R2D2

connect_the_droid.js

const noble = require('noble');

let connectTheDroid = (address) => {
    return new Promise((resolve, reject) => {
        noble.on('discover', (peripheral) => {
            if (peripheral.address === address) {
                noble.stopScanning();
                peripheral.connect( (e) => {
                    peripheral.discoverServices([CONNECT_SERVICE], (error, services) => {
                        services[0].discoverCharacteristics([CONNECT_CHAR], (error, characteristics) => {
                            characteristics[0].write(Buffer.from(MSG_CONNECTION), true, (error) => {
                                peripheral.discoverServices([MAIN_SERVICE], (error, services) => {
                                    services[0].discoverCharacteristics([MAIN_CHAR], (error, characteristics) => {
                                        resolve(characteristics[0]);
                                    });
                                });
                            });
                        });
                    });
                });
            }
        });

        noble.on('stateChange', (state) => {
            if (state === 'poweredOn') {
                noble.startScanning();
            } else {
                noble.stopScanning();
            }
        });
    });
}