jsdom is currently missing the document traversal interfaces NodeIterator, NodeFilter, and TreeWalker. These aren't part of the core spec but their absence makes it more difficult to write efficient code that runs on both the client and the server.
Is there any spec in which they are present? jsdom is an implementation of the "W3C DOM," so if there's no W3C spec for it, it's out of scope. But if there's e.g. a DOM Traversal spec, then this is definitely a missing feature.
Oh, whoops, I found it: DOM Level 2 Traversal and Range.
Derbyjs currently uses TreeWalkers in their front-end code. I’ll probably try to implement them soon.
btw, this is a duplicate of #317; I suggest we move to that one.