Imagine a form where the user has some required fields, and after scrolling down a way hits the "submit" button. On most forms I've seen, trying to submit with missing required fields will trigger some message to the user and the missing fields will be highlighted red - Amazon is a good example of this.
What I am wondering is at the bottom of a form, before hitting the submit button, would it be a bad idea to have a live-updating checklist of missing fields you need to fill in still? I've yet to see this anywhere, though I feel it could help users who may have skipped over a required field and forgotten. Something along the lines of a box that would say
The following fields still need to be filled in:
but still bring up a message/red-highlighting if they click submit anyway.