Creating Web Sites Bible, Third Edition

Chapter 17. Ajax

IN THIS CHAPTER

• XMLHttpRequest

• DOM 3 specifications for IDL node

• Interface

• Ajax and Mobile Web

• Ajax quick reference

Ajax is short for "Asynchronous JavaScript and XML." It is cross-platform. It is effectively open source. It is supported by these versions of the major browsers:

• Internet Explorer 5.0 and up

• Netscape 7 and up

• Firefox, Opera 8+

• Safari 1.2 and up

Chapter 13 discussed JavaScript and Chapter 16 discussed XML in detail. Ajax uses JavaScript to encode, call, transmit, and return small packets of data without requiring a screen reload.

Although it would be a stretch to call Ajax a new technology, and it is certainly not a programming language, it is an adaptive implementation of preexisting tools to provide an integrated, efficient new tool that can be used to make better, faster, more versatile Web applications.

As you may know, Ajax, which is a mix or reformulation of existing technologies, facilitates server interaction with elements of a Web page. This, in turn, results in a more responsive application with lower bandwidth usage, and, hence, lower costs, resulting in a win-win situation for all concerned. It is also these features that make it attractive to the so-called Web 2.0 crowd and, those who are involved in software design and development for mobile handheld devices. We will be looking at the future of Ajax in the Mobile Web later this the chapter.

Following are the major components of Ajax:

• JavaScript as the scripting language to call functions

• XMLHttpRequest ...