21.How can you find out that an AJAX request has been completed?

ReadyState property is used to check whether AJAX request has been completed. If the property is equal to four, then the request has been completed and data is available.

22.Is javascript knowledge is required to do Ajax?

Yes, if you plan to develop new AJAX functionality for your web application.

23.What are all the browsers support AJAX?

Following browsers support AJAX:

• Internet Explorer 5.0 and above
• Opera 7.6 and above
• Netscape 7.1 and above
• Safari 1.2 and above

24.How can you test the Ajax code?

JSUnit is the client side javascript code used as part of JUnit. JSUnit has been used for Ajax code.

25.Is Ajax said to be a technology platform or is it an architectural style?

Ajax supports both technology and as architectural style.

26.How can AJAX applications be debugged?

Two tools are used for debugging:

• Fiddler for IE
• Firebug for Mozilla.

27.How can we cancel the XMLHttpRequest in AJAX?

Abort() method can be called to cancel the XMLHttpRequest in Ajax.

28.. Is AJAX code cross browser compatible?

No, it is supporting cross browser compatible. If the browsers supports native XMLHttpRequest JavaScript object, then this can be used.

29.What is the name of object used for AJAX request?

XmlHttpRequest object is used for Ajax requests.

30.What is prerequisite for Update Panel in Ajax?

Script Manager is pre-requisite to use Update Panel controls.

31. How many update panel can be used per page?

There are no restrictions on the number of update panels per page.

32.What is Script Manager?

Script Manager helps manage the client side script of AJAX. Script Manager acts as a mediator as AJAX depends on JavaScript. Every page that uses AJAX has a Script Manager to enable AJAX libraries.

33.How Ajax objects can be created?

Following syntax can be used to create Ajax objects:
Var sample = New ajaxObject(‘path of the page’)

34.What are the protocols used by Ajax?

• HTTP’s GET or POST
• XMLHttpRequest for placing a request with the web server
• Uses JSON to communicate between the client and server
• UED or URL encoded data

35.What are all the security issues of Ajax?

Security issues that can be encountered

• When Ajax calls are sent through plain text and it may lead to know the database details
• Inserting scripts can also be possible and attackers can easily penetrate into the system

36.How can we handle concurrent requests?

Javascript functions should be written to handle concurrent requests and call back function can be passed as a parameter. Those parameters are passed to AjaxInteraction(URL, callback) object.

37.Define the role of the Update Panel?

Update Panel is used to add functionality to the existing ASP.NET applications. By using partial page rendering, it can be used to update the content. Refresh can be made for the partial page instead of whole page.

38.Can we use nested update panel in Ajax?

Yes, we can use nested update panel in Ajax. Update panels can be nested to have more control over the Page Refresh.

39.What are the types of post back in Ajax?

There are two types of post backs:

• Synchronous Postback
• Asynchronous Postback

40.How can we handle exception handling in Ajax?

ErrorTemplate which is the child tag of Script Manager is used to handle exception handling in Ajax.