Advantages and Disadvantages of AJAX

Advantages:

1. XMLHttpRequest - It is used for making requests to the non-Ajax pages. It supports all kind of HTTP request type.
 

2. IFrame  - It can make requests using both POST and GET methods. It supports every  modern browsers. It  supports asynchronous file uploads
   
3. Cookies - In spite of  implementation difference among browsers it supports large number of browsers
4. The interface is much responsive, instead of the whole page, a section of the page is transferred at a time.
5. Waiting time is reduced
6. Traffic to and from the server is reduced.
   

Disadvantages:

1. XMLHttpRequest -In the older version of IE (5 & 6) ActiveX to be enabled, this feature is available in new browsers and latest version of few. 
   
2. IFrame - Requests have to be asynchronous. The design of the Server pages must be compatible with IFrame requests  There is an implementation difference among different   browsers. Unnecessary history records can be left on the history record of the browser. Request size is increased due to the fact that data is URL-encoded.
   
3. Cookies - It prohibits no synchronous requests, it does not cope with large 
   requests/results The server pages requires to be designed to work with cookie requests.