How I do private and public in JavaScript. No “this”, no “new”! Drawback compared to .prototype: Objects hold copies of functions.

test.js

// Factory function

var Greeter = function(config) 
{
    // Hold public and private variables and functions in two objects:
    
    var _public = { };
    var _private = { };

    // Storing "constructor" parameters in a private variable
    
    _private.config = (config || { });

    // Private method
    
    _private.getName = function()
    {
        return (_private.config.name || 'unknown');
    };

    // Public method
    
    _public.greet = function()
    {
        alert('Hello ' + _private.getName());
    }; 
    
    // Return object with public variables and methods
    
    return _public;
};

// Usage:

// 1. Create an object

var greeter1 = Greeter({ name: 'World' });

// 2. Call a public method

greeter1.greet();