Private fields in js

PrivateFieldsModule.js

//module version

var Module = (function (window) {
    function privateFunction() {
        console.log('pass');
    };

    var privateClass = function () {};

    var publicClass = function () {};
    publicClass.prototype.publicMethod = function () {
        privateFunction(); // ...
    };
    
    return { // Экспортируем
        publicClass: publicClass
    };
}(this));

// Используем
(new Module.publicClass()).publicMethod();

PrivateFieldsSimple.js

//typical implementation

// our constructor
function Person(name, age){
    this.name = name;
    this.age  = age;
};

// prototype assignment
Person.prototype = new function(){

    // we have a scope for private stuff
    // created once and not for every instance
    function toString(){
        return this.name + " is " + this.age;
    };

    // create the prototype and return them
    this.constructor = Person;

    this._protectedMethod = function (){
        // act here
    };

    this.publicMethod = function() {
        this._protectedMethod();
    };

    // "magic" toString method
    this.toString = function(){
         // call private toString method
         return toString.call(this);
    }
};