Check if web form values have changed

Question

I have a multi-step form and user can navigate to any page to modify or add information. There is a menu that shows the current progress, the steps the user has completed, and allows to navigate to any completed or pending step.

In spite of a big button "Save and Continue" some users click this menu to navigate further. I have to check - if values have changed in a form and ask: "Save changes? Yes/No".

What is the best way (with minimum client-side JavaScript code) you suggest me to check if form values have changed?

Edited a bit later:

I forgot to tell that the multi-step form uses postback between steps.

Answer 1

The jQuery "Dirty Form" plugin may help you out here:

http://plugins.jquery.com/project/dirtyform