css/css-transitions/disconnected-element-001.html

<!doctype html>
<html>
<head>
<meta charset=utf-8>
<title>CSS Transitions Test: Transitions do not run for a disconnected element</title>
<meta name="assert" content="If an element is not in the document during that
style change event or was not in the document during the previous style change
event, then transitions are not started for that element in that style change
event.">
<meta name="assert" content="If an element is no longer in the document,
implementations must cancel any running transitions on it and remove transitions
on it from the completed transitions.">
<link rel="help" title="Starting transitions"
  href="https://drafts.csswg.org/css-transitions/#starting">

<script src="/resources/testharness.js" type="text/javascript"></script>
<script src="/resources/testharnessreport.js" type="text/javascript"></script>
<script src="./support/helper.js" type="text/javascript"></script>

</head>
<body>
<div id="log"></div>

<script>
promise_test(async t => {
  // Create element and remove it from the document
  const div = addDiv(t, {
    style: 'transition: background-color 100s; background-color: red',
  });
  div.remove();

  // Attach event listeners
  div.addEventListener('transitionrun', t.step_func(() => {
    assert_unreached('transitionrun event should not be fired');
  }));

  // Resolve before-change style
  getComputedStyle(div).backgroundColor;

  // Set up and resolve after-change style
  div.style.backgroundColor = 'green';
  getComputedStyle(div).backgroundColor;

  // There should be no events received for the triggered transition.
  await waitForFrame();
  await waitForFrame();
}, 'Transitions do not run on an element not in the document');

test(t => {
  // Create element but do not attach it to the document
  const div = addDiv(t, {
    style: 'transition: background-color 100s; background-color: red',
  });
  div.remove();

  // Resolve before-change style
  getComputedStyle(div).backgroundColor;

  // Add to document
  document.documentElement.append(div);

  // Set up and resolve after-change style
  div.style.backgroundColor = 'green';
  getComputedStyle(div).backgroundColor;

  // We should have jumped immediately to the after-change style rather than
  // transitioning to it.
  assert_equals(
    getComputedStyle(div).backgroundColor,
    'rgb(0, 128, 0)',
    'No transition should run'
  );
}, 'Transitions do not run for an element newly added to the document');

promise_test(async t => {
  // Create element and attach it to the document
  const div = addDiv(t, {
    style: 'transition: background-color 100s; background-color: red',
  });

  // Attach event listeners
  div.addEventListener('transitionrun', t.step_func(() => {
    assert_unreached('transitionrun event should not be fired');
  }));

  // Resolve before-change style
  getComputedStyle(div).backgroundColor;

  // Set up after-change style
  div.style.backgroundColor = 'green';

  // But remove the document before the next style change event
  div.remove();

  // There should be no events received for the triggered transition.
  await waitForFrame();
  await waitForFrame();
}, 'Transitions do not run for an element newly removed from the document');

promise_test(async t => {
  // Create element and attach it to the document
  const div = addDiv(t, {
    style: 'transition: background-color 100s; background-color: red',
  });

  // Attach event listeners
  const eventWatcher = new EventWatcher(t, div, [
    'transitionrun',
    'transitioncancel',
  ]);

  // Trigger transition
  getComputedStyle(div).backgroundColor;
  div.style.backgroundColor = 'green';
  getComputedStyle(div).backgroundColor;

  await eventWatcher.wait_for('transitionrun');

  // Remove the element from the document
  div.remove();

  await eventWatcher.wait_for('transitioncancel');
}, 'Transitions are canceled when an element is removed from the document');

promise_test(async t => {
  // Create a container element. We'll need this later.
  const container = addDiv(t);

  // Create element and attach it to the document
  const div = addDiv(t, {
    style: 'transition: background-color 100s; background-color: red',
  });

  // Attach event listeners
  const eventWatcher = new EventWatcher(t, div, [
    'transitionrun',
    'transitioncancel',
  ]);

  // Trigger transition
  getComputedStyle(div).backgroundColor;
  div.style.backgroundColor = 'green';
  getComputedStyle(div).backgroundColor;

  await eventWatcher.wait_for('transitionrun');

  // Re-parent element
  container.append(div);

  await eventWatcher.wait_for('transitioncancel');
  assert_equals(
    getComputedStyle(div).backgroundColor,
    'rgb(0, 128, 0)',
    'There should be no transition after re-parenting'
  );
}, 'Transitions are canceled when an element is re-parented');

promise_test(async t => {
  // Create element and attach it to the document
  const div = addDiv(t, {
    style: 'transition: background-color 100s; background-color: red',
  });

  // Attach event listeners
  const eventWatcher = new EventWatcher(t, div, [
    'transitionrun',
    'transitioncancel',
  ]);

  // Trigger transition
  getComputedStyle(div).backgroundColor;
  div.style.backgroundColor = 'green';
  getComputedStyle(div).backgroundColor;

  await eventWatcher.wait_for('transitionrun');

  // Re-parent element to same parent
  document.documentElement.append(div);

  await eventWatcher.wait_for('transitioncancel');
  assert_equals(
    getComputedStyle(div).backgroundColor,
    'rgb(0, 128, 0)',
    'There should be no transition after re-parenting'
  );
}, 'Transitions are canceled when an element is re-parented to the same node');
</script>

</body>
</html>