Using the DocumentFragment Interface

Hi all

I have a requirement to find out how many times an Element of a
particular name  occurs in a subtree of document below a Node n. The
approach which I believe I should take is:

- create a subtree whose root is at n
- employ the getElementsByTagName(name) method to generate an
appropriate NodeList

To create subtrees, there is the DocumentFragment interface. And here is
my problem: I don't know how to use any of the methods to create a
documentFragment beneath a given Node (I'm not a programming vet', you
see). Is this the correct approach to take?

The alternative I see is a little more complex:

- determine all the child Nodes of Node n, by applying the
getChildNodes() method in breadth-first manner on all element nodes at
and beneath n.
- manually pick out those nodes with a particular nodeName.

I believe the Element interface approach to be the more elegant...Any
advice on how I can realise it would be cool.

Regards

Nigel

PS Just trawled through the archives and couldn't find the answer...:-(