Please tell me how listening for changes in the database on the web works

[bombicod]

It can be seen from your example that the data is automatically updated in different browser tabs. How does it work? (Because indexdb can't do that.) Thank you

[alextekartik]

I have added some doc here: https://github.com/tekartik/sembast.dart/blob/master/sembast_web/doc/implementation_details.md

Storage format

Indexed DB

A sembast database is stored in one Indexed DB database that acts a journal database.
Like sembast, the whole database is loaded into memory from indexedDB.

The journal database allow building a consistent database at any time even across tabs.

Synchronization between tabs

The journal database has a global auto-incremental revision number that is incremented for each change
(one increment per transaction).

Sembast uses web LocalStorage to store the lastest revision number of the database.

It also registers for LocalStorage changes to be notified when another tab makes some changes.
It then compares its current revision number vs the new one and reload
the new database changes if needed. Only the new/modified records are loaded, making changes across tabs efficient.

[bombicod]

Thank you very much for the detailed answer!