components/test/data/actor/two_iframes.html

<!DOCTYPE html>
<html>
  <head>
    <meta name="viewport" content="width=device-width,minimum-scale=1">
    <title>Two cross origin iframe Test Case</title>
    <style>
      iframe {
        position: absolute;
        width: 50vw;
        height: 50vh;
        top: 0;
        left: 0;
        border: 0;
      }
      #topframe {
        z-index: 5;
        background-color: darkred;
      }
      #bottomframe {
        z-index: 1;
        background-color:lightblue;
      }
    </style>
  </head>
  <iframe id="topframe"></iframe>
  <iframe id="bottomframe"></iframe>
  <script>
    const topframe = document.getElementById('topframe');
    const bottomframe = document.getElementById('bottomframe');

    let topframeLoaded = false;
    let bottomframeLoaded = false;

    topframe.addEventListener('load', () => {
        topframeLoaded = true;
    });

    bottomframe.addEventListener('load', () => {
        bottomframeLoaded = true;
    });
  </script>
</html>