preventScroll-textarea.html

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This WPT test may be referenced by the following Test IDs:
- /html/interaction/focus/processing-model/preventScroll-textarea.html - WPT Dashboard Interop Dashboard

<!doctype html>

<title>focus(options) - preventScroll on textarea element</title>

<link rel="author" href="https://mozilla.org" title="Mozilla">

<link rel="author" href="mailto:emilio@crisal.io" title="Emilio Cobos Álvarez">

<link rel="help" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1634153">

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

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

<div style="height: 200vh"></div>

<textarea>ABCD</textarea>

<input value="EFGH">

<button></button>

<div style="height: 200vh"></div>

<script>

promise_test(async function(t) {

  await new Promise(resolve => window.addEventListener("load", resolve));

  let elements = document.querySelectorAll("textarea, input, button");

  assert_equals(elements.length, 3, `Precondition`);

  for (let element of elements) {

    let name = element.nodeName;

    assert_equals(window.scrollY, 0, `${name}: Precondition`);

    element.focus({ preventScroll: true });

    assert_equals(window.scrollY, 0, `${name}: Should not have scrolled`);

    assert_equals(document.activeElement, element, `${name}: Should have been focused`);

    // Wait a couple event loop turns because the original bug was triggered off

    // an async event.

    await new Promise(resolve => t.step_timeout(resolve, 0));

    await new Promise(resolve => t.step_timeout(resolve, 0));

    assert_equals(window.scrollY, 0, `${name}: Should not have scrolled after a couple event loop ticks`);

    assert_equals(document.activeElement, element, `${name}: Should remain focused`);

    // Also wait for rendering, just out of paranoia.

    await new Promise(resolve => requestAnimationFrame(resolve));

    await new Promise(resolve => requestAnimationFrame(resolve));

    assert_equals(window.scrollY, 0, `${name}: Should not have scrolled after rendering`);

    assert_equals(document.activeElement, element, `${name}: Should remain focused after rendering`);

}, "preventScroll: true on a textarea element");

</script>