AJAX

Ajax is a group of interrelated web development methods used on the client-side to create interactive web applications. With Ajax, web applications can send data to, and retrieve data from, a server asynchronously (in the background) without interfering with the display and behavior of the existing page. Data is usually retrieved using the XMLHttpRequest object.

The main purpose of using AJAX is to enable web applications to extract data from various servers in an asynchronous manner; means that the web applications retrieve information from the server in the background without requiring the user to refresh the web page. How is data is retrieved is the basic question that most of the learners ask; this data is retrieved, asynchronously, by using the XMLHttpRequest Object or by using any Remote Scripting methods.

AJAX is basically based on the following web standards

. XML

. HTML

. JavaScript

. CSS

Ajax uses a combination of HTML and CSS to mark up and style information. The DOM is accessed with JavaScript to dynamically display, and to allow the user to interact with the information presented. JavaScript and the XMLHttpRequest object provide a method for exchanging data asynchronously between browser and server to avoid full page reloads.

However, there have been a number of developments in the technologies used in an Ajax application, and the definition of the term Ajax. In particular, it has been noted that JavaScript is not the only client-side scripting language that can be used for implementing an Ajax application; other languages such as VBScript are also capable of the required functionality. JavaScript is the most popular language for Ajax programming due to its inclusion in and compatibility with the majority of modern web browsers. Also, XML is not required for data interchange and therefore XSLT is not required for the manipulation of data. JavaScript Object Notation (JSON) is often used as an alternative format for data interchange, although other formats such as preformatted HTML or plain text can also be used.