index.html

<style>
#content {
  width: 700px; Height: 300px;
  border: 1px solid black;
}
</style>

<div id="ifrm">
	<iframe id="content" src="/iframe-toggle-animation/iframe-spinning-cube.html"></iframe>
</div>
<input type="button" id="btn1" value="Hide / Show"/>

<script>
  var content = document.getElementById('content');
  var btn = document.getElementById('btn1');
  var box = document.getElementById('ifrm');


  btn.addEventListener('click', function (e) {
    box.style.display = box.style.display === '' ? 'none' : '';
  });
</script>