toJSON.html - mozsearch

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This test has a WPT meta file that expects 1 subtest issues.
This WPT test may be referenced by the following Test IDs:
- /layout-instability/toJSON.html - WPT Dashboard Interop Dashboard

<!DOCTYPE HTML>

<meta charset=utf-8>

<title>Layout Instability: toJSON</title>

<body>

<style>

#myDiv { position: relative; width: 300px; height: 100px; background: blue; }

</style>

<div id='myDiv'></div>

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

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

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

<script>

promise_test(async t => {

  assert_implements(window.LayoutShift, 'Layout Instability is not supported.');

  // Wait for the initial render to complete.

  await waitForAnimationFrames(2);

  return new Promise(resolve => {

    const observer = new PerformanceObserver(

      t.step_func(entryList => {

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

        assert_equals(typeof(entry.toJSON), 'function');

        const json = entry.toJSON();

        assert_equals(typeof(json), 'object');

        const keys = [

          // PerformanceEntry

          'name',

          'entryType',

          'startTime',

          'duration',

          // LayoutShift

          'value',

          'hadRecentInput',

          'lastInputTime',

];

        for (const key of keys) {

          assert_equals(json[key], entry[key],

            `LayoutShift ${key} entry does not match its toJSON value`);

        resolve();

})

);

    observer.observe({type: 'layout-shift'});

    document.getElementById('myDiv').style = "top: 60px";

});

}, 'Test toJSON() in LayoutShift.');

</script>

</body>