async.eachSeries Sample

gistfile1.js

 async.eachSeries = function (arr, iterator, callback) {
    callback = callback || function () {};
    if (!arr.length) {
        return callback();
    }
    var completed = 0;
    var iterate = function () {
        iterator(arr[completed], function (err) {
            if (err) {
                callback(err);
                callback = function () {};
            }
            else {
                completed += 1;
                if (completed >= arr.length) {
                    callback(null);
                }
                else {
                    iterate();
                }
            }
        });
    };
    iterate();
};