old_poweredup.js

(function() {
	'use strict';

	class PoweredUp {
		constructor() {
			this._EVENTS = {};
			this._PROMISES = {};

            this._CHARACTERISTIC = null;

			this._QUEUE = [];
			this._WORKING = false;
		}

		connect() {
            return new Promise( async function(resolve, reject){
				try {
		            let device = await navigator.bluetooth.requestDevice({
				        filters: [
				        	{ namePrefix: 'HUB' }
				        ],
				        optionalServices: [
					        '00001623-1212-efde-1623-785feabcd123'
					    ]
					});

					device.addEventListener('gattserverdisconnected', this._disconnect.bind(this));

					let server = await device.gatt.connect();
					let service = await server.getPrimaryService('00001623-1212-efde-1623-785feabcd123');

					this._CHARACTERISTIC = await service.getCharacteristic('00001624-1212-efde-1623-785feabcd123');
					this._CHARACTERISTIC.startNotifications();
					this._CHARACTERISTIC.addEventListener('characteristicvaluechanged', function(e) {
                        // received...
					}.bind(this));


		            resolve();
		        }
				catch(error) {
	                console.log('Could not connect! ' + error);
					reject();
				}
			});
        }

        drive(left, right) {
            this._queue(new Uint8Array([
                0x08, 0x00, 0x81, 0x39, 0x11, 0x02, left, right
            ]));
        }

        stop() {
            this._queue(new Uint8Array([
                0x08, 0x00, 0x81, 0x39, 0x11, 0x02, 0x00, 0x00
            ]));
        }

		addEventListener(e, f) {
			this._EVENTS[e] = f;
		}

		isConnected() {
			return !!this._CHARACTERISTIC;
		}

		_disconnect() {
            console.log('Disconnected from GATT Server...');

			this._CHARACTERISTIC = null;

			if (this._EVENTS['disconnected']) {
				this._EVENTS['disconnected']();
			}
		}

		_queue(message) {
			var that = this;

			function run() {
				if (!that._QUEUE.length) {
					that._WORKING = false;
					return;
				}

                that._WORKING = true;
                that._CHARACTERISTIC.writeValue(that._QUEUE.shift()).then(() => run() );
			}

            that._QUEUE.push(message);

			if (!that._WORKING) run();
        }
	}

    window.PoweredUp = new PoweredUp();
})();