Access Javascript object - Scope issue with Node.js

Question

I'd like to fetch mail from a mailbox regularly using a Node daemon. The call to the connection method is made in app.js.

The javascript file I use to connect to my mailbox (mail.js):

var imap = new Imap({
    user: '[email protected]',
    password: config.get.gmail_password,
    host: 'xxxxx',
    port: 993,
    tls: true
});

var fetchMail = function()
{
    console.log('Connection');
    imap.connect();
};

//fetchMail();

imap.once('ready', function() {
   console.log('Ready'); 

   imap.search([ 'UNSEEN', ['FROM', 'xxxx'] ], function(err, results)
   {
       // Do Stuff
   }

exports.fetchMail = fetchMail;

If I use fetchMail() directly from mail.js, everything is fine.

However, when I try to call it from app.js:

var mail = require('./js/mail');
mail.fetchMail()

Then, the method stay in the fetchMail() function from mail.js and the imap.once('ready', function())is never triggered.

I guess it is a scope issue with the imap var in mail.js.

How can I fix this?

EDIT

I solved this in a way I don't like. I wrote everything's related to the imap var inside the fecthMail()function.

Please, do not hesitate to write a more efficient answer to this.

Not in app.js, you need to first export from mail.js then use it app.js by doing require — gurvinder372
– gurvinder372, Commented May 3, 2016 at 11:09

Madara's Ghost · Accepted Answer · 2016-05-03 10:15:32Z

1

You would need to bind the event every time you connect. So like so:

var fetchMail = function()
{
    console.log('Connection');

    imap.once('ready', function() {
      console.log('Ready');         
      imap.search([ 'UNSEEN', ['FROM', 'xxxx'] ], function(err, results)
      {
        // Do Stuff
      }
    }
    imap.connect();
};

answered May 3, 2016 at 10:15

Madara's Ghost

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1 Comment

Mornor Over a year ago

Thanks ! I still am blocked in the connection phase. It would also help me if you could may be explain a bit your solution ? :)

Martin Gottweis · Accepted Answer · 2016-05-03 10:17:22Z

0

The approach and idea is great. All you need is to change the syntax of mail.js file to return a module. In another words when you do

var mail = require('./js/mail');

what do you expect to be in the mail variable?

You might need to change logic around, but try this:

var MailHandler = function () {}

var imap = new Imap({
    user: '[email protected]',
    password: config.get.gmail_password,
    host: 'xxxxx',
    port: 993,
    tls: true
});

MailHandler.init = function(){
  imap.once('ready', function() {
     console.log('Ready'); 

     imap.search([ 'UNSEEN', ['FROM', 'xxxx'] ], function(err, results)
     {
         // Do Stuff
     }
  }
}

MailHandler.fetchMail = function()
{
  console.log('Connection');
  imap.connect();
};

//fetchMail();

module.exports = new MailHandler()

answered May 3, 2016 at 10:17

Martin Gottweis

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4 Comments

Mornor Over a year ago

Thank you :) How yould I then call the fetchMail() function inside app.js?

Martin Gottweis Over a year ago

Easy: mail.fetchMail()

Mornor Over a year ago

I do not think so. Since that when you export the MailHandler module, you create a instance of itself. This instance is created by calling imap.once('ready', function(){}); which is triggered when imap.connect() is done. I think there is something not right in this approach. But I may be wrong, could you explain?

Martin Gottweis Over a year ago

Hmm. You'll have to find out what works for you. But what's for sure, when you do the require it will load whatever is inside, but it will not register the once event.

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