Available in Chrome 53+ | 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, Mac, and Windows 10.
This sample illustrates the use of the Web Bluetooth API to discover all
accessible primary services with server.getPrimaryServices and their
characteristics 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 Discover Services &
Characteristics Sample (Async Await) sample.
function onButtonClick() {
// Validate services UUID entered by user first.
let optionalServices = document.querySelector('#optionalServices').value
.split(/, ?/).map(s => s.startsWith('0x') ? parseInt(s) : s)
.filter(s => s && BluetoothUUID.getService);
log('Requesting any Bluetooth Device...');
navigator.bluetooth.requestDevice({
// filters: [...] <- Prefer filters to save energy & show relevant devices.
acceptAllDevices: true,
optionalServices: optionalServices})
.then(device => {
log('Connecting to GATT Server...');
return device.gatt.connect();
})
.then(server => {
// Note that we could also get all services that match a specific UUID by
// passing it to getPrimaryServices().
log('Getting Services...');
return server.getPrimaryServices();
})
.then(services => {
log('Getting Characteristics...');
let queue = Promise.resolve();
services.forEach(service => {
queue = queue.then(_ => service.getCharacteristics().then(characteristics => {
log('> Service: ' + service.uuid);
characteristics.forEach(characteristic => {
log('>> Characteristic: ' + characteristic.uuid + ' ' +
getSupportedProperties(characteristic));
});
}));
});
return queue;
})
.catch(error => {
log('Argh! ' + error);
});
}
/* Utils */
function getSupportedProperties(characteristic) {
let supportedProperties = [];
for (const p in characteristic.properties) {
if (characteristic.properties[p] === true) {
supportedProperties.push(p.toUpperCase());
}
}
return '[' + supportedProperties.join(', ') + ']';
}