ES6 classes

es6.js

class Animal {
  constructor(race) {
    this.race = race;
  }
}

class Cat extends Animal {
  constructor(race) {
    super(race);
  }
  say() {
    console.log(this.race + ' says "Meow!"');
  }
}

class Dog extends Animal {
  constructor(race) {
    super(race);
  }
  say() {
    console.log(this.race + ' says "Bark!"');
  }
}

var cat = new Cat('cheshire')
  , dog = new Dog('bulldog')
;

cat.say();
dog.say();

console.log(cat instanceof Cat);
console.log(cat instanceof Dog);
console.log(cat instanceof Animal);
console.log(dog instanceof Animal);

js_compiled.js

'use strict';

var _createClass = (function () { function defineProperties(target, props) { for (var i = 0; i < props.length; i++) { var descriptor = props[i]; descriptor.enumerable = descriptor.enumerable || false; descriptor.configurable = true; if ('value' in descriptor) descriptor.writable = true; Object.defineProperty(target, descriptor.key, descriptor); } } return function (Constructor, protoProps, staticProps) { if (protoProps) defineProperties(Constructor.prototype, protoProps); if (staticProps) defineProperties(Constructor, staticProps); return Constructor; }; })();

var _get = function get(_x, _x2, _x3) { var _again = true; _function: while (_again) { var object = _x, property = _x2, receiver = _x3; desc = parent = getter = undefined; _again = false; if (object === null) object = Function.prototype; var desc = Object.getOwnPropertyDescriptor(object, property); if (desc === undefined) { var parent = Object.getPrototypeOf(object); if (parent === null) { return undefined; } else { _x = parent; _x2 = property; _x3 = receiver; _again = true; continue _function; } } else if ('value' in desc) { return desc.value; } else { var getter = desc.get; if (getter === undefined) { return undefined; } return getter.call(receiver); } } };

function _inherits(subClass, superClass) { if (typeof superClass !== 'function' && superClass !== null) { throw new TypeError('Super expression must either be null or a function, not ' + typeof superClass); } subClass.prototype = Object.create(superClass && superClass.prototype, { constructor: { value: subClass, enumerable: false, writable: true, configurable: true } }); if (superClass) Object.setPrototypeOf ? Object.setPrototypeOf(subClass, superClass) : subClass.__proto__ = superClass; }

function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError('Cannot call a class as a function'); } }

var Animal = function Animal(race) {
  _classCallCheck(this, Animal);

  this.race = race;
};

var Cat = (function (_Animal) {
  _inherits(Cat, _Animal);

  function Cat(race) {
    _classCallCheck(this, Cat);

    _get(Object.getPrototypeOf(Cat.prototype), 'constructor', this).call(this, race);
  }

  _createClass(Cat, [{
    key: 'say',
    value: function say() {
      console.log(this.race + ' says "Meow!"');
    }
  }]);

  return Cat;
})(Animal);

var Dog = (function (_Animal2) {
  _inherits(Dog, _Animal2);

  function Dog(race) {
    _classCallCheck(this, Dog);

    _get(Object.getPrototypeOf(Dog.prototype), 'constructor', this).call(this, race);
  }

  _createClass(Dog, [{
    key: 'say',
    value: function say() {
      console.log(this.race + ' says "Bark!"');
    }
  }]);

  return Dog;
})(Animal);

var cat = new Cat('cheshire'),
    dog = new Dog('bulldog');

cat.say();
dog.say();

console.log(cat instanceof Cat);
console.log(cat instanceof Dog);
console.log(cat instanceof Animal);
console.log(dog instanceof Animal);