Javascript augmentation pattern for a factory method

augment.js

// This augmentation style is appropriate for a factory-style function,
// which might be something that was imported as part of a library.
var factory = function factory() {
  var data = [];
  
  // Return an object with one or more methods.
  return {
    
    init: function() {
      data.push.apply(data, arguments);
      return this;
    },
    
    items: function() {
      return data.slice(0, data.length);
    }
  };
};

// This pattern augments  the factory function, such that whenever
// the factory function is called, it has the augmented method(s).
factory = (function(obj) {
  return function() {
    var o = obj();
    o.toString = function() {
      return this.items().toString();
    };
    return o;
  };
})(factory);