js is turing complete. In theory you should be able to write an emulator for an OS using js your browser runs. Turns out people are doing this. From there it

js is turing complete. In theory you should be able to write an emulator for an OS using js your browser runs. Turns out people are doing this. From there its just the everday craziness of emulation. Emulating the instruction set, the IO devices, etc.