This book is aimed at experienced ASP.NET developers looking to add AJAX to their applications, and experienced web developers looking to move to ASP.NET and AJAX together.
In this book, I assume that you already have an understanding of how ASP.NET works. For an in-depth discussion of ASP.NET, I recommend Professional ASP.NET 2.0, by Bill Evjen, et al. (Wrox, 2005). The focus here is on how you can extend ASP.NET applications to update portions of the page asynchronously and to add richer UI elements to a page. ASP.NET AJAX makes it easy to enrich your existing application or to design a new application to provide a better experience for users. The differences among modern browsers have been abstracted, allowing you to write to a common set of APIs and trust that the user will get the correct behavior whether they are using Internet Explorer, Firefox, or Safari.
If you know how to author ASP.NET pages, you can easily start using the Microsoft AJAX library to manipulate the browser’s Document Object Model and communicate with the server to update the user’s view of data without forcing them to wait for the entire page to be refreshed.