"Ajax in Action" is not only an excellent book on Ajax, but the best JavaScript book I have ever read. The authors note early on that Ajax is a process, not a technology. This theme permeates the book. There is an emphasis on requirements, design, implementation, testing and maintenance. So the book shows how to do a real project, not just how to code.

Keeping with the real project theme, there is information throughout on refactoring and design patterns. The authors present low level coding idioms as well. All this creates a language for coding Ajax applications. The second half of the book walks you through the entire development process for five sample applications.

The book targets a wide audience range, from enterprise developers to self-taught scripters. Basic concepts are explained concisely for newcomers and experienced developers may skim certain sections. However these sections are a very small part of the 600+ page book.

An appendix covers an introduction to JavaScript. While you would want to supplement it with materials from the web, it clearly covers the advanced topics that are hard to find elsewhere. There are also introductions and tips on CSS and DOM. In short, I learned a ton about non-Ajax development and page manipulations too.

And the book even has a screenshot of JavaRanch! I was expecting a good book when I saw Bear and Ernest's comments on the back. But it still managed to exceed my expectations!