gistfile1.js

// FIRST WAY

//routes.js
module.exports = function (app, client, config) {
  var Index = require('../controllers/index')
    , index = new Index(app, client, config);
  app.get('/', index.index);
};

//index.js
module.exports = function (app, client, config) {
  this.index = function(req, res, next) {
    res.json('index');
  };
};

// SECOND WAY

//routes.js
module.exports = function (app, client, config) {
  var index = new require('../controllers/index')(app, client, config);
  app.get('/', index.index);
};

//index.js
module.exports = function (app, client, config) {
  var index = function index(req, res, next) {
    res.json('index');
  };

  return {
    index: index
  };
};