Can you inherit private functions in JavaScript? -

i using closure create object private , public methods. looks -

var dog = (function() {     function dog() {}      var size = 'big';      var _privatesaysize = function() {         return 'i ' + size + ' dog.';     }      dog.prototype.publicsaysize = function() {         return _privatesaysize();     }      return dog; })(); 

but have object has private functions , inherited object. possible in javascript?

you want 1 instance inherit private state of instance? sure can in javascript. first need define utility function:

function weakbind(functable, prototype, state) {     return function () {         return functable.apply(this, object.getprototypeof(this) === prototype ?             [state].concat(array.prototype.slice.call(arguments)) : arguments);     }; } 

now can create our base class follows:

var dog = (function () {     function dog() {         if (this instanceof dog) {             // constructor code         } else return object.create(private);     }      var public = dog.prototype, private = object.create(public, {         size: {             value: "big"         }     });      public.saysize = weakbind(function (private) {         return "i " + private.size + " dog.";     }, public, private);      return dog; }()); 

now can create dog follows:

var dog = new dog; alert(dog.saysize()); // big dog. alert(dog.size);      // undefined 

we can inherit private state follows:

var chihuahua = (function () {     function chihuahua() {         dog.call(this);     }      var private = dog();      object.defineproperty(private, {         size: {             value: "small"         }     });      var public = chihuahua.prototype = object.create(dog.prototype);      public.saysize = weakbind(public.saysize, public, private);      return chihuahua; }()); 

now can create chihuahua follows:

var chi = new chihuahua; alert(chi.saysize());    // small dog. alert(chi.size);         // undefined 

see demo: http://jsfiddle.net/b3eyn/

note: wrote answer show it's possible inherit private state in javascript. advise not use pattern. if design code won't need inherit private state in first place.