React is the most popular JavaScript library for building user interfaces. Created by Facebook, it powers millions of websites including Instagram, Netflix, and Airbnb. Learning React is one of the best investments for any web developer.
Prerequisites
Before learning React, you should know:
- HTML and CSS basics
- JavaScript fundamentals (ES6+)
- DOM manipulation concepts
Core Concepts
Components
React apps are built with reusable components. Think of them as custom HTML elements:
- Functional components (recommended)
- Class components (legacy)
- Component composition
JSX
JSX lets you write HTML-like syntax in JavaScript. It's not HTML, but it looks similar:
- Use
classNameinstead ofclass - All tags must close
- Embed JavaScript with
{curly braces}
Props
Props pass data from parent to child components. They're read-only:
- Pass any type of data
- One-way data flow
- Destructure for cleaner code
State
State manages data that changes over time:
useStatehook for state management- State updates trigger re-renders
- Keep state minimal
Essential Hooks
useState
Manage component state.
useEffect
Handle side effects (API calls, subscriptions).
useContext
Access context without prop drilling.
useRef
Reference DOM elements or persist values.
useMemo and useCallback
Optimize performance by memoizing values and functions.
Building Projects
- Todo App: CRUD operations, state management
- Weather App: API calls, useEffect
- Movie Search: Dynamic data, conditional rendering
- E-commerce Cart: Complex state, context
React Ecosystem
- React Router: Navigation/routing
- Redux/Zustand: Global state management
- React Query: Server state management
- Next.js: Full-stack React framework
Free Learning Resources
- React.dev: Official documentation (excellent)
- freeCodeCamp: Free React course
- Scrimba: Interactive React tutorials
- Full Stack Open: University course
React is the gateway to modern web development. Start with the basics, build projects, and you'll be creating amazing apps in no time!