JavaScript Interface (JSI)

• JSI is an interface that allows JavaScript to hold a reference to a C++ object and vice-versa.
• With a memory reference, you can directly invoke methods without serialization costs.

Fabric

• Fabric is React Native's new rendering system, a conceptual evolution of the legacy render system.
• The core principles are to unify more render logic in C++, improve interoperability with host platforms, and to unlock new capabilities for React Native.