https://github.com/espruino/Espruino/tree/master/libs/js/rak
The rest of it is standard Espruino (in that repo) or standard JS modules which are at http://www.espruino.com/Modules
@Gordon started
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.
https://github.com/espruino/Espruino/tree/master/libs/js/rak
The rest of it is standard Espruino (in that repo) or standard JS modules which are at http://www.espruino.com/Modules