How to put nconf property inside a Javascript object

Question

I am loading config.json file using nconf like below:

nconf.file({ file: '../config.json' });

. I am using a property in that config file which I can print on console and it works:

console.log('mailhost: '+ nconf.get('mailhost'));

But my requirement is to have an object where I can dynamically put nconf properties like so:

var mailConfig = {
    "mailhost": nconf.get('mailhost')
};
console.log('mailConfig: '+ JSON.stringify(mailConfig));

The above doesn't work as it prints empty object on console.

However, if I happen to load the config.json file using node like so:

var config = require('../config.json');

And use it to do exact same I did with nconf then it works well:

    var mailConfig = {
    "mailhost": config.mailhost
};
console.log('mailConfig: '+ JSON.stringify(mailConfig));

What am I missing?