third_party/web_platform_tests/dom/nodes/Element-getElementsByClassName.html

<!DOCTYPE html>
<title>Element.getElementsByClassName</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<div id="log"></div>
<script>
test(function() {
  var a = document.createElement("a"), b = document.createElement("b")
  b.className = "foo"
  a.appendChild(b)
  var list = a.getElementsByClassName("foo")
  assert_array_equals(list, [b])
  var secondList = a.getElementsByClassName("foo")
  assert_true(list === secondList || list !== secondList, "Caching is allowed.")
}, "getElementsByClassName should work on disconnected subtrees.")
test(function() {
  var list = document.getElementsByClassName("foo")
  assert_false(list instanceof NodeList, "NodeList")
  assert_true(list instanceof HTMLCollection, "HTMLCollection")
}, "Interface should be correct.")
</script>