JavaScript 永远不会调用回调函数

Question

我正在尝试使用 nodemailer 在我的 SendMail 上调用回调函数。虽然函数执行成功并发送了邮件，但是在控制台记录“邮件已发送”的回调函数并没有执行。知道我遗漏了什么吗？

var email = 'receiver@gmail.com'
async.waterfall([
    function(done) {
        crypto.randomBytes(20, function(err, buf) {
          var token = buf.toString('hex');
          return done(err, token);
        });
    },
     function(token, done){
        //some code
        done(null,token);
    },
    function(token, done){
        if(token){
            var mailOptions = {
                to: email,
                from: 'mymail@gmail.com',
                subject: 'subject',
                text: 'text'
                };
            mailer.SendMail(mailOptions, function(err) {
                if(err){
                    console.log(err);
                }else {
                    console.log("no error");
                }
                console.log("sent mail");
                req.flash('info', 'An e-mail has been sent to ' + email + ' with further instructions.');
                console.log("mail sent");
                done(err, 'done');
            });
        }
        else return done("Account existiert nicht", null);
    }  
],
    function(err){
        console.log("final block");
        if(err){
            console.log(err);
            return res.status(500).send({msg:"error"});
        }
        else {
            return res.status(200).send({msg: "Reset Link has been sent to you."})
        }
    }
);

这是对应的SendMail()函数：

const nodemailer = require("nodemailer");

exports.SendMail = (msg) => {
    let transporter = nodemailer.createTransport({
        service: 'gmail',
        host: "smtp.gmail.com",
        secure: true,
        auth: {
            user: "mymail@gmail.com", // my mail
            pass: "mysecretpwd" // my password
        }
      });

    return transporter.sendMail(msg, function (error, info) {
        if(error) {
            return console.log(error);
        }
        console.log("Message sent "+ info.response) // this statement is showing on the console
      });
}

Answer 1

您的函数没有使用第二个参数（回调）。您可以使用类似的东西：

const nodemailer = require("nodemailer");

exports.SendMail = (msg, callback) => {
    let transporter = nodemailer.createTransport({
        service: 'gmail',
        host: "smtp.gmail.com",
        secure: true,
        auth: {
            user: "mymail@gmail.com", // my mail
            pass: "mysecretpwd" // my password
        }
      });

    return transporter.sendMail(msg, callback);
}

JavaScript 永远不会调用回调函数

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