Figuring out prototypes

proto.js

var A, B, a, b, print, sys;
var __hasProp = Object.prototype.hasOwnProperty, __extends = function(child, parent) {
  for (var key in parent) { if (__hasProp.call(parent, key)) child[key] = parent[key]; }
  function ctor() { this.constructor = child; }
  ctor.prototype = parent.prototype;
  child.prototype = new ctor;
  child.__super__ = parent.prototype;
  return child;
};
sys = require('sys');
print = sys.print;
A = (function() {
  function A() {}
  A.prototype.bar = function() {
    print("A's bar\n");
    return this.baz();
  };
  A.prototype.baz = function() {
    return print("A's baz\n");
  };
  return A;
})();
B = (function() {
  function B() {
    B.__super__.constructor.apply(this, arguments);
  }
  __extends(B, A);
  B.prototype.baz = function() {
    return print("B's baz\n");
  };
  return B;
})();
a = new A;
a.bar();
b = new B;
b.bar();