Eddystone UID scanning?

NRF.findDevices should be what you need: http://www.espruino.com/Reference#l_NRF_­findDevices

NRF.findDevices(function(devices) {
  devices.forEach(function(device) {
    console.log(device);
    // I believe you'll find a device.servicedata field that'll contain the raw information for any Eddystone beacons
  });
}, 1000);