ExtendableMessageEvent: source property
Baseline
Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since April 2018.
Note: This feature is only available in Service Workers.
The source read-only property of the
ExtendableMessageEvent interface returns a reference to the
Client object from which the message was sent.
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 an ExtendableMessageEvent.
js
let port;
self.addEventListener("push", (e) => {
const 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 = (e) => {
console.log(e.source);
port = e.ports[0];
};
Specifications
| Specification |
|---|
| Service Workers Nightly # extendablemessage-event-source |
Browser compatibility
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Legend
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- Full support
- Full support
- No support
- No support