placeholder-image.html | Explore in Territory

<!DOCTYPE HTML>
<meta charset=utf-8>
<title>Largest Contentful Paint: src change triggers new entry.</title>
<body>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="resources/largest-contentful-paint-helpers.js"></script>
<img src='/images/lcp-1x1.png' id='image_id' width="133" height="106"/>
<script>
  async_test(function (t) {
    assert_implements(window.LargestContentfulPaint, "LargestContentfulPaint is not implemented");
    let beforeLoad = performance.now();
    document.getElementById('image_id').src = '/images/lcp-133x106.png';
    const url = window.location.origin + '/images/lcp-133x106.png';
    const observer = new PerformanceObserver(
      t.step_func(function(entryList) {
        let entries = entryList.getEntries().filter(e => e.url === url);
        if (entries.length === 0)
          return;
        assert_equals(entries.length, 1);
        const entry = entries[0];
        const size = 133 * 106;
        checkImage(entry, url, 'image_id', size, beforeLoad);
        t.done();
      })
    );
    observer.observe({type: 'largest-contentful-paint', buffered: true});
  }, 'Largest Contentful Paint: changing src causes a new entry to be dispatched.');
</script>
</body>

chromium/third_party/blink/web_tests/external/wpt/largest-contentful-paint/placeholder-image.html