I would strongly advise you to take no notice of the javascript standard, and to entirely ignore deprications. (unless you are a browser vendor).
I would really really love, with all my heart to see even just one vendor (I use Opera, and even that isnt perfect) to actually make an effort to implement the standard.
You really need to test each and every javascript function you intend to use, accross browsers (versions as well as vendors) yourself, as support is abritrary and bad.
This is an absolute nightmare, as you will find the same function to work *differently* on different systems, this is one of the main reasons why
you should try to do as much as possible on the server (
JSP servlets etc.).
James