jQuery in Action, First Edition is written by Bear Bibeault and Yehuda Katz and is probably the simplest and easiest to understand programming book available. Target reader is somebody that already is using javascript in projects and is looking to push the limits of their web applications by using jQuery and many of it’s great plugins.
I found the book and its appendices to be extremely well written. I found the examples to be superbly written and extremely usable in my projects: there aren’t a lot of examples on basic things like selectors but there are a ton of great examples on much more advanced concepts. An additional feature that I found really helpful was the interactive lab exercises that begin around chapter two.
As a reference, which I don’t think was the primary intent, it would be difficult to use the book as some of the API is randomly spread throughout the book. The random spread does make the book a lot better though, because each chapter definitely builds well upon the previous chapter.
I completely recommend this book and can only imagine that the Second Edition improves upon the First Edition. I haven’t really found much negative about the book other than wishing the API wasn’t spread out so much, but the index is very good.