I have not tried this, but came across this some time ago:
http://www.4guysfromrolla.com/webtech/100604-1.shtml

Is there an easy way to tell if a change has been made on a page?

For example, I have a page that has about 30 fields on it.  I start out
getting any existing data from our sql tables and the user then will start
making changes (or he may not).

I would like to be able to ask him if he wants to save any changes he has
made.  But how do I tell if he has made any changes?

Thaanks,

Tom

Yes, you can.  Keep a hidden control in the page and update it through
javascript event (say onchange for textboxes), when the user changes
the data.  The only hitch is that if the user changes something, and
again puts back to what it was originally, you cannot really find out
with this approach.  For that you need to keep another copy of the
original data in hidden controls.  Hope this helps.

snt
http://www.flexoweb.com
http://www.onlinemall.com