iterator

function iterator(collection) {

    var index = 0;

    var length = collection.length;

    

    function next() {

        var item = collection[index++];

        next.hasNext = index < length;

        return item;

    }

    

    next.hasNext = index < length;

    return next;

}

(function () {

    var collection = [1, 2, 3, 4, 5];

    var next = iterator(collection);

    var result = [];

    while (next.hasNext) {

        result.push(next());

    }

    console.log(collection);

    console.log(result);

}());