nodestuff.js

// config.js
module.exports = {
  dev: {
    dbname: 'foo',
    host: '127.0.0.1',
    pass: 'bar',
    port: 1223
  },
  prod: {
    dbname: 'baz',
    host: '127.0.0.2',
    pass: 'bam',
    port: 1225  
  }
};

// db.js

module.exports = function (options) {
  var DB = {
    connection: null,
    connect: function (options) {
      if (this.connection) {
        return this.connection;
      }
      this.connection = new Whatever(options);
      return this.connection;
    }
  };
  
  return DB.connect(options);
};

// in der "app.js"
var config = require('./config.js')[process.env.NODE_ENV];
var db = require('./db.js')(config);
db.query('Select whatever from wherever');

// programm dann so starten
node index.js NODE_ENV=dev