Query on the DOM tree

Does anybody know any good way to query on the DOM tree?

If the query is simple with one comparison(for example, if we look for
attribute "first name"="Judy", we can just traverse the tree and compare it
with each note attribute. But I think this way is too simple to overcome the
performance issue. And I don't think it can handle more complicated query.

DOM is claimed is easy to search. But from the API I saw, I did not discover
this feature. Do I miss something? I think this is very basic question. It
must have answer somewhere.


Any advise is highly appreciated.



Angela