Puck advertise data when ibeacons with specific uuid detected

Hello, I'm building an android app and I was wondering how I can advertise my puck's data only when ibeacon devices are detected from puck.. Could you please give me some info about that and probably part of code? thanks in advance!

You can use NRF.findDevices to check for the beacons advertising around you can can then do things based on that: http://www.espruino.com/Reference#l_NRF_findDevices

Eg.

function checkPresence() {
  NRF.findDevices(function(devices) {
    var found = false;
    for (var dev in devices) {
      if (dev.name == "whatever") found = true;
    }
    if (found) start advertising
    else stop advertising;
  }, 1000); // scan for 1 second
}
setInterval(checkPresence, 5*60000); // check once every 5 minutes

However actually checking for surrounding beacons takes a lot of power, so you don't want to do it often, or for long. The example above does 1 second every 5 minutes, which is still quite a lot. If you were doing this to save power you're probably best off not bothering and just advertising regardless.

Thanks for your responce, but this is

Uncaught Error: Field or method "name" does not already exist, and can't create it on Number
 at line 5 col 14
      if (dev.name == "DiamondBeacon") found = true;

and when I use the simple example no name is displayed.. I want to scan with id(Mac address).

NRF.findDevices(print)

Ahh, try:

    devices.forEach(function(dev) {
      if (dev.name == "whatever") found = true;
    });