Support React Native

[bsluther]

When I tried using @tanstack/db in a React Native (Expo) project, I discovered one issue and one potential issue.

1. @tanstack/store says in the docs (https://tanstack.com/store/latest/docs/installation) it doesn't support React Native. I thought I saw this mentioned in the Discord but didn't have time to follow-up and couldn't find that thread.

• I haven't actually "run into" this problem yet, so can't confirm or deny.
• @KyleAMathews mentioned on Discord that @tanstack/db will no longer use @tanstack/store fairly soon, so this might be a non-issue in a coming release.

2. The d2ts package makes use of FinalizationRegistry, which doesn't seem to be supported by React Native yet (see Support FinalizationRegistry in Hermes facebook/hermes#1440).

• This is the actual error I get when trying a minimal usage of TanstackDB, "ReferenceError: Property 'FinalizationRegistry' doesn't exist, js engine: hermes".
• There's a reply in that issue (Support FinalizationRegistry in Hermes facebook/hermes#1440 (comment)) saying FinalizationRegistry can be simulated using WeakRef, which is supported on RN.
• @samwillis mentioned on Discord that FinalizationRegistry is used as an optimization. In the near-term it might be possible to simply disable the optimization when running in RN. Longer-term maybe it's possible to implement a RN friendly optimization, e.g. using WeakRef as mentioned above.

Minimal example here: https://github.com/bsluther/tanstack-db-test

Versions used when I tried this:

"@tanstack/db": "^0.0.5",
"@tanstack/db-collections": "^0.0.7",
"@tanstack/react-db": "^0.0.5",
"expo": "~53.0.11",
"react": "19.0.0",
"react-native": "0.79.3"

[samwillis]

I have opened a PR (electric-sql/d2ts#62) on D2TS to use that polyfill - it's a little difficult to test, I have bodied the vitest config to have --expose-gc but it doesn't seem to trigger, so it's quite hard to confirm that it is working. I think our best bet is to merge and release D2TS using it, update TS DB to use it, then do some manual testing over here. I see know reason it shouldn't work...

[KyleAMathews]

This is fixed

[KyleAMathews]

See https://github.com/KyleAMathews/expo-db-electric-starter for a starter

[gergesh]

I could be wrong here (will dive deeper tomorrow), but is it possible offline transactions broke this again?
I'm seeing calls in the code to window.addEventListener which crash when the addEventListener is undefined on Expo apps.