Opera Android ? Safari iOS No support NoSamsung Internet Android ?

Legend

Full support  
Full support
No support  
No support
Compatibility unknown  
Compatibility unknown
Experimental. Expect behavior to change in the future.
Experimental. Expect behavior to change in the future.
See implementation notes.
See implementation notes.

See also

Document Tags and Contributors

Contributors to this page: fscholz, xramnz, chrisdavidmills
Last updated by: fscholz,