Node JS return hostname

I'm still learning Node JS and javascript and have an app. I have a configuration file where I need to grab the hostname of the server on Ubuntu 12.04

I tried something like:

 window.location.hostname

But that did not work. Sample code below:

exports.config = {
    app_name : [ window.location.hostname ]
}

If I use a string, it will load fine, but this is going to be managed through Github and needs to be differentiated when the app loads.