Simple iterator

main.js

    var agg = (function () {

        var index = 0,
            data = [1,2,3,4,5],
            length = data.length;

        return {

            next: function () {

                var element;

                if (!this.hasNext()) {
                    return null;
                }
                element = data[index];
                index = index + 1;
                return element;

            },
            hasNext: function () {
                return index < length;
            }, 
            rewind: function () {
                index = 0;
            }, 
            current: function () {
                return data[index];
            }

        }

    });