While taking this API apart to implement in javascript (as exercise to learn how to read specs) I noticed that methods like firstChild() and lastChild() are stuck on the root node when implementing the specification.

For example:
> tw = document.createTreeWalker(document.body, NodeFilter.SHOW_ALL).firstChild()

In Chrome this returns document.body.firstChild.

However when following the spec:

| document.createTreeWalker( Node root, .. )
| * http://dom.spec.whatwg.org/#dom-document-createtreewalker
| > currentNode = root
| TreeWalker::firstChild()
| * http://dom.spec.whatwg.org/#concept-traverse-children
| > node = current = tw.currentNode
| - Filter
| - * http://dom.spec.whatwg.org/#concept-node-filter
| - > node's nodeType is accepted through NodeFilter.SHOW_ALL
| > tw.currentNode = node; // unaltered
| > return node;

Unless it was intended this way, I appears the spec is missing something in either the Filter or the "Traverse children" subsets to get it off the root.


PS: I've looked at all three of these but since I noticed no significant differences in this regard I've only linked to the last one above
* http://www.w3.org/TR/2012/WD-dom-20120105/#interface-treewalker
* http://www.w3.org/TR/dom/#interface-treewalker
* http://dom.spec.whatwg.org/#interface-treewalker