Web Bluetooth / Get Descriptors Sample

Available in Chrome 57+ | View on GitHub | Browse Samples

The Web Bluetooth API lets websites discover and communicate with devices over the Bluetooth 4 wireless standard using the Generic Attribute Profile (GATT). It is currently partially implemented in Android M, Chrome OS, Linux, and Mac.

This sample illustrates the use of the Web Bluetooth API to get all characteristic's descriptors of an advertised service from a nearby Bluetooth Low Energy Device. You may want to try this demo with the BLE Peripheral Simulator App from the Google Play Store and check out the Get Descriptors (Async Await) sample.

Live Output


JavaScript Snippet

function onButtonClick() {
  let serviceUuid = document.querySelector('#service').value;
  if (serviceUuid.startsWith('0x')) {
    serviceUuid = parseInt(serviceUuid);
  }

  let characteristicUuid = document.querySelector('#characteristic').value;
  if (characteristicUuid.startsWith('0x')) {
    characteristicUuid = parseInt(characteristicUuid);
  }

  log('Requesting Bluetooth Device...');
  navigator.bluetooth.requestDevice({filters: [{services: [serviceUuid]}]})
  .then(device => {
    log('Connecting to GATT Server...');
    return device.gatt.connect();
  })
  .then(server => {
    log('Getting Service...');
    return server.getPrimaryService(serviceUuid);
  })
  .then(service => {
    log('Getting Characteristic...');
    return service.getCharacteristic(characteristicUuid);
  })
  .then(characteristic => {
    log('Getting Descriptors...');
    return characteristic.getDescriptors();
  })
  .then(descriptors => {
    log('> Descriptors: ' +
      descriptors.map(c => c.uuid).join('\n' + ' '.repeat(19)));
  })
  .catch(error => {
    log('Argh! ' + error);
  });
}