A front-end JavaScript library for building user interfaces

A back-end framework for handling server requests

A database for managing data storage

A programming language for writing server-side code

What will be the output of the following code? JavaScript import React, { useState } from 'react'; function App() { const [count, setCount] = useState(0); return ( <div> <h1>{count}</h1> <button onClick={() => setCount(count + 1)}>Increment</button> </div> ); } export default App;

The counter will increment by 1 each time.

The counter will increment by 2 each time.

The counter will stay the same.

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Introduction to React

Here we will cover all the basic concepts of React like JSX, Virtual Dom, Components and much more.

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Question 1

What is React?

A front-end JavaScript library for building user interfaces
A back-end framework for handling server requests
A database for managing data storage
A programming language for writing server-side code

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Question 2

What is the purpose of the Virtual DOM in React?

It improves server performance.
It provides a faster way to update the user interface.
It helps in routing between pages.
It is used for managing application state.

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Question 3

Which of the following correctly describes JSX?

A templating engine for React
A syntax extension for JavaScript
A CSS preprocessor used in React
A database query language

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Question 4

Which command is used to create a new React app using Create React App?

npx react-init
npx create-react-app my-app
npm install react
react create my-app

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Question 5

What file is the entry point for a React application?

app.js
index.html
index.js
react.js

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Question 6

What is a React component?

A reusable piece of code that returns JSX
A JavaScript variable
A function to connect React with the backend
A tool for compiling JSX

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Question 7

What is the purpose of the ReactDOM.render method?

To manage application state
To compile JSX into JavaScript
To render a React component into the DOM
To define the Virtual DOM

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Question 8

Which of the following statements about the Virtual DOM is true?

It is the actual DOM manipulated directly by React components.
It is a programming interface for web documents
It is a lightweight, in-memory representation of the actual DOM.
It is used primarily for rendering static content in React applications.

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Question 9

What will be the output of the following code?

JavaScript

import React, { useState } from 'react';
function App() {
    const [count, setCount] = useState(0);
    return (
        <div>
            <h1>{count}</h1>
            <button onClick={() => setCount(count + 1)}>Increment</button>
        </div>
    );
}
export default App;

The counter will increment by 2 each time.
The counter will increment by 1 each time.
The counter will stay the same.
The code will throw an error.

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Question 10

What will be the output of this React code?

JavaScript

import React from 'react';
import ReactDOM from 'react-dom';
function App() {
    const greeting = "Hello";
    return <h1>{greeting} World</h1>;
}
ReactDOM.render(<App />, document.getElementById('root'));

Hello World
{greeting} World
"Hello World"
Error

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ReactJS

React Quiz

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