What are the MessageChannel and MessagePort Objects in HTML5?

Krantik Chavan

Answered on 6th Apr, 2018

While creating messageChannel, it internally creates two ports to sending the data and forwarded to another browsing context.

1. postMessage() − Post the message throw channel
2. start() − It sends the data
3. close() − it close the ports

In this scenario, we are sending the data from one iframe to another iframe. Here we are invoking the data in function and passing the data to DOM.

var loadHandler = function(){
   var mc, portMessageHandler;
   mc = new MessageChannel();
   window.parent.postMessage('documentAHasLoaded','https://foo.example',[mc.port2]);
   
   portMessageHandler = function(portMsgEvent){
      alert( portMsgEvent.data );
   }
   mc.port1.addEventListener('message', portMessageHandler, false);
   mc.port1.start();
}
window.addEventListener('DOMContentLoaded', loadHandler, false);