This is an experimental technology
Because this technology's specification has not stabilized, check the compatibility table for usage in various browsers. Also note that the syntax and behavior of an experimental technology is subject to change in future versions of browsers as the specification changes.
The source read-only property of the ExtendableMessageEvent returns a reference to the Client object from which the message was sent.
Syntax
var mySource = ExtendableMessageEventInstance.source;
Value
A Client, ServiceWorker or MessagePort object.
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.source);
port = e.ports[0];
}
Specifications
| Specification | Status | Comment |
|---|---|---|
| Service Workers The definition of 'ExtendableMessageEvent.source' in that specification. |
Working Draft | Initial definition. |
Browser compatibility
| Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari (WebKit) |
|---|---|---|---|---|---|
| Basic support | ? | 45.0 (45.0)[1] | No support | ? | No support |
| Feature | Android | Android Webview | Firefox Mobile (Gecko) | Firefox OS | IE Mobile | Opera Mobile | Safari Mobile | Chrome for Android |
|---|---|---|---|---|---|---|---|---|
| Basic support | No support | No support | (Yes) | (Yes) | No support | ? | No support | ? |
[1] Service workers (and Push) have been disabled in the Firefox 45 and 52 Extended Support Releases (ESR.)