I just mentioned the sale O'Reilly is having on HTML5 Books, and it turns out they are also having a sale on JavaScript Books.
Some really, really good books on JavaScript. I own and have read most of them and consult a lot of them on a daily basis for the various JavaScript Patterns and Practices.
I have written a few book reviews on some of them, but many of them I have not.
I would do some googling as to ones people recommend. I personally read a lot and have enjoyed most of them.
Check out the O'Reilly sale on JavaScript books.