01-03-2013, 12:54 PM
Ajax Programming for the Absolute Beginner
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INTRODUCTION
elcome to Ajax Programming for the Absolute Beginner! Ajax (Asynchronous
JavaScript and XML) is a collection of web development technologies that
can be used to create web applications that provide levels of responsiveness
previously unheard of. As a result, when combined with high-speed internet connections,
you can use Ajax to develop web applications that behave and respond
like desktop applications.
In recent years, web developers have begun to make major investments in Ajax,
using it to create a whole new generation of web applications. For example, Google
has used Ajax in the creation of all its latest applications, including Google Suggest,
Google Maps, and Gmail. Amazon.com has used Ajax in the development of
its A9.com search engine as well as to enhance and improve its main website.
Websites like Ask.com and Snap.com have used Ajax to make major improvements
to their search engines. Other companies have used Ajax to help develop entire
office suites of free online applications. For example, ThinkFree Online
(www.thinkfree.com) can create text documents, spreadsheets, and presentations
all of which are 100 percent compatible with Microsoft Office. Google’s Google
Docs Online office suite (docs.google.com) is another example of online applications
developed using Ajax.
WHY AJAX?
Ajax changes the way in which web applications are designed, replacing requests for new web
pages and screen refreshes with small data queries to web servers. By requesting less data,
the web servers are able to respond quicker. Ajax data requests are made asynchronously,
meaning that users no longer have to sit and wait for the web server to fulfill a request.
Instead, the user can continue to work with the web application while Ajax collects and processes
the web server’s data in the background, and when it is time to do so, Ajax can use the
data to dynamically update the web page without forcing a page reload. The end result is a
streamlined, faster, and more desktop-like experience.
Because it relies on commonly available technologies like JavaScript and XML, Ajax is readily
available and supported by all major computer operating systems and web browsers. You do
not have to download and install any special software to work with Ajax, and the people who
visit your website do not have to install anything to view and interact with your Ajax
applications.
INTRODUCTION ON AJAX
Ajax represents a powerful new way of developing web applications. It does
away with the traditional model of breaking down web applications into
multiple pages that must constantly be loaded and reloaded. Instead, Ajax
supports the development of applications that seamlessly update page content,
pulling data from the web server behind the scenes, without requiring any page
reloads. The end result is a faster, more desktop-like end-user experience. This
chapter provides an overview of Ajax and the different technologies that it uses to
provide web developers with the tools needed to create a new generation of powerful,
fast, and responsive applications. This chapter will also provide an overview
of a number of different Ajax applications, offering examples of the kinds of things
that Ajax is capable of performing.