how to execute C# code based on value returned from javascript function

I have C# code that I want to execute based on the value returned from javascript confirm box.



If confirm box is clicked on ok then I want my code to be executed else
not
something like this

I have a button event That I fire
Button_Event()
{
  for(i=0;i   {
    if(i%2)
    {
       // Javascript Confirm Box that I want to display
        If Javascript function value ==true;
        Execute Code
        //else
        continue
    }
Javascript Function
{
}


Please help me  as soon possible