JavaScript and React Patterns showcases idiomatic patterns and anti-patterns for building React applications, focusing on readability, performance, and maintainability. It translates fuzzy best practices into concrete examples—how to compose components cleanly, manage state thoughtfully, and avoid foot-guns with effects and memoization. The guidance leans on modern React paradigms like hooks, context, custom hooks, and component composition to replace older, heavier patterns. Performance considerations appear throughout, such as when to memoize, how to minimize re-renders, and where to split components. Each example is concise and focused, making it easy to apply to real codebases without wading through long essays. ...