But that's unlikely to work. It might be possible to modify, but that port was done by the guys at ST themselves, so I couldn't be much help - except to say that the code you'd be dealing with is in the stm32_ll directories: https://github.com/espruino/Espruino/tree/master/targets/stm32_ll
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
There's a port to the L476 available here: http://www.espruino.com/binaries/travis/master/
But that's unlikely to work. It might be possible to modify, but that port was done by the guys at ST themselves, so I couldn't be much help - except to say that the code you'd be dealing with is in the stm32_ll directories: https://github.com/espruino/Espruino/tree/master/targets/stm32_ll