element-timing/observe-empty-attribute.html

<!DOCTYPE HTML>
<meta charset=utf-8>
<title>Element Timing: observe with empty elementtiming attribute</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="resources/element-timing-helpers.js"></script>
<script>
let beforeRender;
async_test(function (t) {
  assert_implements(window.PerformanceElementTiming, "PerformanceElementTiming is not implemented");
  let observedImage = false;
  let observedText = false;
  const observer = new PerformanceObserver(
    t.step_func(function(entryList) {
      entryList.getEntries().forEach(entry => {
        if (entry.name === 'image-paint') {
          assert_false(observedImage, 'Image should only be observed once.');
          const pathname = window.location.origin + '/element-timing/resources/square20.png';
          checkElement(entry, pathname, '', 'square', beforeRender,
              document.getElementById('square'));
          checkNaturalSize(entry, 20, 20);
          observedImage = true;
        } else {
          assert_false(observedText, 'Text should only be observed once.');
          checkTextElement(entry, '', 'text', beforeRender, document.getElementById('text'));
          observedText = true;
        }
      });
      if (observedImage && observedText)
        t.done();
    })
  );
  observer.observe({type: 'element', buffered: true});
  beforeRender = performance.now();
}, "Able to observe image and text with empty elementtiming attribute.");
</script>
<img id='square' src='resources/square20.png' elementtiming/>
<p id='text' elementtiming>Text!</p>