Well you could set a cookie, if he trys to sumbit and the cookie is already set, ie hes already submitted, generate an error.
I use this kinda system to stop double submits.
If you want to go via Javascript, do it all in a new window in which they have to submit the data, don't allow a toolbar in this window so they can't refresh, they also can't go back or anything unless you use further JS to generate a link for this.