gistfile1.js

var Animal, Horse, Snake, sam, tom;
var __extends = function(child, parent) {
  var ctor = function(){ };
  ctor.prototype = parent.prototype;
  child.__superClass__ = parent.prototype;
  child.prototype = new ctor();
  child.prototype.constructor = child;
};
Animal = function() {  };
Animal.prototype.move = function(meters) {
  return alert(this.name + " moved " + meters + "m.");
};

Snake = function(name) {
  this.name = name;
  return this;
};
__extends(Snake, Animal);
Snake.prototype.move = function() {
  alert("Slithering...");
  return Snake.__superClass__.move.call(this, 5);
};

Horse = function(name) {
  this.name = name;
  return this;
};
__extends(Horse, Animal);
Horse.prototype.move = function() {
  alert("Galloping...");
  return Horse.__superClass__.move.call(this, 45);
};

sam = new Snake("Sammy the Python");
tom = new Horse("Tommy the Palomino");
sam.move();
tom.move();