Support non-hermes JavaScript engine on React Native

[ramakula]

How can I add break points and debug like we do with Chrome? Everytime I press cmd+D and select debug, my app is opening http://localhost:8081/debugger-ui/ in chrome instead of giving me an option to do same in flipper. I have flipper open all the time. Or is it not possible to load sourceMap in flipper and debug?
Appreciate all the help
Chrome connecting and loading source code on debug

I can't seem to get this in flipper. It used to work really well in react native debugger also

[ramakula]

I figured debugging is only supported if Hermes is enabled. Would've been great if regular debugger is integrated as well. Or if there is a plugin, please point me to it

[mweststrate]

@ramakula, the build in debugger is indeed only supported on the Hermes engine at this point.

No idea how hard it is to support non-hermes, it might be that it is pretty doable by taking inspiration from the current plugin which is quite straight forward, so any PRs are welcome!

[mweststrate]

Closing as this is not further actionable for us, but more a React Native limitation

[matgardon]

Hi, I had a hard time finding this information, shouldn't it be more documented in the docs ?

Indeed, flipper is advertised as the future of RN debugging since 0.62, but is not yet mentioned in the docs for RN or Expo.

In the mean time, Hermes is still very much opt-in (pending 0.64 & it's availability on ios ?) and I would guess a lot of apps are still using JSC, making it a serious barrier to entry for flipper.

On the other hand, more and more libs are using JSI/TurboModules (for example reanimated v2), and for projects using those libs, flipper is the only option for debugging JS code (and as a result, for now, it is only possible to debug JS code on android).

Some of those inconsistencies are discussed here, but in the meantime, a good old entry in the docs listing the limitations like the one reanimated did would surely help !

Or maybe you think this should be documented on the RN docs instead ?