Javascript Calling & Website Log File

Good day, all. We need some more work done and was wondering if you could help us with that? It involves creating a system that when a user logs in, depending on which user it is, a specific javascript file (for menu navigation) loads. For example: - when John Smith logs in (MySQL database), only a specific menu loads for his navigation. I realise I would need to create the javascript menus, which is fine, even if it is on an individual basis for each user. So basically, we would need to a specific javascript file (for menu navigation) for each user to load on each page when the user is logged in. Also, if it is possible, perhaps create a log file for people who log in, times, etc. Look forward to your replies. Andrew