There are a lot of helpful posts in here for JavaScript, but I'm still struggling to make mine work.

We have varying levels of managers and executives with direct reports, and I have a Form/Approval Process with a dropdown to direct the form to the appropriate manager and then a lookup to forward it on to their VP/Exec for final review. 

If the "Manager" that is selected in the dropdown is the Exec, I'm trying to figure out how to use JavaScript to copy/overwrite the ID from the manager field into the Exec field. 

Your suggestions are greatly appreciated - thank you!