Simple extendable classes in javascript

class.js

/* This WAS a two-line function until an awesome reddit user pointed out my logical flaw. Now It's a 5-line function :( */

var Class = function(d){
  d.constructor.extend = function(def){
    for (var k in d) if (!def.hasOwnProperty(k)) def[k] = d[k];
    return Class(def);
  };
  return (d.constructor.prototype = d).constructor;
};

var Node = Class({
  constructor: function(n, w){
    this.neighbors = n || [];
    this.weights = w || [];
    return this;
  }
, addNeighbor: function(neighbor, weight){
    neighbor.neighbors.push(this);
    neighbor.weights.push(weight);
    this.neighbors.push(neighbor);
    this.weights.push(weight);
    return this;
  }
});

var Nooode = Node.extend({
  constructor: function(n, w){
    this.neighbors = n || [];
    this.weights = w || [];
    this.poop = "lakjsdflkjaskdflajsdlf";
    return this;
  }
});

var myNode = new Node();
myNode.addNeighbor(new Node(), 5);
var myNooode = new Nooode();
myNooode.addNeighbor(myNode, 2);​