React Concepts Overview

Introduction

• React is a JavaScript library with terms like reconciliation, composition, and error boundaries.

Components

• Definition: Building blocks of React apps (similar to Legos).
• Functionality: Each component is a JavaScript function that returns markup.
• JSX: Instead of HTML, React uses JSX (JavaScript in Disguise).
  • JSX allows dynamic values and attributes in camel case (e.g., className instead of class).
• Single Parent Element: A component must return one parent element; use a React Fragment to avoid extra elements.

Props

• Definition: Props (properties) allow passing data to components.
  • To use, create a prop attribute on the component and access it via the component's parameters.
• Children Prop: Allows passing other components between opening and closing tags.
  • Useful for composition and creating layout components.
• Key Prop: Unique identifier for components in lists (usually from the map function).

Rendering Process

• Rendering: React uses the virtual DOM (vDOM) to efficiently update the browser DOM.
  • Diffing: Compares updated vDOM with previous version to identify changes.
  • Reconciliation: Updates the real DOM based on identified changes.

Event Handling

• React has built-in events (e.g., onClick, onChange, onSubmit).
• Use event handlers to respond to user interactions (e.g., showing an alert on button click).

State Management

• Definition: State is a snapshot of the app at a given time.
• useState Hook: Manages state in functional components.
  • Returns an array: the state variable and an update function.
• Controlled Components: Input values controlled by state for more predictable behavior.

React Hooks

• Types of Hooks:
  • State Hooks: useState, useReducer for managing state.
  • Context Hooks: useContext for passing data through the app.
  • Ref Hooks: useRef for referencing HTML elements.
  • Effect Hooks: useEffect for side effects like API calls.
  • Performance Hooks: useMemo, useCallback for optimization.

Component Purity

• Purity: Pure React components return the same output for the same input.
• Strict Mode: Component to catch potential issues during development.

Effects and Refs

• Effects: Code that interacts with external systems or APIs (e.g., HTTP requests).
• Refs: Reference actual DOM elements via useRef and the ref prop.

Context and Portals

• Context: Allows sharing data through the component tree without prop drilling.
• Portals: Render components outside their parent hierarchy, useful for modals, tooltips, etc.

Suspense and Error Boundaries

• Suspense: Manages loading states and fallback components while fetching data.
• Error Boundaries: Catch app-breaking errors and display fallback UI for users.

Conclusion

• Comprehensive understanding of React concepts essential for building applications.
• Consider joining a boot camp for in-depth learning.