Java Reference
In-Depth Information
14
Ajax
What You Will learn in this Chapter:
➤
Making HTTP requests with the
XMLHttpRequest
object
➤
Writing a custom Ajax module
➤
Working with older Ajax techniques to preserve usability
Wrox.Com Code doWnloads for this Chapter
You can find the wrox.com code downloads for this chapter at
http://www.wiley.com/go/
BeginningJavaScript5E
on the Download Code tab. You can also view all of the examples
Since its inception, the Internet has used a transaction‐like communication model; a browser
sends a request to a server, which sends a response back to the browser, which (re)loads the
page. This is typical HTTP communication, and it was designed to be this way. But this model
is rather cumbersome for developers, because it requires web applications to consist of several
pages. The resulting user experience becomes disjointed and interrupted due to these separate
page loads.
In the early 2000s, a movement began to look for and develop new techniques to enhance the
user's experience; to make web applications behave more like conventional applications. These
new techniques offered the performance and usability usually associated with conventional
desktop applications. It wasn't long before developers began to refine these processes to offer
richer functionality to the user.
At the heart of this movement was one language: JavaScript, and its ability to make HTTP
requests transparent to the user.
