It's all in C. https://github.com/espruino/Espruino/blob/master/libs/network/jswrap_net.c
@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.
It's all in C. https://github.com/espruino/Espruino/blob/master/libs/network/jswrap_net.c