 elm = document.getElementById('testIsTypeSupported');
            const isTypeSupported = MediaSource.isTypeSupported(
              'video/mp4; codecs="avc1.42E01E, mp4a.40.2"'
            );
            elm.textContent = String(isTypeSupported);
          })();
        </script>
      </li>

      <li>
        <strong>addEventListener('load')</strong>
        <code id="testWindowLoad"></code>
        <script type="text/partytown">
          (function () {
            const elm = document.getElementById('