You just need to use NRF.setAdvertising. There's a quick run-down of BLE and which functions in Puck.js you use for it here that might be handy: http://www.espruino.com/About+Bluetooth+LE
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.
You just need to use
NRF.setAdvertising
. There's a quick run-down of BLE and which functions in Puck.js you use for it here that might be handy: http://www.espruino.com/About+Bluetooth+LEThere's an example here that uses Manufacturerdata advertising as well that might be interesting: http://www.espruino.com/Puck.js+Advertising