react/Code Sharing

React's approach to sharing logic across components has gone through real evolution. Mixins (deprecated early on) let you merge behavior into a component but caused implicit dependencies and naming collisions that made components fragile and hard to reason about. Higher-Order Components and render props both solved this more explicitly, by wrapping a component or passing a render function — but both added extra components to the tree just to share logic.

Hooks became the default because they solve the same problem — sharing logic across components — without wrapping anything or adding to the component tree at all; a custom hook is just a function. That said, HOCs and render props haven't disappeared: plenty of libraries (routing, state management) still expose HOC-style APIs like connect() for backward compatibility or specific composition needs, so recognizing all three patterns still matters when reading real codebases.