demo.html

<!DOCTYPE html>
<html>
<head>
  <script src="src/snippet.js"></script>
  <script>
  const url = 'https://upload.wikimedia.org' +
      '/wikipedia/commons/3/3f/Fronalpstock_big.jpg';

  var oReq = new XMLHttpRequest();
  oReq.addEventListener('load', () => console.log('window loaded'));
  oReq.open('GET', url);
  oReq.send('test');

  setTimeout(() => fetch(url), 1000);

  setTimeout(() => {
    const start = performance.now();
    while (performance.now() < start + 60);
  }, 1500);
  </script>
<style>
</style>
</head>
<body>
  <script src="tti-polyfill-debug.js"></script>
  <script>
  ttiPolyfill.getFirstConsistentlyInteractive().then(console.log);
  </script>
</body>
</html>