function extend(child, parent) {

  var f = function () {};

  f.prototype = parent.prototype;

  child.prototype = new f();

  child.prototype.constructor = child;

}

​

var Animal = function () {

  this.selfType = 'self_animal';

};

Animal.prototype.type = 'animal';

Animal.prototype.getType = function () {

  return this.type;

};

Animal.prototype.getName = function () {

  return 'My name is ' + this.name;

};

​

var Turtle = function () {

};

​

extend(Turtle, Animal);

​

var NinjaTurtle = function (name) {

  this.name = name;

};

extend(NinjaTurtle, Turtle);

​

​

var donatello = new NinjaTurtle('Donatello');

​

​

consol = {

  log: function (msg) {

    document.querySelector('div.consol').innerHTML += '<br>' + msg;

  }

};

​

consol.log(donatello.getType());

consol.log(donatello.type);

consol.log(donatello.selfType);

consol.log(donatello.name);

consol.log(donatello.getName());