Async await Example.

async-await

/**
 * without using async/await
 */
exports.updateUserAndSendEmail = (req, res) => {
  User.findOne({ email: req.body.email }, (error, retrievedUser) => {
    if (error) {
      console.log('error');
    }
    if(retrievedUser) {
      User.update({ email: email }, { name: 'XYZ' }, (error, result) => {
        if (error) {
          console.log('error', error);
        }
        EmailService.send(req.body.email, (error, result) => {
          console.log('error', error);
          console.log('result', result);
        });
      });
    }
  });
};


/**
 * With using async/await 
 */
exports.updateUserAndSendEmail = async (req, res) => {
  try {
    const retrievedUser = await User.findOne({ email: req.body.email });
    if (retrievedUser) {
      const updatedUser = await User.update({ email: req.body.email }, { name: 'XYZ' });
      const emailResult = await EmailService.send(req.body.email);
    }
  } catch (error) {
    console.log('error', error);
  }
};