Node.js - use of module.exports as a constructor, Essential Node.js patterns and snippets

/***************************/ constructor version first

1.

function Login(base, req, res) {
    this._base = base;
    this._req = req;
    this._res = res;
    this.title = 'Login_title';
    this.description = 'Login_description';
}
Login.prototype = {
    constructor: Login,
    description: 'default_description',
    auth: function (args) {
        this._res.send(this.title + " => " + args + " , " + this.description);
    }
};
module.exports = Login;

/**************************/ constructor version second

2.

 class Login {
    constructor(base, req, res) {
        this.base = base;
        this.req = req;
        this.res = res;
        this.foo = 10;
    }
    auth(args) {
        this.res.json(this.foo + ';;;' + args);
    }
}
module.exports = Login;

****************************************************


var _constructor = require('./login');
var _object = new _constructor(base, req, res);
this.function = "auth";

if (typeof _object[this.function] === 'function') {
         _object[this.function]("passed args");
}


***********************************************************

1.2 Accessing global values from objects

// constructor
var Class = function(global, value2) {
  this.global = global;
}
// access using this.global in class methods

1.3 Factory pattern

// Constructor
var Class = function(value1, value2) { ... }
// Factory
Class.factory(value1) { return new Class(value1, "aaa"); }
// properties and methods
Class.prototype = { ... };

1.4 Sharing state between modules

var Common = {
  util: require('util'),
  fs:   require('fs'),
  path: require('path')
};

module.exports = Common;

// in other modules
var Common = require('./common.js');

1.5 Singleton class (added Feb 2011)

var Singleton = (function() {
   var private_variable = 'value';
   function private_function() {
      ...
   }
   function public_function() {
      ...
   }
  return {
      public_function: public_function
  };
})();