There's a bunch of info on the power supply circuit here: http://www.espruino.com/EspruinoBoard
It's routed via a 1 Amp thermal fuse, and in USB's case, a diode.
@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.
There's a bunch of info on the power supply circuit here: http://www.espruino.com/EspruinoBoard
It's routed via a 1 Amp thermal fuse, and in USB's case, a diode.