My reference for this kind of stuff is <a href="http://w3schools.com" rel="nofollow">http://w3schools.com</a> , a bit light on examples, but a good reference if you just need to know the syntax.
I would start with the Rhino book<p><a href="http://www.amazon.com/JavaScript-Definitive-Guide-David-Flanagan/dp/0596101996/ref=sr_1_1?ie=UTF8&s=books&qid=1214480859&sr=1-1" rel="nofollow">http://www.amazon.com/JavaScript-Definitive-Guide-David-Flan...</a>
It is embarrassing to have to admit that I'm only halfway through a book as compact as <i>JavaScript: The Good Parts</i>. But so far it is a very good book.<p><a href="http://www.amazon.com/JavaScript-Good-Parts-Douglas-Crockford/dp/0596517742/ref=pd_bbs_sr_1?ie=UTF8&s=books&qid=1214513018&sr=8-1" rel="nofollow">http://www.amazon.com/JavaScript-Good-Parts-Douglas-Crockfor...</a>
There's a veritable wealth of info over at <a href="http://developer.yahoo.com/" rel="nofollow">http://developer.yahoo.com/</a><p>The Web Developers Handbook is also pretty useful <a href="http://www.alvit.de/handbook/index.php" rel="nofollow">http://www.alvit.de/handbook/index.php</a>
QuirksMode offers a lot of help, especially on tricky cross browser issues.
<a href="http://www.quirksmode.org/js/contents.html" rel="nofollow">http://www.quirksmode.org/js/contents.html</a>