Page 1 of
6 Next >>
This tutorial covers the basics of AJAX. Before reading this
You may want to read my XML and
XHTML tutorials first.
AJAX stands for Asynchronous
AJAX is a type of programming used to provide better and faster web
applications. It is not a new technology but is based on existing XML and
Because AJAX is based on existing, established technologies, it is supported by
all major browsers including Internet Explorer, Opera, FireFox, etc. Also,
AJAX applications are not dependent on specific web server software. Thus, AJAX
applications are browser and server independent!
Typically, in a web page to get data from a database or server based file, or to
send data to the server, the web page has to contain an HTML
Form. When a user clicks a command button on the page to
get data from the server or to send data to the server, a
Post or Get command is issued to the
web server. The server then responds by performing the requested action,
re-creates the entire page and sends it back to the browser in its entirety.
All this is done while the user waits. This incurs a performance hit and, even
in the best case, the user sees his web page flash as it gets rendered on the
to the web server in an asynchronous manner. It
This object is not a W3C (World Wide
Web Consortium) standard, however, most browsers have implemented it.
using HTTP requests. With an HTTP request the web
page can make a request to, and get a response from, the server without
reloading the entire page!
As a result, only a small amount of data is being exchanged. Because this is
done asynchronously in the background, the user remains on the page and this
happens transparently to him after the page has initially loaded.
AJAX the increases the responsiveness of web pages.
It reduces network traffic on the web server because there will be no post back
to the server so the server doesn't need to render a complete HTML page.
AJAX typically breaks the browser's Back button. When a page is updated
dynamically, returning to the previous page may not be possible. Browsers
usually record only complete page requests in their history lists.
Not all browsers fully comply with W3C standards so an AJAX application must be
tested under all browsers.
Page 1 of
6 Next >>