confirmation box in asp.net using javascript

Your code won't even compile as you have an equals sign where there should be a plus sign. It's also worth using the proper brackets with this sort of thing to reduce the risk of errors.

The following works fine for me:

String doSomething = "alert('true');";

Response.Write("<Script>if(confirm('Data updated Any more data you add ??')){ " + doSomething + "}else{alert('false');}</Script>");