css/cssom-view/visual-scrollIntoView-002.html

<!DOCTYPE html>
<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/testdriver.js"></script>
<script src="/resources/testdriver-actions.js"></script>
<script src="/resources/testdriver-vendor.js"></script>
<script src="support/action-utils.js"></script>
<link rel="help" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1947470">
<link rel="help" href="https://drafts.csswg.org/cssom-view/#perform-a-scroll">
<style>
html {
  height: 10000px;
}
body {
  margin: 0px;
  padding: 0px;
}
#fixed {
  position: fixed;
  bottom: 0px;
  height: 50vh;
  width: 100vw;
  overflow: scroll;
  background-color: gray;
}
input {
  height: 20px;
}
</style>
<div id="fixed">
  <div style="height: calc(80vh - 40px)"></div>
  <input type="text" id="name" />
</div>
<script>
promise_test(async t => {
  assert_equals(window.scrollY, 0);
  assert_equals(visualViewport.scale, 1.0);
  assert_equals(visualViewport.pageTop, 0);

  // Pinch zoom in this document.
  await pinch_zoom_action();

  assert_greater_than(visualViewport.scale, 1.0);

  // Scroll the root scroll container.
  window.scrollTo(0, 1000);
  assert_equals(window.scrollY, 1000);

  const expectedPageTop = visualViewport.pageTop;

  // Now trigger a scrollIntoView call to an element inside a position:fixed element.
  scrollPromise =
      new Promise(resolve => visualViewport.addEventListener("scroll", resolve));
  document.querySelector('#name').scrollIntoView({ behavior: "instant" });
  await scrollPromise;

  assert_greater_than(visualViewport.pageTop, expectedPageTop);
}, "Element.scrollIntoView scrolls visually to a position: fixed element with non-zero layout scroll offset");
</script>