Review on mobile-detect.js by Brody Jacobs

It detects all kinds of devices, not just iPhones but also iPads and android tablets. You can set it up to detect other things as well if you ever need. I have used this in my work for detecting phones or computers when people come into our office that are working remotely. We usually use VPNs anyway so this makes sense. If they don't want to be detected then there isn't much we can do about that. So far nothing major has popped up with any issues. They will have some sort of notification system where their employees know what kind of phone/device was being used by them. This way we'll know who's coming in and out of the building without having to ask someone directly each time.