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ExtendableMessageEvent: ports property

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.)

Value

An array of MessagePort objects.

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.

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) => {
  port = e.ports[0];
};

Specifications

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
ports 51 17 44 No 38 11.1 51 51 44 41 11.3 5.0

See also

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https://developer.mozilla.org/en-US/docs/Web/API/ExtendableMessageEvent/ports