React Best Practices

React Best Practices

Skill Profile

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• DevOps
• Backend
• Frontend
• AI-RAG
• Security Critical

Overview

React is a JavaScript library for building user interfaces using component-based architecture and virtual DOM for optimal performance. React 18+ introduces features including functional components with hooks, custom hooks for reusable logic, Context API for global state, Suspense for async rendering, and concurrent features for improved performance. Following best practices ensures maintainable, testable, and performant React applications.

Why This Matters

• Reduces Development Time: Component reuse and hooks reduce development time
• Increases Maintainability: Organized code reduces maintenance costs
• Improves Performance: Virtual DOM and optimizations enhance performance
• Enhances User Experience: Fast rendering and smooth interactions
• Improves Code Quality: TypeScript and patterns enhance code quality

Core Concepts & Rules

1. Core Principles

• Follow established patterns and conventions
• Maintain consistency across codebase
• Document decisions and trade-offs

2. Implementation Guidelines

• Start with the simplest viable solution
• Iterate based on feedback and requirements
• Test thoroughly before deployment

Inputs / Outputs / Contracts

• Inputs:
  • Component requirements
  • State management needs
  • Performance requirements
  • Accessibility guidelines
• Entry Conditions:
  • React 16+ is available
  • TypeScript is configured
  • Testing framework is set up
  • Performance baseline is measured
• Outputs:
  • Functional React components
  • Custom hooks for reusable logic
  • State management strategy
  • Performance-optimized code
• Artifacts Required (Deliverables):
  • Component library
  • Custom hooks
  • State management setup
  • Test suite
• Acceptance Evidence:
  • Components render correctly
  • State management works
  • Performance targets met
  • Tests pass
• Success Criteria:
  • Components are reusable and composable
  • State is managed correctly
  • Performance is optimized
  • Code is maintainable

Skill Composition

• Depends on: typescript-standards
• Compatible with: nextjs-patterns, shadcn-ui, form-handling
• Conflicts with: None
• Related Skills: state-management, error-boundaries-react

Quick Start / Implementation Example

1. Review requirements and constraints
2. Set up development environment
3. Implement core functionality following patterns
4. Write tests for critical paths
5. Run tests and fix issues
6. Document any deviations or decisions

# Example implementation following best practices
def example_function():
    # Your implementation here
    pass

Assumptions / Constraints / Non-goals

• Assumptions:
  • Development environment is properly configured
  • Required dependencies are available
  • Team has basic understanding of domain
• Constraints:
  • Must follow existing codebase conventions
  • Time and resource limitations
  • Compatibility requirements
• Non-goals:
  • This skill does not cover edge cases outside scope
  • Not a replacement for formal training

Compatibility & Prerequisites

• Supported Versions:
  • Python 3.8+
  • Node.js 16+
  • Modern browsers (Chrome, Firefox, Safari, Edge)
• Required AI Tools:
  • Code editor (VS Code recommended)
  • Testing framework appropriate for language
  • Version control (Git)
• Dependencies:
  • Language-specific package manager
  • Build tools
  • Testing libraries
• Environment Setup:
  • .env.example keys: API_KEY, DATABASE_URL (no values)

Test Scenario Matrix (QA Strategy)

Technical Guardrails & Security Threat Model

1. Security & Privacy (Threat Model)

• Top Threats: Injection attacks, authentication bypass, data exposure

• Data Handling: Sanitize all user inputs to prevent Injection attacks. Never log raw PII
• Secrets Management: No hardcoded API keys. Use Env Vars/Secrets Manager
• Authorization: Validate user permissions before state changes

2. Performance & Resources

• Execution Efficiency: Consider time complexity for algorithms
• Memory Management: Use streams/pagination for large data
• Resource Cleanup: Close DB connections/file handlers in finally blocks

3. Architecture & Scalability

• Design Pattern: Follow SOLID principles, use Dependency Injection
• Modularity: Decouple logic from UI/Frameworks

4. Observability & Reliability

• Logging Standards: Structured JSON, include trace IDs request_id
• Metrics: Track error_rate, latency, queue_depth
• Error Handling: Standardized error codes, no bare except
• Observability Artifacts:
  • Log Fields: timestamp, level, message, request_id
  • Metrics: request_count, error_count, response_time
  • Dashboards/Alerts: High Error Rate > 5%

Agent Directives & Error Recovery

(ข้อกำหนดสำหรับ AI Agent ในการคิดและแก้ปัญหาเมื่อเกิดข้อผิดพลาด)

• Thinking Process: Analyze root cause before fixing. Do not brute-force.
• Fallback Strategy: Stop after 3 failed test attempts. Output root cause and ask for human intervention/clarification.
• Self-Review: Check against Guardrails & Anti-patterns before finalizing.
• Output Constraints: Output ONLY the modified code block. Do not explain unless asked.

Definition of Done (DoD) Checklist

• Tests passed + coverage met
• Lint/Typecheck passed
• Logging/Metrics/Trace implemented
• Security checks passed
• Documentation/Changelog updated
• Accessibility/Performance requirements met (if frontend)

Anti-patterns / Pitfalls

• ⛔ Don't: Log PII, catch-all exception, N+1 queries
• ⚠️ Watch out for: Common symptoms and quick fixes
• 💡 Instead: Use proper error handling, pagination, and logging

Reference Links & Examples

• Internal documentation and examples
• Official documentation and best practices
• Community resources and discussions

Versioning & Changelog

• Version: 1.0.0
• Changelog:
  • 2026-02-22: Initial version with complete template structure

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