Not really sure what you mean. Node at least runs fine in emulation mode and it takes like 5 minutes to build node from scratch to run natively on this thing.
Chrome is running great, natively, on M1, so Javascript is running just fine on the V8 engine.
Whats wrong with javascriptcore?
I don't think JavascriptCore is anybody's idea of the "Javascript stack". Parent means Node/NPM/Electron.
Though, I'm pretty sure he's mistaken on its status.