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ServiceWorkerMessageEvent.lastEventId

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 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]);
  });

Browser compatibility

Desktop Mobile
Chrome Edge Firefox Internet Explorer Opera Safari WebView Android Chrome Android Firefox for Android Opera Android Safari on IOS Samsung Internet
lastEventId
45
17
44-55
["Extended Support Releases (ESR) before Firefox 78 ESR do not support service workers and the Push API.", "In Firefox 55 and later, the standard MessageEvent interface must be used instead."]
No
24
No
No
45
44-55
24
No
4.0

See also

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Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/API/ServiceWorkerMessageEvent/lastEventId