Best way to implement a prompt to "Save"

Any suggestions on implementing a prompt for users to save after they have changed form values. I was going to implement a variable and set it using the change/update methods on each form field and then clear the variable on save. I have quite a few fields so was hoping someone had a smarter solution, sort of value changed at a form level.

Thanks, Paul

This thread might be relevant.

Thanks Tom, will give it a go