This comprehensive guide outlines best practices, conventions, and standards for development with modern web technologies including ReactJS, NextJS, Redux, TypeScript, JavaScript, HTML, CSS, and UI frameworks. Development Philosophy - Write clean, maintainable, and scalable code - Follow SOLID principles - Prefer functional and declarative programming patterns over imperative - Emphasize type safety and static analysis - Practice component-driven development Code Implementation Guidelines Planning Phase - Begin with step-by-step planning - Write detailed pseudocode before implementation - Document component architecture and data flow - Consider edge cases and error scenarios Code Style - Use tabs for indentation - Use single quotes for strings (except to avoid escaping) - Omit semicolons (unless required for disambiguation) - Eliminate unused variables - Add space after keywords - Add space before function declaration parentheses - Always use strict equality (===) instead of loose equality (==) - Space infix operators - Add space after commas - Keep else statements on the same line as closing curly braces - Use curly braces for multi-line if statements - Always handle error parameters in callbacks - Limit line length to 80 characters - Use trailing commas in multiline object/array literals Naming Conventions General Rules - Use PascalCase for: - Components - Type definitions - Interfaces - Use kebab-case for: - Directory names (e.g., components/auth-wizard) - File names (e.g., user-profile.tsx) - Use camelCase for: - Variables - Functions - Methods - Hooks - Properties - Props - Use UPPERCASE for: - Environment variables - Constants - Global configurations Specific Naming Patterns - Prefix event handlers with 'handle': handleClick, handleSubmit - Prefix boolean variables with verbs: isLoading, hasError, canSubmit - Prefix custom hooks with 'use': useAuth, useForm - Use complete words over abbreviations except for: - err (error) - req (request) - res (response) - props (properties) - ref (reference) React Best Practices Component Architecture - Use functional components with TypeScript interfaces - Define components using the function keyword - Extract reusable logic into custom hooks - Implement proper component composition - Use React.memo() strategically for performance - Implement proper cleanup in useEffect hooks React Performance Optimization - Use useCallback for memoizing callback functions - Implement useMemo for expensive computations - Avoid inline function definitions in JSX - Implement code splitting using dynamic imports - Implement proper key props in lists (avoid using index as key) Next.js Best Practices Core Concepts - Utilize App Router for routing - Implement proper metadata management - Use proper caching strategies - Implement proper error boundaries Components and Features - Use Next.js built-in components: - Image component for optimized images - Link component for client-side navigation - Script component for external scripts - Head component for metadata - Implement proper loading states - Use proper data fetching methods Server Components - Default to Server Components - Use URL query parameters for data fetching and server state management - Use 'use client' directive only when necessary: - Event listeners - Browser APIs - State management - Client-side-only libraries TypeScript Implementation - Enable strict mode - Define clear interfaces for component props, state, and Redux state structure. - Use type guards to handle potential undefined or null values safely. - Apply generics to functions, actions, and slices where type flexibility is needed. - Utilize TypeScript utility types (Partial, Pick, Omit) for cleaner and reusable code. - Prefer interface over type for defining object structures, especially when extending. - Use mapped types for creating variations of existing types dynamically. UI and Styling Component Libraries - Use Shadcn UI for consistent, accessible component design. - Integrate Radix UI primitives for customizable, accessible UI elements. - Apply composition patterns to create modular, reusable components. Styling Guidelines - Use Tailwind CSS for styling - Use Tailwind CSS for utility-first, maintainable styling. - Design with mobile-first, responsive principles for flexibility across devices. - Implement dark mode using CSS variables or Tailwind’s dark mode features. - Ensure color contrast ratios meet accessibility standards for readability. - Maintain consistent spacing values to establish visual harmony. - Define CSS variables for theme colors and spacing to support easy theming and maintainability. State Management Local State - Use useState for component-level state - Implement useReducer for complex state - Use useContext for shared state - Implement proper state initialization Global State - Use Redux Toolkit for global state - Use createSlice to define state, reducers, and actions together. - Avoid using createReducer and createAction unless necessary. - Normalize state structure to avoid deeply nested data. - Use selectors to encapsulate state access. - Avoid large, all-encompassing slices; separate concerns by feature. Error Handling and Validation Form Validation - Use Zod for schema validation - Implement proper error messages - Use proper form libraries (e.g., React Hook Form) Error Boundaries - Use error boundaries to catch and handle errors in React component trees gracefully. - Log caught errors to an external service (e.g., Sentry) for tracking and debugging. - Design user-friendly fallback UIs to display when errors occur, keeping users informed without breaking the app. Testing Unit Testing - Write thorough unit tests to validate individual functions and components. - Use Jest and React Testing Library for reliable and efficient testing of React components. - Follow patterns like Arrange-Act-Assert to ensure clarity and consistency in tests. - Mock external dependencies and API calls to isolate unit tests. Integration Testing - Focus on user workflows to ensure app functionality. - Set up and tear down test environments properly to maintain test independence. - Use snapshot testing selectively to catch unintended UI changes without over-relying on it. - Leverage testing utilities (e.g., screen in RTL) for cleaner and more readable tests. Accessibility (a11y) Core Requirements - Use semantic HTML for meaningful structure. - Apply accurate ARIA attributes where needed. - Ensure full keyboard navigation support. - Manage focus order and visibility effectively. - Maintain accessible color contrast ratios. - Follow a logical heading hierarchy. - Make all interactive elements accessible. - Provide clear and accessible error feedback. Security - Implement input sanitization to prevent XSS attacks. - Use DOMPurify for sanitizing HTML content. - Use proper authentication methods. Internationalization (i18n) - Use next-i18next for translations - Implement proper locale detection - Use proper number and date formatting - Implement proper RTL support - Use proper currency formatting Documentation - Use JSDoc for documentation - Document all public functions, classes, methods, and interfaces - Add examples when appropriate - Use complete sentences with proper punctuation - Keep descriptions clear and concise - Use proper markdown formatting - Use proper code blocks - Use proper links - Use proper headings - Use proper lists