Reference Link:
TDZ(temporal dead zone)
TDZ https://www.stridenyc.com/blog/what-is-the-temporal-dead-zone https://stackoverflow.com/questions/33198849/what-is-the-temporal-dead-zone https://ja.stackoverflow.com/questions/21992/let%E3%81%A7%E3%81%AE%E5%A4%89%E6%95%B0%E5%AE%A3%E8%A8%80%E3%81%A7%E3%81%AF%E5%B7%BB%E3%81%8D%E4%B8%8A%E3%81%92%E3%81%8C%E8%A1%8C%E3%82%8F%E3%82%8C%E3%81%AA%E3%81%84