Ajax technology can provide highly interactive web applications and give users a richer page browsing experience. This book focuses on Ajax and related tools and technologies. The main content includes the XMLHttpRequest object and its properties and methods, sending requests and processing responses, building complete Ajax development tools, using JsUnit to test JavaScript, analyzing JavaScript debugging tools and technologies, and Ajax Development models and frameworks, etc. The code for all examples in this book can be obtained for free from the source code (Source Code) on the homepage of this book on the Apress website. This book is suitable for web application developers and web designers at all levels to read.