intersection-observer/reinsert-element.html

<!DOCTYPE html>
<meta name="viewport" content="width=device-width,initial-scale=1">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="./resources/intersection-observer-test-utils.js"></script>

<style>
pre, #log {
  position: absolute;
  top: 0;
  left: 200px;
}
</style>

<div id="target">Hello, world!</div>

<script>
promise_test(async function(t) {
  let entries = [];
  let target = document.getElementById("target");
  let observer = new IntersectionObserver(function(changes) {
    entries = entries.concat(changes);
  });
  observer.observe(target);
  await waitForNotification();
  assert_equals(entries.length, 1);
  assert_true(entries[0].isIntersecting);
  target.remove();
  document.body.appendChild(target);
  await waitForNotification();
  assert_equals(entries.length, 1);
  assert_true(entries[0].isIntersecting);
}, "An element that is removed and reinserted without an intervening" +
  " rendering update doesn't generate a 'not-intersecting' notification.");
</script>