今日知ったasyncシリーズのやつ

・async.eachSeries
eachSeries(arr, iterator, callback)

The same as each only the iterator is applied to each item in the array in series. The next iterator is only called once the current one has completed processing. This means the iterator functions will complete in order.

arrに対し、非同期処理を含むiteratorを順番に実行させる。