Optional ReadonlyjournalA synchronous store the writes still pending are copied to when the page
goes away, and read back by the next load, because an asynchronous
write started as a page closes may never land. Without one, those writes
are lost with the page.
Hear each write that lands: this store's own, and those of any other store over the same database in another tab. Returns the call that stops listening.
A store whose calls settle later, as IndexedDB's do. The widget reads a namespace from it once (
entries) and answers every later read from that copy, so its own reads stay synchronous; writes follow behind. Having anentriesmethod is what marks a store as asynchronous.