Creating a mail service with NodeJs

Question

I have two files, my app.js and my mailer module called mailer.js.

My app.js should send several emails when starting the application.

const express = require('express');
const app = express();
const mailer = require('./Server/mailer');

mailer.sendHtmlMail(["email1", "email2"], "Test Email", "<p>Success!</p>");

app.listen(8888, function () {
    console.log('Server running on port 8888');
});

And my mailer.js executes the mail service

    const nodemailer = require('nodemailer');

    const senderMail = "myEmail";

    const emailTransporter = nodemailer.createTransport({
      service: 'yahoo',
      auth: {
        user: senderMail,
        pass: 'pw'
      }
    });

    function getMailReceivers(mailReceivers){ // convert the string array to one string
      var receivers = "";

      for(var i = 0; i < mailReceivers.length; i++){
        receivers += mailReceivers[i];

        if(i < mailReceivers.length - 1)
            receivers += ", ";
      }

      return receivers;
    }

    function getMailOptions(mailReceivers, subject, html){ // set the mail options and return them
      return {
        from: senderMail,
        to: getMailReceivers(mailReceivers),
        subject: subj,
        html: content
      };
    }

    module.exports = function () { // export the sendMail function here

    sendHtmlMail: function(mailReceivers, subject, html){ // send the email
        emailTransporter.sendMail(getMailOptions(mailReceivers, subject, html), function(error, info){
          if (error) {
            throw error;
          } else {
            console.log(info.response);
          }
        });
      }

    };

I get this error message

SyntaxError: Unexpected token (
    at createScript (vm.js:80:10)
    at Object.runInThisContext (vm.js:139:10)
    at Module._compile (module.js:599:28)
    at Object.Module._extensions..js (module.js:646:10)
    at Module.load (module.js:554:32)
    at tryModuleLoad (module.js:497:12)
    at Function.Module._load (module.js:489:3)
    at Module.require (module.js:579:17)
    at require (internal/module.js:11:18)
    at Object.<anonymous> (C:\...\app.js:3:16)

but I don't understand it, does

at Object. (C:...\app.js:3:16)

say there is an error in my mailer object (line 3) on line 16? I can't find any syntax error there..

Answer 1

You should export an object like that (not a function):

module.exports = { 

  sendHtmlMail: function(mailReceivers, subject, html){ // send the email
      emailTransporter.sendMail(getMailOptions(mailReceivers, subject, html), function(error, info){
        if (error) {
          throw error;
        } else {
          console.log(info.response);
        }
      });
    }

}

Now, in your app.js you can import sendHtmlMail

const { sendHtmlMail } = require('./mailer');

And use it like this:

sendHtmlMail(["email1", "email2"], "Test Email", "<p>Success!</p>");

Or:

const mailer = require('./mailer');

mailer.sendHtmlMail(["email1", "email2"], "Test Email", "<p>Success!</p>");

I hope you will find this information useful

Answer 2

I would start from correcting

sendHtmlMail: function(mailReceivers, subject, html){

to

function sendHtmlMail(mailReceivers, subject, html){

or, if you really need the object literal syntax, find a valid place in your code where this is allowed - it definitely is an error in the scope it is defined.

Edit: it is possible that you wanted to export a function returning an object, that would be

module.exports = function () { // export the sendMail function here

  return {
    sendHtmlMail: function (mailReceivers, subject, html) { // send the email
  emailTransporter.sendMail(getMailOptions(mailReceivers, subject, html), function (error, info) {
        if (error) {
          throw error;
        } else {
          console.log(info.response);
        }
      });

    }
  }

or simply an object with the function

module.exports = { // export the sendMail function here

    sendHtmlMail: function (mailReceivers, subject, html) { // send the email
  emailTransporter.sendMail(getMailOptions(mailReceivers, subject, html), function (error, info) {
        if (error) {
          throw error;
        } else {
          console.log(info.response);
        }
      });

  }
}

Answer 3

The end of your mailer.js file is where the problem is. That exception you see comes from line 3 of app.js because that's where you require() the other file.

The problem is that you've mixed up function instantiation with object initiailzation:

module.exports = function () { // export the sendMail function here

sendHtmlMail: function(mailReceivers, subject, html){ // send the email
    emailTransporter.sendMail(getMailOptions(mailReceivers, subject, html), function(error, info){
      if (error) {
        throw error;
      } else {
        console.log(info.response);
      }
    });
  }

};

Your code expects that module to export an object with a sendHtmlMail property, so that should be an object initializer:

module.exports = { // export the sendMail function here

  sendHtmlMail: function(mailReceivers, subject, html){ // send the email
    emailTransporter.sendMail(getMailOptions(mailReceivers, subject, html), function(error, info){
      if (error) {
        throw error;
      } else {
        console.log(info.response);
      }
    });
  }
};