I actually use it in the EspruinoHub IDE page: https://github.com/espruino/EspruinoHub/blob/master/www/ide.html
Also to serve the IDE directly off of something like an Espruino WiFi: http://forum.espruino.com/conversations/318472/
@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.
I actually use it in the EspruinoHub IDE page: https://github.com/espruino/EspruinoHub/blob/master/www/ide.html
Also to serve the IDE directly off of something like an Espruino WiFi: http://forum.espruino.com/conversations/318472/