element-timing/text-with-display-style.html

<!DOCTYPE HTML>
<meta charset=utf-8>
<title>Element Timing: observe text with display style.</title>
<body>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="resources/element-timing-helpers.js"></script>
<style>
h1 {
  display: flex;
}
h2 {
  display: grid;
}
h3 {
  display: block;
}
</style>
<h1 id='title1' elementtiming='h1'>I am h1</h1>
<h2 id='title2' elementtiming='h2'>I am h2</h2>
<h3 id='title3' elementtiming='h3'>I am h3</h3>
<script>
  async_test(function (t) {
    assert_implements(window.PerformanceElementTiming, "PerformanceElementTiming is not implemented");
    const beforeRender = performance.now();
    let observedFlex = false;
    let observedGrid = false;
    let observedBlock = false;
    const observer = new PerformanceObserver(
      t.step_func(function(entryList) {
        entryList.getEntries().forEach(entry => {
          if (entry.id === 'title1') {
            assert_false(observedFlex, 'Should observe flex once');
            observedFlex = true;
            checkTextElement(entry, 'h1', 'title1', beforeRender, document.getElementById('title1'));
          } else if (entry.id === 'title2') {
            assert_false(observedGrid, 'Should observe grid once');
            observedGrid = true;
            checkTextElement(entry, 'h2', 'title2', beforeRender, document.getElementById('title2'));
          } else {
            assert_equals(entry.id, 'title3', 'ID should be title1, title2, or title3');
            assert_false(observedBlock, 'Should observe block once');
            observedBlock = true;
            checkTextElement(entry, 'h3', 'title3', beforeRender, document.getElementById('title3'));
          }
        });
        if (observedFlex && observedGrid && observedBlock)
          t.done();
      })
    );
    observer.observe({type: 'element', buffered: true});
  }, 'Text with display style is observable.');
</script>
</body>