非同步
https://www.youtube.com/watch?v=GkiWX-0_xAs
https://www.youtube.com/watch?v=i_-mLmaNgHo
https://www.youtube.com/watch?v=IZMtYqpq4dQ
https://www.youtube.com/watch?v=xxGm8JDJ4Gs
上傳作業