In node, you can tell your program to do two different things depending on whether the code is run from require('./something.js') or node something.js. This is useful if you want to interact with one of your modules independently.

if (!module.parent) {
    // ran with `node something.js`
    app.listen(8088, function() {
        console.log('app listening on port 8088');
} else {
    // used with `require('/.something.js')`
    module.exports = app;

See the documentation for modules for more info.