The other side of React Native

The wall React Native eventually hits

In the iOS and Android courses you built PawWalk's screens. Almost everything a walker sees — the walker list, the booking form, the live map — React Native can draw with JavaScript. But some things live below JavaScript: the LiDAR sensor on an iPhone, ARKit and ARCore, Bluetooth, the secure enclave. React Native has no JS API for those. When your product needs one, you don't wait for a library — you write the native module yourself.

That single skill — reaching through React Native to a platform capability and handing it back to JS as a clean component — is what separates a mid-level RN developer from a senior one. It's also the thing expo-ui, react-native-maps, and every camera library are made of.

In an interview, say: "React Native is a rendering layer over native UI; when I need a capability JS can't reach — a sensor, an OS SDK — I write an Expo native module that exposes it as a typed component or function. Same machinery the ecosystem's own libraries use."