Trying to understand BLE advertising

Ok, it's fixed :) If you try out a build from http://www.espruino.com/binaries/travis/master/

Then something like this should work fine:

NRF.setAdvertising([
require("ble_ibeacon").get({
    uuid : beaconUUID,    // iBeacon uuid
    major : beaconMajor,  // optional
    minor : beaconMinor,  // optional
    rssi : -59            // optional RSSI at 1 meter distance in dBm
  }),
{
    0x1815 : [button.single, button.long],
    0x180F : [metrics.battery],
    0x1809 : [metrics.temperature],
    0x181A : [metrics.light]
}],{ interval : 375 });