React Documentation

This guide introduces React programming theory, focusing on concepts and best practices for developers using the Codeunia Learn platform.

Overview

React is a JavaScript library for building user interfaces, particularly single-page applications. It uses a component-based architecture and virtual DOM for efficient rendering. Developed by Facebook, React emphasizes declarative programming and reusability.

React Fundamentals

Components

Components are the building blocks of React apps. They can be functional or class-based. Functional components use hooks for state and lifecycle.

JSX

JSX is a syntax extension allowing HTML-like code in JavaScript. It compiles to React.createElement calls.

Props

Props pass data from parent to child components. They are immutable.

State

State manages component data that changes over time. Use useState hook in functional components.

Hooks

Hooks like useEffect, useContext, useReducer manage side effects, context, and complex state.

Lifecycle Methods

Class components use methods like componentDidMount. Functional components use useEffect.

Event Handling

Events are handled with camelCase syntax (e.g., onClick). Event handlers are functions.

Conditional Rendering

Use conditional operators or logical && for dynamic content.

Lists and Keys

Render lists with map(). Keys help React identify changes.

Forms

Controlled components manage form state. Libraries like Formik simplify complex forms.

Context API

Context provides global state without prop drilling.

Best Practices

Keep components small, use functional components with hooks, and optimize with React.memo and useMemo.

Testing

Jest and React Testing Library test components and interactions.

Performance Optimization

Use React.memo, useMemo, useCallback, and lazy loading to optimize renders.

Deployment

Build with Create React App or Vite. Deploy to platforms like Vercel or Netlify.

Resources and References

• React Official Documentation
• React Hooks
• React Router

Troubleshooting

Common issues include infinite loops, prop drilling, and key warnings. Use React DevTools for debugging.

Development Setup

Use Create React App for quick starts. Set up ESLint, Prettier, and version control.