react▌

Comprehensive React component testing with Jest and React Testing Library covering configuration, mocking, async patterns, and best practices. \n \n Covers Jest configuration for JavaScript and TypeScript projects, including setup files, module mapping, and coverage thresholds \n Provides query strategies prioritizing accessibility (getByRole, getByLabelText) and explains getBy, queryBy, and findBy variants \n Includes mocking patterns for modules, functions, API calls via MSW, context, and chil

Prescriptive workflow for incremental adoption of React Native in existing native apps using @callstack/react-native-brownfield, from initial setup through phased host integration.

Authentication for React SPAs using Auth0 Universal Login with redirect-based flows. \n \n Supports React 16–19 with Vite or Create React App; wraps your app with Auth0Provider and exposes hooks like useAuth0() , loginWithRedirect() , and logout() \n Handles user sessions, access tokens, and profile data automatically; SDK manages secure token storage without manual localStorage handling \n Includes protected routes, API token injection, and error handling patterns documented in the integration

Core React patterns for component design, state management, and optimization.

Modern React patterns and best practices for production applications. \n \n Covers component design principles, hook extraction patterns, and state management selection across complexity levels from simple useState to global stores like Zustand and Redux Toolkit \n Includes React 19 patterns with new hooks (useActionState, useOptimistic, use) and compiler benefits for automatic memoization \n Provides composition patterns including compound components, render props vs hooks trade-offs, and highe

45 performance optimization rules for React and Next.js, organized by impact from critical waterfalls and bundle size down to advanced patterns. \n \n Covers 8 rule categories prioritized by performance impact: eliminating waterfalls, bundle optimization, server-side performance, client-side data fetching, re-render optimization, rendering performance, JavaScript performance, and advanced patterns \n Each rule includes explanations, incorrect/correct code examples, and context to guide automated

Essential React Hooks for sensors, UI, animations, side-effects, lifecycles, and state management. \n \n 30+ sensor hooks track browser APIs and device interfaces including geolocation, keyboard input, scroll position, network state, and device motion \n 9 UI hooks manage audio, video, fullscreen, drag-and-drop, speech synthesis, and click-away detection \n 8 animation hooks provide requestAnimationFrame loops, intervals, timeouts, spring dynamics, and tweening \n 16 side-effect hooks handle asy

Modern React UI patterns for loading states, error handling, and data fetching. \n \n Covers five core principles: never show stale UI, always surface errors, use optimistic updates, progressive disclosure, and graceful degradation \n Provides decision trees and component patterns for loading indicators, skeleton screens, error states, empty states, and button submission handling \n Includes critical anti-patterns to avoid, such as showing spinners when cached data exists, silently swallowing er

Exhaustive React API research from authoritative sources, not training knowledge. \n \n Spawns six parallel research agents to systematically search React's test files, source code, git history, PRs, issues, and type definitions \n Enforces skepticism mandate: treats source material as sole authority and flags discrepancies between findings and common understanding \n Generates documented research with exact file paths, line numbers, and source links for every claim, code example, and warning \n

Convert JSON specs into React component trees with type-safe props and state management. \n \n Define catalogs with Zod schemas for component props, then implement components with automatic type safety and validation \n Built-in state management via StateProvider with two-way binding ( $bindState ), conditional rendering, and external store integration (Redux, Zustand, XState) \n Event system with action dispatching, state watchers, and four built-in actions (setState, pushState, removeState, va