How to make a simple yes/no popup in ASP.NET that return the result back to my c#?

Question

With ASP.NET, how do I prompt the user for a yes/no question and getting the result back to my .ascx?

So far I can open a confirmation dialog with use of Javascript,

Answer 1

This is not a good practice to do this. you can get your confirm using javascript and postback or callback result to server.

but if you want to do this, this will help you :

A Simple ASP.NET Server Control: Message Box & Confirmation Box