// Create browser compatible event handler.
var eventMethod = window.addEventListener ? "addEventListener" : "attachEvent";
var eventer = window[eventMethod];
var messageEvent = eventMethod == "attachEvent" ? "onmessage" : "message";
// Listen for a message from the iframe.
eventer(messageEvent, function(e) {
if (isNaN(e.data)) return;
// replace #sizetracker with what ever what ever iframe id you need
document.getElementById('sizetracker').style.height = e.data + 'px';
}, false);
