HTML, XHTML, & CSS All-in-One For Dummies®, 2nd Edition

Chapter 1. AJAX Essentials

In This Chapter

• Understanding AJAX

• Using JavaScript to manage HTTP requests

• Creating an XMLHttpRequest object

• Building a synchronous AJAX request

• Retrieving data from an AJAX request

• Managing asynchronous AJAX requests

If you've been following the Web trends, you've no doubt heard of AJAX. This technology has generated a lot of interest. Depending on who you listen to, it's either going to change the Internet or it's a lot of overblown hype. In this chapter, I show you what AJAX really is, how to use it, and how to use a particular AJAX library to supercharge your Web pages.

The first thing is to figure out exactly what AJAX is and what it isn't. It isn't:

• A programming language: It isn't one more language to learn along with the many others you encounter.

• New: Most of the technology used in AJAX isn't really all that new; it's the way the technology is being used that's different.

• Remarkably different: For the most part, AJAX is about the same things you'll see in the rest of this book: building compliant Web pages that interact with the user.

So you have to be wondering why people are so excited about AJAX. It's a relatively simple thing, but it has the potential to change the way people think about Internet development. Here's what it really is:

• Direct control of client-server communication: Rather than the automatic communication between client and server that happens with Web forms and server-side programs, AJAX is about managing this relationship more directly. ...