"Everything from asynchronous requests using the XMLHttpRequest object and JSON data exchange, through state-of-the-art Ajax frameworks and offline Ajax techniques. You’ll discover practical solutions for Ajax debugging, security, and usability. You will also learn how to apply Test-Driven Development techniques to your Ajax development projects."

Here's what the breakdown of the lessons:

-JavaScript Basics
-Ajax Debugging (covers FireBug etc...)
-The XMLHttpRequest Object and Data
-Introduction to Ajax Frameworks
-Test-Driven Ajax Development
-Offline Ajax
-Ajax Security
-Ajax Usability
-Ajax User Interface Patterns

Watch the chapter on the XML HTTP Request Object.

Or download it here from InformIT.