First, thanks in advance.

I need to create a pdf that calculates travel time for my fellow employees. I need users to enter a start time (HH:MM format) and an end time (HH:MM format as well obviously) and have the total travel time (again back HH:MM) appear in another field. My javascript-fu is both old and very rusty so I have not been able to get this work. I have thrown several attempts at it, and even though the console in both Foxit and Adobe tell me that the code runs successfully, I am getting no output. I can't even tell if any of the code I have tried is working.

Any help would be greatly appreciated!