The library for web and native user interfaces.
React is a JavaScript library for building user interfaces with a declarative, component-based approach. The repository is organized as a monorepo containing both the core React library and the React Compiler, an active project that automatically optimizes React components through memoization. The compiler is implemented in JavaScript using a multi-phase pipeline that constructs a high-level intermediate representation (HIR) of the code, performs type and effect inference, builds reactive scopes, and generates optimized output. Active development includes a Rust port of the compiler infrastructure, with code and planning documentation located in dedicated directories within the compiler subdirectory.