Trying to get my device working...

@Gordon trying another method, by mac address. Also disconnects from IDE without changing the characteristic:

var gatt;
NRF.connect("d4:df:0a:04:44:03").then(function(g) {
  gatt = g;
  return gatt.getPrimaryService("bbc21523-008e-fe6b-28ee-d6a44f9cb5da");
}).then(function(service) {
  return service.getCharacteristic("bbc21525-008e-fe6b-28ee-d6a44f9cb5da");
}).then(function(characteristic) {
  characteristic.writeValue(0xff);
}).then(function() {
  gatt.disconnect();
  console.log("Done!");
});