从Node JS中的另一个模块导入函数

Question

Importing certain function from some folder which has needed module with this function doesn't work.

I'm using nodemailer for sending emails. I have 3 different folders with modules. The problem is in importing (require) email sending function to current module from another one. It becomes undefined and error is myFunc is not a function . I'm doing pretty simple things like requiring function from folder with index.js which includes needed function. But it becomes undefined when I try to use it.

services/mailTransport.js

const nodemailer = require('nodemailer');

const mailTransporter = nodemailer.createTransport({
    host: 'smtp.gmail.com',
    port: 587,
     secure: false, 
    auth: {
      user: 'test@test.com',
      pass: 'myPassword'
    }
});

module.exports = mailTransporter;

services/index.js

const mailTransporter = require("./mailTransporter");
module.exports = { mailTransporter }

utils/mailTemplate.js

const { mailTransporter } = require("../services");

const sendEmail = function (obj, msg) {
return new Promise( (res, rej) => {
    let mailOptions = {
        from: 'test@test.com',
        to: `${obj.to}`,
        subject: `${obj.subject}`,
        text: "plain text",
        html: "<b>" + msg + "</b>"
    };
    mailTransporter.sendMail(mailOptions, (error, info) => {
        mailTransporter.close();
        if (error) {
            rej(error);
        }
    console.log('Message sent: %s', info.messageId);
    res(info.messageId);
    });
})
}

module.exports = { sendEmail };

And finally I want to use it here in projects/emails.js

const { sendEmail } = require("../utils/mailTemplate");
const { vendorNotificationMessage } = require("../utils/emailMessages");

async function notifyVendors(steps) {
try {
    for(let step of steps) {
        if(step.vendor) {
            const message = vendorNotificationMessage(step);
            step.to = step.vendor.email;
            step.subject = "Step cancelling notification!";
            await sendEmail(step, message);
        }
    }
} catch(err) {
    console.log(err);
    console.log("Error in notifyVendors");
}
}

module.exports = { notifyVendors };

I expect that email will be sent using that sendEmail function. But it stops with the error TypeError: sendEmail is not a function .

Answer 1

The correct syntax for exporting something from a module is

exports.globalObjectName = localObjectName

So in your first file the export statement should look like this

exports.mailTransporter = mailTransporter

Answer 2

I do not think that you need {} when you use module.exports and require. Try module.exports = sendEmail ; and const sendEmail = require("../utils/mailTemplate");