observe-random-namespace.html

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This WPT test may be referenced by the following Test IDs:
- /largest-contentful-paint/observe-random-namespace.html - WPT Dashboard Interop Dashboard

<!DOCTYPE HTML>

<meta charset=utf-8>

<title>Largest Contentful Paint: observe element created in a random namespace</title>

<body>

<script src="/resources/testharness.js"></script>

<script src="/resources/testharnessreport.js"></script>

<script src="resources/largest-contentful-paint-helpers.js"></script>

<style>

  div {

    display: block;

</style>

<script>

  async_test(function (t) {

    assert_implements(window.LargestContentfulPaint, "LargestContentfulPaint is not implemented");

    let beforeRender;

    const observer = new PerformanceObserver(

      t.step_func_done(function(entryList) {

        assert_equals(entryList.getEntries().length, 1);

        const entry = entryList.getEntries()[0];

        assert_equals(entry.entryType, 'largest-contentful-paint');

        assert_greater_than_equal(entry.renderTime, beforeRender);

        assert_greater_than_equal(performance.now(), entry.renderTime);

        assert_approx_equals(entry.startTime, entry.renderTime, 0.001,

          'startTime should be equal to renderTime to the precision of 1 millisecond.');

        assert_equals(entry.duration, 0);

        // Some lower bound: height of at least 12 px.

        // Width of at least 100 px.

        assert_greater_than(entry.size, 1200);

        assert_equals(entry.loadTime, 0);

        assert_equals(entry.url, '');

        assert_equals(entry.id, 'my_text');

        assert_equals(entry.element, document.getElementById("my_text"));

})

);

    observer.observe({type: 'largest-contentful-paint', buffered: true});

    const div = document.createElementNS("random", "div");

    div.innerHTML = "This is important text! :)";

    div.id = "my_text";

    beforeRender = performance.now();

    document.body.appendChild(div);

  }, 'Element created with different namespace is observable');

</script>

</body>