AJAX stands for Asynchronous JavaScript and XML. AJAX is fundamentally DHML (JavaScript and HTML) combined with XML technologies to produce fancier interfaces. The difference between an AJAX web page and a regular HTML page is basically this: A regular HTML page loads once, every time a user clicks a link or a button the page reloads and refreshes. AJAX basically points to the section of the web page that needs to be changed and then allows the page to appear to have actually changed by changing the appearance or moving the object in the client side, while storing the information on the back end and updating the information in a manner which is more smooth than traditional page refreshing.

 

The use of AJAX on a page has its own set of tradeoffs. With AJAX you have better control over the document itself and the information that is passed from the client to server is greatly reduced. Along with this seamless interface changing behavior, AJAX removes the annoying page reloads that regular HTML interfaces incorporate. On the other hand though, an AJAX application is a lot more complicated than a traditional interface, with the increased complexity means that there is much greater risk for browser incompatibilities and code problems. Most developers want to make their applications available to the greatest amount of users, knowing the different technologies that are available and what the pros and cons of using those technologies is an advantage in this field.

 

One of the drawbacks of using AJAX in an application is that the AJAX application may break the behavior of the back button. This is caused because the use of the back button, to the browser, is returning to a previous static page, with an AJAX application this may not be available and so the back button appears to be broken. Users expect that a back button will return them to a previously loaded page. So the expectations of the back button differ between the client software (the browser) and the user (your customer), which can cause usability problems.

 

There are ways around the functionality of the back button, such as use of an iFrame that invokes the changes that populate the browsers history button. This technique is used by companies such as Google, in their Google Maps application.

 

Another issue with AJAX applications is that dynamic web pages often are difficult for users to bookmark particular pages inside an application that carries state. The user will expect that they can bookmark the page and then return to it at any time, but the carrying of session state will deny the user access into the page at a later time. Of course there are solutions for his problem as well, such as is the use of bookmarks inside the application so that the user can return to the application at any given state within it. This process allows this behavior as long as JavaScript is enabled on the client (the users' browser). Although this solution may work, it is not necessarily deemed to be a fix for the problem, it can however, get your application around some of the drawbacks of AJAX.