nodemailer error - nodemailer.createTransport不是函数

Question

我正在尝试第一次实现nodemailer并且收到以下终端错误：＆＃34; TypeError：nodemailer.createTransport不是函数＆＃34;

这是我的路线代码：

router.post('/reportHero', function(req, res){
  var emailBody = req.body;

  var transporter = nodemailer.createTransport({
    service: 'Gmail',
    auth: {
      user: 'gmail email address',
      pass: 'password'
    }
  });

  var mailOptions = {
    from: req.body.senderEmail,
    to: req.body.recipientEmail,
    subject: req.body.subject,
    text: req.body.text
  }

  transporter.sendMail(mailOptions, function(error, info){
    if(error){
      console.log(error);
      res.sendStatus(500);
    }else{
      console.log('Message sent: ' + info.response);
      res.sendStatus(200);
    };
  });
});

有谁知道我为什么会收到这个错误？