The JavaScript Interface (JSI) is the core of React Native's new architecture. It allows JavaScript to hold a reference to C++ host objects and call methods on them synchronously.
Why JSI?
- Zero Serialization: No more converting data to JSON and back across the bridge.
- Synchronous Execution: Call native code just like a standard JS function.
- Improved Startup: Models can be initialized lazily as needed.
When to Use JSI:
You probably won't need JSI for a standard UI app. But for high-frequency tasks like:
- Real-time video processing.
- Complex physics engines.
- Heavy cryptography.
- Deep, low-latency Bluetooth communication.
JSI is where React Native truly bridges the gap with purely native Swift or Kotlin apps.