https://firebase.googleblog.com/2017/06/keep-your-promises-when-using-cloud.html?fbclid=IwAR2FuvlU2CbwjV-I75q7-WIkJyLHRYT-R3cyleEUWF3Fsq42THMCwZN6by8
const ref_p1_state = root.child(`player_states/${game_state.p1uid}`) const ref_p2_state = root.child(`player_states/${game_state.p2uid}`) const pr_update_p1 = ref_p1_state.update(update_p1) const pr_update_p2 = ref_p2_state.update(update_p2) return Promise.all([pr_update_p1, pr_update_p2]) ==========
https://stackoverflow.com/questions/55430079/promise-all-does-not-wait-for-firestore-query-to-loop
使用 https://github.com/dalenguyen/firestore-backup-restore
base on https://github.com/dalenguyen/firestore-import-export
能處理timestamp
