react-best-practices

name react-best-practices description React performance optimization guidelines. This skill should be used when writing, reviewing, or refactoring React code to ensure optimal performance patterns. Triggers on tasks involving React components, data fetching, bundle optimization, or performance improvements. license MIT metadata {"author":"vercel-labs","version":"1.0.0"} React Best Practices Comprehensive performance optimization guide for React applications. Contains 47 rules across 7 categories, prioritized by impact to guide automated refactoring and code generation. Next.js-specific rules have been removed for this project (Electron + Vite + React 19). Originally from vercel-labs/agent-skills (MIT). When to Apply Reference these guidelines when: Writing new React components Implementing data fetching (client-side) Reviewing code for performance issues Refactoring existing React code Optimizing bundle size or load times Rule Categories by Priority Priority Category Impact Prefix 1 Eliminating Waterfalls CRITICAL async- 2 Bundle Size Optimization CRITICAL bundle- 3 Client-Side Data Fetching MEDIUM-HIGH client- 4 Re-render Optimization MEDIUM rerender- 5 Rendering Performance MEDIUM rendering- 6 JavaScript Performance LOW-MEDIUM js- 7 Advanced Patterns LOW advanced- Quick Reference 1. Eliminating Waterfalls (CRITICAL) async-defer-await - Move await into branches where actually used async-parallel - Use Promise.all() for independent operations async-dependencies - Use better-all for partial dependencies async-api-routes - Start promises early, await late in API routes 2. Bundle Size Optimization (CRITICAL) bundle-barrel-imports - Import directly, avoid barrel files bundle-conditional - Load modules only when feature is activated bundle-preload - Preload on hover/focus for perceived speed 3. Client-Side Data Fetching (MEDIUM-HIGH) client-swr-dedup - Use SWR for automatic request deduplication client-event-listeners - Deduplicate global event listeners client-passive-event-listeners - Use passive listeners for scroll client-localstorage-schema - Version and minimize localStorage data 4. Re-render Optimization (MEDIUM) rerender-defer-reads - Don't subscribe to state only used in callbacks rerender-memo - Extract expensive work into memoized components rerender-memo-with-default-value - Hoist default non-primitive props rerender-dependencies - Use primitive dependencies in effects rerender-derived-state - Subscribe to derived booleans, not raw values rerender-derived-state-no-effect - Derive state during render, not effects rerender-functional-setstate - Use functional setState for stable callbacks rerender-lazy-state-init - Pass function to useState for expensive values rerender-simple-expression-in-memo - Avoid memo for simple primitives rerender-move-effect-to-event - Put interaction logic in event handlers rerender-transitions - Use startTransition for non-urgent updates rerender-use-ref-transient-values - Use refs for transient frequent values 5. Rendering Performance (MEDIUM) rendering-animate-svg-wrapper - Animate div wrapper, not SVG element rendering-content-visibility - Use content-visibility for long lists rendering-hoist-jsx - Extract static JSX outside components rendering-svg-precision - Reduce SVG coordinate precision rendering-hydration-no-flicker - Use inline script for client-only data rendering-hydration-suppress-warning - Suppress expected mismatches rendering-activity - Use Activity component for show/hide rendering-conditional-render - Use ternary, not && for conditionals rendering-usetransition-loading - Prefer useTransition for loading state 6. JavaScript Performance (LOW-MEDIUM) js-batch-dom-css - Group CSS changes via classes or cssText js-index-maps - Build Map for repeated lookups js-cache-property-access - Cache object properties in loops js-cache-function-results - Cache function results in module-level Map js-cache-storage - Cache localStorage/sessionStorage reads js-combine-iterations - Combine multiple filter/map into one loop js-length-check-first - Check array length before expensive comparison js-early-exit - Return early from functions js-hoist-regexp - Hoist RegExp creation outside loops js-min-max-loop - Use loop for min/max instead of sort js-set-map-lookups - Use Set/Map for O(1) lookups js-tosorted-immutable - Use toSorted() for immutability 7. Advanced Patterns (LOW) advanced-event-handler-refs - Store event handlers in refs advanced-init-once - Initialize app once per app load advanced-use-latest - useLatest for stable callback refs How to Use Read individual rule files for detailed explanations and code examples: rules/async-parallel.md rules/bundle-barrel-imports.md Each rule file contains: Brief explanation of why it matters Incorrect code example with explanation Correct code example with explanation Additional context and references Full Compiled Document For the complete guide with all rules expanded: AGENTS.md