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Thursday, December 24, 2009

About Ajax

Developing a web application has now been a cup of coffee for developers having knowledge of Ajax technology that was not so easy and hence not popular earlier.

Ajax plays a major role in developing fast, interactive, dynamic and responsive site and can run on various operating systems, computer architectures and browsers.Its asynchronous characteristics have made it popular among the users to develop their site using ajax.

Ajax is not a single technology but an amalgamation of several technologies that ius being used to develop interactive web applications.It is some time referred to asynchronous javascript with added XML, which is used to enhance the interactivity, speed, functionality and usuability of the web pages.

The term Asynchronous refers to functionality of the data processing in which the user can perform the other request without interfering the backend processing and the desired output displays after ending the page-loading process

In short, we can define Ajax as an asynchronous powerful technique that integrates
  • Standards based presentation using XHTML & CSS
  • Data interchange with XML and XSLT
  • Dynamic display and interaction of pages using via DOM
Advantages of Ajax
       The biggest advantage of ajax is its bandwidth usage because it generates HTML  locally within the browser and does not require loding the whole data after amending any portion of the programming.
       The other foremost advantage is that its supports  a wide range of operating system platform, computer architecture, browser and languages.

Disadvantages of Ajax
       Despite of having several advantages, Ajax also has some common disadvantages and some of them are:
  • Though Ajax is a cross platform tool, yet it has limitation, as it cannot run on the old version of Opera and Safari browser and needs to enable XMLHttpRequest to run Ajax
  • Ajax generates dynamic pages that do not register itself with cookies, so user can't find previous pages by pressing 'Back' button, but can enable with GET HTTP request. Cookies also don't work with large request and hence need to add the cookie request.
  • In the absence of proper sitemap, it was difficult for the Search Engine Optimizer to search the web page as  search engine too feel difficulty to execute it, while if it is provided data with full-page refresh.


    1. The first part of the article is decent, but the Advantages and Disadvantages are total nonsense.

      The XML you get over the wire when using AJAX is not necessarily going to be THAT much more concise -- it's just you're loading only enough data to load a portion of the page that's changing. That could still be a large chunk of the page.

      Disadvantages of AJAX -- no, it doesn't run on stone age versions of very minority browsers, but who cares? That's like, 3% of 5% of browsers. Very small.

      Back buttons issues have /nothing/ to do with cookies.

      If you're using AJAX incorrectly (that is, not providing a non-javascript fallback), then yes, parts of your website will be inaccessible to bots, and to some users.

    2. Thanks for valuable comments Maximus