DefinitelyTyped/types/web-bluetooth/web-bluetooth-tests.ts

// Example 1 (from the spec):
let chosenHeartRateService: BluetoothRemoteGATTService = null;

navigator.bluetooth.requestDevice({
    filters: [{
        services: ['heart_rate'],
    }]
}).then((device: BluetoothDevice) => device.gatt.connect())
    .then((server: BluetoothRemoteGATTServer) => server.getPrimaryService('heart_rate'))
    .then((service: BluetoothRemoteGATTService) => {
        chosenHeartRateService = service;
        return Promise.all([
            service.getCharacteristic('body_sensor_location')
                .then(handleBodySensorLocationCharacteristic),
            service.getCharacteristic('heart_rate_measurement')
                .then(handleHeartRateMeasurementCharacteristic),
        ]);
    });

function handleBodySensorLocationCharacteristic(characteristic: BluetoothRemoteGATTCharacteristic) {
    if (characteristic === null) {
        console.log("Unknown sensor location.");
        return Promise.resolve();
    }

    // not from the spec - exercising additional APIs
    const buffer = new Uint8Array(0);
    characteristic.writeValue(buffer);
    characteristic.writeValueWithResponse(buffer);
    characteristic.writeValueWithoutResponse(buffer);

    return characteristic.readValue()
        .then(sensorLocationData => {
            let sensorLocation = sensorLocationData.getUint8(0);
            switch (sensorLocation) {
                case 0: return 'Other';
                case 1: return 'Chest';
                case 2: return 'Wrist';
                case 3: return 'Finger';
                case 4: return 'Hand';
                case 5: return 'Ear Lobe';
                case 6: return 'Foot';
                default: return 'Unknown';
            }
        }).then(location => console.log(location));
}

function handleHeartRateMeasurementCharacteristic(characteristic: BluetoothRemoteGATTCharacteristic) {
    return characteristic.startNotifications()
        .then(char => {
            characteristic.addEventListener('characteristicvaluechanged',
                onHeartRateChanged);
        });
}

function onHeartRateChanged(event: Event) {
    let characteristic = event.target as BluetoothRemoteGATTCharacteristic;
    console.log(parseHeartRate(characteristic.value));
}

function parseHeartRate(data: DataView) {
    let flags = data.getUint8(0);
    let rate16Bits = flags & 0x1;
    let result: any = {};
    let index = 1;
    if (rate16Bits) {
        result.heartRate = data.getUint16(index, /*littleEndian=*/true);
        index += 2;
    } else {
        result.heartRate = data.getUint8(index);
        index += 1;
    }
    let contactDetected = flags & 0x2;
    let contactSensorPresent = flags & 0x4;
    if (contactSensorPresent) {
        result.contactDetected = !!contactDetected;
    }
    let energyPresent = flags & 0x8;
    if (energyPresent) {
        result.energyExpended = data.getUint16(index, /*littleEndian=*/true);
        index += 2;
    }
    let rrIntervalPresent = flags & 0x10;
    if (rrIntervalPresent) {
        let rrIntervals: number[] = [];
        for (; index + 1 < data.byteLength; index += 2) {
            rrIntervals.push(data.getUint16(index, /*littleEndian=*/true));
        }
        result.rrIntervals = rrIntervals;
    }
    return result;
}

// Example from the scanning spec
navigator.bluetooth.requestLEScan({
    acceptAllAdvertisements: true,
}).then((scan) => {
    console.log('Scan started with:');
    console.log(' acceptAllAdvertisements: ' + scan.acceptAllAdvertisements);
    console.log(' active: ' + scan.active);
    console.log(' keepRepeatedDevices: ' + scan.keepRepeatedDevices);
    console.log(' filters: ' + JSON.stringify(scan.filters));

    navigator.bluetooth.addEventListener('advertisementreceived', event => {
        console.log('Advertisement received.');
        console.log('  Device Name: ' + event.device.name);
        console.log('  Device ID: ' + event.device.id);
        console.log('  RSSI: ' + event.rssi);
        console.log('  TX Power: ' + event.txPower);
        console.log('  UUIDs: ' + event.uuids);
        event.manufacturerData.forEach((valueDataView, key) => {
            logDataView('Manufacturer', key, valueDataView);
        });
        event.serviceData.forEach((valueDataView, key) => {
            logDataView('Service', key, valueDataView);
        });
    });

    setTimeout(stopScan, 10000);
    function stopScan() {
        console.log('Stopping scan...');
        scan.stop();
        console.log('Stopped.  scan.active = ' + scan.active);
    }
});

/* Utils */
const logDataView = (labelOfDataSource: string, key: string | number, valueDataView: DataView) => {
    const array = new Uint8Array(valueDataView.buffer);
    const hexString = Array(array.length).map((_, index) => {
        return `0${array[index].toString(16)}`.slice(-2);
    }).join(' ');
    const textDecoder = new TextDecoder('ascii');
    const asciiString = textDecoder.decode(valueDataView.buffer);
    console.log(`  ${labelOfDataSource} Data: ${key}
        (Hex): ${hexString}
        (ASCII): ${asciiString}
    `);
};