How To Dispaly Confirm Box On Code Behind

See more:

C#

Javascript

C#4.0

ASP.NET4

Hi All

I need to dispay confirm box on server Side.. senario is like Im Trying To upload Image During Upload Im Checking some properties like Image type,image size, etc.. While Uploading i want to check properties like

if(type=="xxxx")

{

confirmbox("  ");

if(confirmvalue=="yes")

{

next condition

}

else

{

exit ;

}

}

like this i want check different properies of file.. i tried

this.Page.ClientScript.RegisterStartupScript(this.GetType(), "alert", "alert('You clicked YES!')", true);

but it wont work