ASP.NET AJAX Interview Questions and Answers (61) - Page 1

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What is AJAX

AJAX = Asynchronous JavaScript and XML

AJAX is not a new programming language, but a new technique for creating better, faster, and more interactive web applications.

With AJAX, a JavaScript can communicate directly with the server, with the XMLHttpRequest object. With this object, a JavaScript can trade data with a web server, without reloading the page.

AJAX uses asynchronous data transfer (HTTP requests) between the browser and the web server, allowing web pages to request small bits of information from the server instead of whole pages.

The AJAX technique makes Internet applications smaller, faster and more user-friendly.

AJAX applications are

NOTE: This is objective type question, Please click question title for correct answer.

Can you nest UpdatePanel within each other?

NOTE: This is objective type question, Please click question title for correct answer.

Which property needs to be set for script manager control to extend the time before throwing time out expection if no response is received from the server?

AsyncPostBackTimeout Property needs to set which gets or sets a value that indicates the time, in seconds, before asynchronous postback time out if no response is received from the server.

 <asp:scriptmanager id="scriptManager1" runat="server" asyncpostbackerrormessage="We can not serve your request at this moment.Please try later." asyncpostbacktimeout="36000"></asp:scriptmanager>

The default value of this property is 90 second. We can also set the user defined error message using asyncpostbackerrormessage property (as shown in above code) for time out.

AJAX applications are

NOTE: This is objective type question, Please click question title for correct answer.

Is it possible to use FileUpload control within the update panel?

Yes, it's possible. But we need to use Postback triggers to upload the file.

Is it compulsory to have Script manager on the page when you are using any control of ajax control tool kit?

Yes. Page needs to have a script manager for ajax control tool kit controls to work.

Which control you need to place on the page to show loading image?

NOTE: This is objective type question, Please click question title for correct answer.

What is the DisplayAfter property in UpdateProgress control?

Displayafter property specifies after how many seconds the loading image needs to be displayed in ajax postback. It takes values in seconds.

How many types of triggers are there in update panel?

There are 2 types of triggers.
1. PostBackTrigger : It does a full postback. This is useful when any such control which placed within updatePanel but it cannot work asynchronously. Like File Upload Control.
2. AsyncPostBackTrigger :- It does partial post back asynchronously.

If there are multiple update panels on the page say Upd1 and Upd2. There is a button placed in Upd1. How can you stop Upd2 to update when button placed in upd1 is clicked?

There is a property called UpdateMode which takes two values
1.Always : Default value of this property.
2.Conditional

When set to conditional, then that updatepanel's content only gets updated when control placed in that update panel does a postback. Control placed in other update panel will not affect this updatepanel.

Tell name of all the control of Ajax?

There are 5 controls.
1. ScriptManager
2. UpdatePanel
3. UpdateProgress
4. Timer
5. ScriptManageProxy

What will happen with click of browser “back” button among asynchronous requests?

By default, browser will unload the web page and and will return to previous Web page, independent of any asynchronous requests.

This attribute of scriptmanager is useful to implement browser history management,

NOTE: This is objective type question, Please click question title for correct answer.

Default value of EnableHistory attribute in scriptmanager is,

NOTE: This is objective type question, Please click question title for correct answer.

To create browser history point using client script, we make call method…

NOTE: This is objective type question, Please click question title for correct answer.

What is AjaxControl ToolKit?

AjaxControl Toolkit is an open source project built on top of ajax framework. It has more than 30 controls which are really cool and useful.

Visit this site to find out more about AjaxControlToolKit.

http://www.asp.net/(S(fu2l2uzphr2u3u45q2dnez55))/ajax/AjaxControlToolkit/Samples/