I have an application that allows someone the ability view recently accessed files on their file system (provided they grant access). For example, if the name of my computer is David$ then it might present something like:

Last 3 accessed files:
Sales.csv     (1 hour ago)
My Movie.mov  (3 hours ago)
Contract.pdf  (3 hours ago)

It would also cache this information based on someone's computer. In other words, if I signed in to the application from my Phone, it would store/cache something different than if I signed in from my desktop computer, which would be different than if I signed in from my laptop.

Is there a certain identifier that can be used -- and is accessible from the browser in javascript that can be used to uniquely identify a physical device? (Note: I don't care about the IP being used or browser or anything outside of the physical device).

For mac-specific, I'd use this from the command line, but I'm looking for something that can be used in js and is more general:

david$ python -c "import subprocess,json;print(json.loads(subprocess.check_output( \
                 ['system_profiler', '-json' ,'SPHardwareDataType'])) \
                 ['SPHardwareDataType'][0]['platform_UUID'])"
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