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What is React?

5 min read Quiz at the end

React is a JavaScript library for building user interfaces with reusable components. It uses a virtual DOM to efficiently update only what changed on screen. Created by Meta, it is the most popular frontend library today.

What is React?

React is a JavaScript library for building user interfaces. Created by Facebook (Meta) in 2013, it uses a component-based architecture and a virtual DOM for efficient UI updates.

Component-based — UI split into reusable pieces
Declarative — describe what you want, React handles how
Virtual DOM — efficient diffing and updating
Huge ecosystem — Next.js, React Native, React Router

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Topic Quiz · 5 questions

Test your understanding before moving on

1. Who created React?

💡 React was created by Facebook (Meta) and open-sourced in 2013.

2. What is the virtual DOM?

💡 React maintains a virtual DOM to efficiently calculate the minimum DOM updates needed.

3. What does "declarative" mean in React?

💡 Declarative means you describe the desired UI state and React handles the updates.

4. React is a ___

💡 React is a JavaScript library for building user interfaces — not a full framework.

5. What language extension does React use?

💡 JSX (JavaScript XML) lets you write HTML-like syntax in JavaScript files.

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What is React?

What is React?

Test your understanding before moving on