This whole tutorial is also available in PDF.
0. Introduction
This tutorial assumes that you have the basic knowledge of HTML, JavaScript and the basis of the client-server model. That is all you need to start building basic AJAX applications.
What is AJAX?
Just for your information, AJAX stands for Asynchronous JavaScript And XML. But don't pay much attention to the name; it is unfortunately chosen. What you need to know is that AJAX is not a new technology, it is a combination of existing technologies like HTML, JavaScript, DHTML and DOM. Really it's just an innovative approach to combine these technologies to suit the needs of the always developing web applications.
What can AJAX do for you?
AJAX can make your webapps more user friendly. Perhaps the easiest illustration is when a user is filling some king of form as a part of your webapp and based on the partial user input you can perform a database check transparently to the user while he is still busy with filling the rest of the form. As a result of that asynchronous request you can assist the user with various information(like username is taken, auto fill the rest of the form...) making the GUI of the webapp user-friendly like the one of a standard stand-alone application.
Mixing the Technologies
Here are the basic technologies involved in AJAX:
- HTML is used to build web forms and identify fields that you'll use in the rest of the webapp
- JavaScript code is the code used in AJAX to facilitate communication with server applications
- DHTML, of Dynamic HTML, helps you update your forms dynamically through usage of div, span and other dynamic HTML elements
- DOM, the Document Object Model, is used to work with both the structure of your HTML and (in some cases) the XML returned from the server.
If so, proceed to the next page where we'll take a look at the XMLHttpRequest object and write some quick AJAX code!
To the next page==>