IFrame and Parent Communcaiton

https://lowrey.me/communicating-between-iframes-with-window-postmessage/  

window.send = function() {

  var iframe = document.getElementById('jsfiddle-frame').contentWindow;

  var message = document.querySelector('#textOutput').value;

  iframe.postMessage(message, '*');

}

window.addEventListener('message', function(event) {

  document.querySelector('#textOutput').value = event.data;

}, false);