first-child-last-child.html

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This WPT test may be referenced by the following Test IDs:
- /css/selectors/invalidation/first-child-last-child.html - WPT Dashboard Interop Dashboard

<!DOCTYPE html>

<html>

  <head>

    <meta charset="utf-8">

    <title>CSS Selectors Invalidation: :first-child :last-child</title>

    <link rel="help" href="https://drafts.csswg.org/selectors-4/#the-first-child-pseudo">

    <meta name="assert" content="This tests that the :first-child and :last-child selectors are effective">

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

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

    <style>

      div {

        color: black;

      span:first-child {

        color: blue;

      span:last-child {

        color: red;

    </style>

  </head>

  <body>

    <div id="target"><span>first-initially</span><span>last-initially</span></div>

    <script>

'use strict';

const black = 'rgb(0, 0, 0)';

const blue = 'rgb(0, 0, 255)';

const red = 'rgb(255, 0, 0)';

test(() => {

  const target = document.querySelector('#target');

  const first = target.firstChild;

  assert_equals(getComputedStyle(first).color, blue);

  target.insertAdjacentHTML('afterbegin', '\n<span>foo</span><span>bar</span>');

  assert_equals(getComputedStyle(target.firstElementChild).color, blue);

  assert_equals(getComputedStyle(first).color, black);

  while (target.firstElementChild !== first)

    target.removeChild(target.firstElementChild);

  assert_equals(getComputedStyle(first).color, blue);

}, 'Adding multiple nodes at once should invalidate :first-child correctly.');

test(() => {

  const target = document.querySelector('#target');

  const last = target.lastChild;

  assert_equals(getComputedStyle(last).color, red);

  target.insertAdjacentHTML('beforeend', '\n<span>foo</span><span>bar</span>');

  assert_equals(getComputedStyle(target.lastChild).color, red);

  assert_equals(getComputedStyle(last).color, black);

  while (target.lastChild !== last)

    target.removeChild(target.lastChild);

  assert_equals(getComputedStyle(last).color, red);

}, 'Adding multiple nodes at once should invalidate :last-child correctly.');

    </script>

  </body>

</html>