I think this would help: https://www.silabs.com/community/wireless/bluetooth/knowledge-base.entry.html/2017/02/10/bluetooth_advertisin-hGsf
Basically:
@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 think this would help: https://www.silabs.com/community/wireless/bluetooth/knowledge-base.entry.html/2017/02/10/bluetooth_advertisin-hGsf
Basically: