Beginning JavaScript® and CSS Development with jQuery

Chapter 7. AJAX

AJAX is the technology that encompasses the ability to make arbitrary HTTP requests from JavaScript to obtain new data without the need for reloading a document. AJAX stands for "Asynchronous JavaScript and XML." The name is misleading, though, since you don't have to use XML at all. XML is just one of many possible formats that you can use to transmit data from a server to a client-side JavaScript.

Using AJAX it becomes possible to make web documents behave much less like documents and much more like completely self-contained desktop applications. The advantages of web-based applications have come to be recognized en masse in recent years with the mainstream adoption in ever-greater frequency of AJAX to make seamless, cross-platform, ubiquitously available web-based portals like Google's gmail service and numerous other web-based offerings, or Apple's MobileMe service. With a web-based application, updates are much easier to propagate, since everyone upgrades immediately upon their next visit to the website. No longer do companies have to worry about maintaining legacy software and users — with a web-based application, everyone is pushed to the latest version. It also becomes easier for a user to access these applications. Since a separate installation is not required on every computer where the application's use is desired, all that is required is a capable browser on top of moderately capable hardware. Browsers strive to blur the line between desktop applications ...