traverse .xml using js

Hi, I'm just learning javascript in association with its handling .xml files.
I already know how to open a simple .xml file in js and show an element of it (with the alert command). I want to make a js program that opens any .xml file, and shows (using alert()) all its elements. Since what i want is to "visit all the nodes in tree" I've found some algorithms on the net but i cannot put them to practice because all use queue, and I do not know how to do them in js.

Any help will do! Thanx in advance.