Prototypal inheritance in javascript using Object.create with functions getting a "parent" property to be able to call the method they overwrote

object.spawn.js

/**
 * Object.spawn for a more terse form of Object.create,
 * with the super added bonus of giving all overriden
 * functions a "parent" property which refers back to
 * thing it was overriding ... like "parent" or "super"
 * in classical OOP
 * 
 * @link http://howtonode.org/prototypical-inheritance
 * @param  {Object} parent The parent object used in Object.create
 * @param  {Object} props  The object containing properties, unlike Object.create doesn't need an extra level of abstraction, and all properties will be enumerable
 * @return {Object}        The newly created object
 */
Object.spawn = function (parent, props) {
  var defs = {}, key;
  for (key in props) {
    if (props.hasOwnProperty(key)) {
      defs[key] = {
        value: props[key],
        enumerable: true
      };
      // here's the "parent" magic.
      // we make sure that both keys are functions,
      // and the "child" doesn't already have a "parent"
      if (
        typeof props[key] === 'function' &&
        typeof parent[key] === 'function' &&
        typeof props[key].parent === 'undefined'
      ) {
        props[key].parent = parent[key];
      }
    }
  }
  return Object.create(parent, defs);
};



var Base = {
    init: function() {
        console.log('Base.init');
        // n.b. returning "this" from init functions is a nice pattern
        return this;
    }
};

/*
Note that you could have used "arguments.callee" but that doesn't
work in strict mode, so in classic "Things To Do In Denver When
You're Dead" style: give it a name.
*/
var Game = Object.spawn(Base, {
    init: function Game_init() {
        Game_init.parent.apply(this);
        console.log('Game.init');
        return this;
    }
});

var Pong = Object.spawn(Game, {
    init: function Pong_init() {
        Pong_init.parent.apply(this);
        console.log('Pong.init');
        return this;
    }
});


var pong = Object.spawn(Pong).init();
/* Output:
Base.init
Game.init
Pong.init
*/