JavaScriptIndexedDB

Remarks

Transactions

Transactions need to be used immediately after they're created. If they aren't used in the current event loop (basically before we wait for anything like a web request) they'll go into an inactive state where you can't use them.

Databases can only have one transaction that writes to a particular object store at a time. So you can have as many as you want that read from our things store, but only one can make changes at any given time.