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

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic support ?17451 ? ? No
FeatureAndroid webviewChrome for AndroidEdge mobileFirefox for AndroidOpera AndroidiOS SafariSamsung Internet
Basic support No ?1745 ? No ?

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

See also

Document Tags and Contributors

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