third_party/web_platform_tests/dom/nodes/Node-childNodes.html

<!DOCTYPE html>
<meta charset=utf-8>
<title>Node.childNodes</title>
<link rel=help href="https://dom.spec.whatwg.org/#dom-node-childnodes">
<link rel=author title="Tim Taubert" href="mailto:ttaubert@mozilla.com">
<link rel=author title="Ms2ger" href="mailto:Ms2ger@gmail.com">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<div id="log"></div>
<script>
test(function() {
  var element = document.createElement("p");
  assert_equals(element.childNodes, element.childNodes);
}, "Caching of Node.childNodes");

var check_parent_node = function(node) {
  assert_array_equals(node.childNodes, []);

  var children = node.childNodes;
  var child = document.createElement("p");
  node.appendChild(child);
  assert_equals(node.childNodes, children);
  assert_array_equals(children, [child]);
  assert_equals(children.item(0), child);

  var child2 = document.createComment("comment");
  node.appendChild(child2);
  assert_array_equals(children, [child, child2]);
  assert_equals(children.item(0), child);
  assert_equals(children.item(1), child2);

  assert_false(2 in children);
  assert_equals(children[2], undefined);
  assert_equals(children.item(2), null);
};

test(function() {
  check_parent_node(document.createElement("p"));
}, "Node.childNodes on an Element.");

test(function() {
  check_parent_node(document.createDocumentFragment());
}, "Node.childNodes on a DocumentFragment.");

test(function() {
  check_parent_node(new Document());
}, "Node.childNodes on a Document.");
</script>