AJAX Tutorial

AJAX stands for Asynchronous JavaScript And XML.

AJAX is a type of programming made popular in 2005 by Google (with Google Suggest).

AJAX is not a new programming language, but a new way to use existing standards.

With AJAX you can create better, faster, and more user-friendly web applications.

AJAX = Asynchronous JavaScript and XML

AJAX is not a new programming language, but a technique for creating better, faster, and more interactive web applications.

With AJAX, your JavaScript can communicate directly with the server, using the JavaScript XMLHttpRequest object. With this object, your JavaScript can trade data with a web server, without reloading the page.

AJAX uses asynchronous data transfer (HTTP requests) between the browser and the web server, allowing web pages to request small bits of information from the server instead of whole pages.

The AJAX technique makes Internet applications smaller, faster and more user-friendly.

AJAX is a browser technology independent of web server software.

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AJAX is Based on Web Standards

AJAX is based on the following web standards:

• JavaScript
• XML
• HTML
• CSS

The web standards used in AJAX are well defined, and supported by all major browsers. AJAX applications are browser and platform independent.

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AJAX is About Better Internet Applications

Web applications have many benefits over desktop applications; they can reach a larger audience, they are easier to install and support, and easier to develop.

However, Internet applications are not always as "rich" and user-friendly as traditional desktop applications.

With AJAX, Internet applications can be made richer and more user-friendly.

AJAX can be used for interactive communication with a database.

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AJAX Database Example

In the AJAX example below we will demonstrate how a web page can fetch information from a database using AJAX

As you can see it is just a simple HTML form with a drop down box called "customers".

The paragraph below the form contains a div called "txtHint". The div is used as a placeholder for info retrieved from the web server.

When the user selects data, a function called "showCustomer()" is executed. The execution of the function is triggered by the "onchange" event. In other words: Each time the user change the value in the drop down box, the function showCustomer is called.