<!DOCTYPE html>
<html lang="en-US">
<head>
<style>
#send{
padding:5px;
margin-bottom:10px;
}
#receiver{
width:500px;
height:200px;
display:block;
}
</style>
</head>
<body>
<button id="send">Send Message</button>
<iframe id="receiver" src="https://www.2braces.com/data-structures/demo">
<p>Your browser does not support iframes.</p>
</iframe>
<script>
window.onload = function(){
var btn = document.getElementById('send');
var receiver = document.getElementById('receiver').contentWindow;
function sendMessage(e) {
e.preventDefault();
receiver.postMessage('Hello Wikimass.com!', 'https://www.2braces.com');
}
btn.addEventListener('click', sendMessage);
}
</script> </body>
</html>