NG Beacon controlling a Magic Blue bulb based on distance

ng-beacon-bulb-rssi.js

var bulbDevice = null;
var bulbChar = null;

function setColor(r, g, b) {
  try {
    bulbChar.writeValue(new Uint8Array([0x56, r, g, b, 0, 0xf0, 0xaa]));
  } catch (e) {
  }
}

function startLoop(char) {
  console.log('Connected !');
  var samples = [];
  bulbDevice.gatt.setRSSIHandler(rssi => {
    samples.unshift(rssi);
    if (samples.length > 10) {
      samples.pop();
    }
    var avg = -1 * samples.reduce((x,y)=>x+y) / samples.length;
    var threshold = 60;
    if (avg <= threshold)
      setColor(Math.round(threshold - avg) * 4, 0, 0);
    else
      setColor(0, 0, 0);
  });
  bulbChar = char;
}

(NRF.requestDevice({ filters: [{ services: ['ffe5'] }] })
  .then(device => {
    bulbDevice = device;
    return device.gatt.connect(); 
  })
  .then(gatt => gatt.getPrimaryService('ffe5'))
  .then(service => service.getCharacteristic('ffe9'))
  .then(startLoop));