Note: This feature is only available in Service Workers.
The ports read-only property of the ExtendableMessageEvent interface returns the array containing the MessagePort objects representing the ports of the associated message channel (the channel the message is being sent through.)
An array of MessagePort objects.
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.
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) => {
port = e.ports[0];
};