web-vitals.html | Explore in Territory

<!doctype html>
<html>
  <body>
    <script>
      function invalidateStyle() {
        const img = document.querySelector('img');
        img.setAttribute('src', './big-image.png');
        const newStyle = document.createElement('style');
        newStyle.textContent = `
          div {
              margin: 1px;
          }
        `;
        document.head.appendChild(newStyle);
    }
    function forceLayout() {
        const img = document.querySelector('img');
        const unused = img.offsetHeight;
    }

    function performActions() {
        invalidateStyle();
        forceLayout();
    }
    setTimeout(performActions, 1000)
    </script>
    <div>
      <img>
    </div>
    <div>
      text
    </div>
  </body>
</html>

chromium/third_party/blink/web_tests/http/tests/inspector-protocol/resources/web-vitals.html