iframe-navigations.html

<script>
  var iframe = document.createElement('iframe');
  var sameOriginURL = 'index.html';
  var crossOriginURL = 'https://example.com';
</script>
<header>
  <button onclick="iframe.src = crossOriginURL; document.body.append(iframe)">
    Append iframe with a cross-origin URL
  </button>
  <button onclick="iframe.src = sameOriginURL; document.body.append(iframe)">
    Append iframe with a same-origin URL
  </button>
  <button onclick="iframe.src = sameOriginURL;">
    Navigate iframe to a same-origin URL
  </button>
  <button onclick="iframe.src = crossOriginURL;">
    Navigate iframe to a cross-origin URL
  </button>
  <button onclick="iframe.remove();">
    Remove iframe
  </button>
</header>