React.js Proficiency: A Comprehensive Quiz on Building User Interfaces with React.js.


Top 10:- Questions and Answers for improving and understanding React JS Framework. Learn and Understand React JS Framework like Pro.

1. Question: What is React.js?

Answer: React.js is an open-source JavaScript library for building user interfaces. It is developed and maintained by Facebook.

2. Question: What does JSX stand for in React.js?

Answer: JSX stands for "JavaScript XML." It is a syntax extension that allows you to write HTML-like code in your JavaScript files.

3. Question: What is a component in React.js?

Answer: A component in React.js is a reusable piece of UI that can be composed together to build complex user interfaces.

4. Question: How do you create a functional component in React.js?

Answer: You can create a functional component using a JavaScript function that returns JSX. For example:

function MyComponent() { return <div>Hello, React!</div>; }

5. Question: What is the purpose of state in React.js?

Answer: State in React.js is used to manage data that can change over time and trigger re-rendering of the component when it does.

6. Question: How do you update the state of a component in React.js?

Answer: You can update the state of a component using the setState method. For example: this.setState({ count: this.state.count + 1 });

7. Question: What is a prop in React.js?

Answer: A prop (short for property) is a way to pass data from parent components to child components in React.js.

8. Question: What is the purpose of the virtual DOM in React.js?

Answer: The virtual DOM in React.js is an in-memory representation of the actual DOM. It improves performance by minimizing the number of DOM manipulations during updates.

9. Question: What is a React.js hook?

Answer: A hook in React.js is a function that allows functional components to "hook into" React state and lifecycle features. Examples include useState and useEffect.

10. Question: How do you render a list of items in React.js?

**Answer:** You can render a list of items in React.js by mapping over an array and returning JSX for each item, like this: 
```jsx { => <li key={}>{}</li>)} ```

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