element-timing/toJSON.html

<!DOCTYPE HTML>
<meta charset=utf-8>
<title>Element Timing: toJSON</title>
<body>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="resources/element-timing-helpers.js"></script>
<img elementtiming='img' src="resources/square100.png"/>
<script>
  async_test(function (t) {
    assert_implements(window.PerformanceElementTiming, "PerformanceElementTiming is not implemented");
    const observer = new PerformanceObserver(
      t.step_func_done(function(entryList) {
        assert_equals(entryList.getEntries().length, 1);
        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',
          // PerformanceElementTiming
          'renderTime',
          'loadTime',
          'intersectionRect',
          'identifier',
          'naturalWidth',
          'naturalHeight',
          'id',
          'url',
        ];
        for (const key of keys) {
          assert_equals(json[key], entry[key],
            'PerformanceElementTiming ${key} entry does not match its toJSON value');
        }
        assert_equals(json['element'], undefined, 'toJSON should not include element');
      })
    );
    observer.observe({type: 'element', buffered: true});
  }, 'Test toJSON() in PerformanceElementTiming.');
</script>
</body>