CreateDeviceIdentity.js

// based on: https://docs.microsoft.com/en-us/azure/iot-hub/iot-hub-node-node-getstarted#create-a-device-identity
const iothub = require('azure-iothub');

const connectionString = '{iothub connection string}';
const registry = iothub.Registry.fromConnectionString(connectionString);
const device = {
  deviceId: 'myFirstNodeDevice'
};

registry.create(device, function(err, deviceInfo, res) {
  if (err) {
    registry.get(device.deviceId, printDeviceInfo);
  }
  
  if (deviceInfo) {
    printDeviceInfo(err, deviceInfo, res);
  }
});

const printDeviceInfo = (err, deviceInfo, res) => {
  if (err) console.error(err);
  if (deviceInfo) {
    console.log('Device ID: ' + deviceInfo.deviceId);
    console.log('Device key: ' + deviceInfo.authentication.symmetricKey.primaryKey);
  }
};