クラスメソッド版iterator

iterator.js

(function() {
  var _Iterator = function() {
    var that = this;
    return function(items) {
      if (!items.length) throw new TypeError(typeof items + ' is not permitted.');
      that._items = (items instanceof Array) ? items.slice() : Array.prototype.slice.call(items);
      that._limit = that._items.length;
      that._item;
      return that;
    };
  };
  _Iterator.prototype = {
    _move: function(method) {
      this._item = this._items[method]();
      this._limit--;
      if (this._limit === -1) throw new Error('Stop Iteration');
      return this;
    },
    next: function() {
      return this._move('shift');
    },
    prev: function() {
      return this._move('pop');
    },
    get: function(callback) {
      if (typeof callback === 'function') {
        callback(this._item);
        return this;
      }
      else return this._item;
    }
  };
  window.Iterator = new _Iterator();
})();

Iterator([1,2,3]).next().get(console.log).prev().get(console.log).next().get();