React
Build modern user interfaces
Created
2013 by Meta (Facebook)
Language
JavaScript / TypeScript
Paradigm
Component-based, declarative
Rendering
Virtual DOM (diffing)
Popularity
220k+ GitHub stars
npm downloads
20M+ weekly
Used by
Meta, Netflix, Airbnb, Uber
Best for
Interactive web UIs
What is React?
React is a JavaScript library for building user interfaces, created at Meta in 2013. It's the most widely used frontend library in the industry — powering Facebook, Instagram, Netflix, Airbnb, and millions of other apps.
Why React?
React introduced the idea of component-based architecture: you build UIs from small, reusable, self-contained pieces. It uses a virtual DOM to efficiently update only what changed, rather than re-rendering the entire page.
| Feature | React | Vue | Angular | Svelte |
|---|---|---|---|---|
| Learning curve | Medium | Easy | Hard | Easy |
| Job market | Largest | Growing | Stable | Growing |
| Flexibility | High | Medium | Low (opinionated) | Medium |
| Bundle size | Medium | Small | Large | Smallest |
| Community | Largest | Large | Large | Growing |
Core concepts
- Components — Functions that return JSX (HTML-like syntax in JavaScript).
- Props — Data passed from parent to child (read-only).
- State — Internal data that changes over time, triggering re-renders.
- Effects — Side effects like API calls, timers, and subscriptions.
What you'll learn
| Chapter | What you'll know |
|---|---|
| Setup | Create a project, understand the toolchain |
| Components | JSX, props, conditional rendering |
| State | useState, events, forms |
| Effects | useEffect, API calls, cleanup |
| Lists | Rendering arrays, keys, filtering |
Start with setup to create your first React project.