Object.create

if (typeof Object.create != 'function') Object.create = (function() {
  function Subclass() {}
  function create(object) {
    var result;
    if (!(typeof object == 'object' && object && arguments.length == 1)) throw new TypeError();
    Subclass.prototype = object;
    result = new Subclass();
    Subclass.prototype = null;
    return result;
  }
  return create;
}());