I am writing an application that if the user hits back, it may resend the same information and mess up the flow and integrity of data. How do I disable it for users who are with and without javascript on?
It's not possible, sadly. However, consider your applications navigation model. Are you using Post/Redirect/Get PRG Model? http://en.wikipedia.org/wiki/Post/Redirect/Get?
This model is more back button friendly than the Postback model.