AJAX: Introduction

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AJAX is acronym for Asynchronous JavaScript and XML. AJAX is used to do HTTP requests for a small portion of the web page instead of the whole web page and thus increasing the performance. Your browser needs to be AJAX Compatible for AJAX scripts to work. Most of the latest browsers are AJAX compatible. The popular Ajax compatible browsers are

• Internet Explorer 5.0+
• Firefox 1.0+
• Opera 8+
• Safari 1.2+
  

AJAX is a browser technology and coding is done in JavaScript. AJAX is server technology independent. Any server technology like Servet/JSP, ASP.NET, PHP, Cold Fusion can be used for web requests.

Advantages of AJAX

• AJAX gives your application better look and feel. AJAX takes a web application’s look and feel nearer to desktop application’s look and feel.
• Web pages in AJAX are Asynchronous which means only parts of the page are updated, this makes the response faster compared to the traditional complete page transition method. Best example here is Google suggest.
• Minimal amount of data can be sent and received from the server.

Disadvantages of AJAX

• Back/forward buttons don’t work properly as AJAX requests are not cached in the browser history and only the URL’s in location bar are stored in history
• Bookmaking cannot be done easily for AJAX requests.
• AJAX is presently no compatible for Search Engine Optimization. If your site is content driven and ROI(Return of Investment) is purely visibility of content on search engines the AJAX is not the right choice.
• AJAX does not work if Java Script is disabled.
• AJAX is not compatible in WAP websites as most of the mobile browsers do not support Java Script
  

AJAX is Popular

Nowadays all major websites use AJAX extensively. Some of the popular examples are

• Google suggest where the search box gives you the dropdown menu of the popular searches as soon as you start typing. In fact Google suggest is the most popular AJAX implementation to date and is regarded as an AJAX evangelist.
• GMail
• Yahoo Mail
• BBC
• CNN
• Face Book
• Google Maps

And this list can go on and on, Bottom line is AJAX has now become an essential component in the web programming bouquet.

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