Just opening this again to mention this page, which has your answer: https://github.com/espruino/Espruino/blob/master/libs/README.md
@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.
Just opening this again to mention this page, which has your answer: https://github.com/espruino/Espruino/blob/master/libs/README.md