Native Messaging postMessage with callback

You could add another listener to onNativeMessage to call your callback and then de-register.

Something like this, with closures:

function callbackOnId(ev, id, callback) {  var listener = ( function(port, id) {    var handler = function(msg) {      if(msg.id == id) {        ev.removeListener(handler);        callback(msg);      }    }    return handler;  })(ev, id, callback);  ev.addListener(listener);}/* ... */callbackOnId(port.onMessage, "someRequestId", callback);port.postMessage({"text":"message", "id": "someRequestId"});

Now, the first time your port receives a message containing "id": "someRequestId", callback will be called with that message, after which the listener will de-register itself.

If you need it, you can add an ability to remove the listener and/or modify the message checks.

My solution is to assign each message an unique id, and use a map to store the callback function for each message id (if there is a callback for the message).

When you receive a message from the host, check the message id and lookup the callback map. If there is a callback bound to that message, pass the response data and call it!