Web Bluetooth / Characteristic Properties (Async Await) Sample

Available in Chrome 55+ | 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 display all properties of a specific characteristic 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 Characteristic Properties (Promises) sample.

Live Output


JavaScript Snippet

async 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);
  }

  try {
    log('Requesting Bluetooth Device...');
    const device = await navigator.bluetooth.requestDevice({
      filters: [{services: [serviceUuid]}]});

    log('Connecting to GATT Server...');
    const server = await device.gatt.connect();

    log('Getting Service...');
    const service = await server.getPrimaryService(serviceUuid);

    log('Getting Characteristic...');
    const characteristic = await service.getCharacteristic(characteristicUuid);

    log('> Characteristic UUID:  ' + characteristic.uuid);
    log('> Broadcast:            ' + characteristic.properties.broadcast);
    log('> Read:                 ' + characteristic.properties.read);
    log('> Write w/o response:   ' +
      characteristic.properties.writeWithoutResponse);
    log('> Write:                ' + characteristic.properties.write);
    log('> Notify:               ' + characteristic.properties.notify);
    log('> Indicate:             ' + characteristic.properties.indicate);
    log('> Signed Write:         ' +
      characteristic.properties.authenticatedSignedWrites);
    log('> Queued Write:         ' + characteristic.properties.reliableWrite);
    log('> Writable Auxiliaries: ' +
      characteristic.properties.writableAuxiliaries);
  } catch(error) {
    log('Argh! ' + error);
  }
}