Links
The Javascript tutorials at w3schools.com are a rich and reliable source of information about the language.
You can find bugs and stylistic issues in your Javascript programs by running them through Douglas Crockford's online JSLint utility. Many subtle problems with the Perlenspiel engine were discovered with this handy tool. I recommend checking the “tolerate messy white space” option, or you'll go crazy. We cannot all be saints.
If you're using Aptana Studio to develop your games, you can link JSLint directly into Aptana's editor so that it catches problems as you type. This is an enormous time-saver. Google APTANA JSLINT for instructions.
The most useful printed reference to the Javascript language is “the Rhino Book,” David Flanagan's Javascript: The Definitive Guide (6th Edition; O’Reilly, 2011, ISBN 0596805527).
Another useful book is Douglas Crockford's Javascript: The Good Parts (O'Reilly/Yahoo Press, 2008; ISBN 0596517742). It's entertainingly written, and filled with excellent advice for writing Javascript that takes advantage of the language's strengths while avoiding its many weaknesses. I strongly urge you to read this short book from cover to cover before diving into Javascript.
If you are seriously interested in the creative aspects of game design, I recommend Jesse Schell's The Art of Game Design: A Book of Lenses (Morgan Kaufman, 2008, ISBN 0123694965).