The term, coined by Jesse James Garrett of Adaptive
Path, actually came about fairly recently (in 2005). Garrett (and probably others within Adaptive
Path) came up with the termas a convenient way of describing a specific interaction:
Asynchronous JavaScript and XML.
With Ajax, JavaScript can communicate with the server, returning results in a chunk of
XML. You can then use that new data to update what the user sees on the screen, and it all is
done without a page refresh. The great thing about this process is the asynchronous part: you
can perform these tasks behind the scenes while the user continues to interact with the page
at hand.
This chapter covers the following:
??? Deconstructing the Ajax process
??? Understanding data formats
??? Building a reusable Ajax object
??? Using libraries to handle Ajax calls
First, however, let??™s look at a good example of Ajax and how it achieves the effects it does.
Examining an Ajax Application
Google Docs & Spreadsheets??”along with most of the Google online applications, for that
matter??”demonstrates the power of Ajax very well (see Figure 5-1). Changes to your document
get constantly sent back to the server to be saved. This type of interaction is just like
using a desktop application such as Microsoft Word. And although many of the applications
that make use of the technique attempt to be like desktop applications, it can be used for
even small tasks that can make a site seem extremely responsive and fun to use.
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