It's been a very very long time since I've done any heavy commercal JavaScript! I've decided that it's about time I got back into and brought myself up to speed.

I would like to get a book on it, preferably a SitePoint book, which would be best? or

Or can anyone else recommend a book? I'm not looking for a beginner book, I've got 2 years extensive experience with JS, just mainly need a refresher and something that covers over whats changed in the past 4-5 years