How to automatically resize an iframe based on their content

embed-script.html

<script type="text/javascript">
 var node = document.scripts[document.scripts.length - 1];
 var parent = node.parentElement;
 var iframe = document.createElement('iframe');
 iframe.setAttribute('src', 'http://example.com');
 iframe.width = '100%';
 iframe.frameBorder = 0;
 parent.insertBefore(iframe, node.nextSibling);
 window.addEventListener('message', function(e){ iframe.height = e.data }, false);
</script>

embeddable.js

// Add to the page that needs to be embedded.
if(parent.postMessage) {
  var refresh = setInterval(() => parent.postMessage(document.body.scrollHeight, '*'), 500);
}