Supreme React Test - 72+ MCQs: React test: Evaluate Your Proficiency with React Questions and Answers

1. Explain the concept of lazy loading in React and how it can improve performance.

Lazy loading is a method for delaying component rendering

Lazy loading is used to load external libraries in React

Lazy loading is a feature of React Suspense

Lazy loading has no impact on performance

2. What are React Hooks rules, and why is it essential to follow them?

Rules that dictate the naming convention of hooks

Guidelines for using hooks within class components

Guidelines for using hooks within functional components

Rules that define the lifecycle of a hook

3. Explain the concept of the React Virtual DOM and its impact on performance.

The Virtual DOM is a physical representation of the DOM

The Virtual DOM improves rendering speed by directly manipulating the actual DOM

The Virtual DOM is an alternative to using state in React

The Virtual DOM allows React to efficiently update only the changed parts of the UI

4. How does React handle prop drilling, and what are the alternatives to mitigate it?

React uses refs to avoid prop drilling

Prop drilling is inherent in React and cannot be mitigated

Context API can be used to avoid prop drilling

Redux is the only solution to prop drilling

5. Explain the concept of controlled components in React.

Components that are directly manipulated by the DOM

Components that maintain their own state

Components that rely on Redux for state management

Components that receive props from parent components

6. What is the role of the useMemo hook in React, and when should it be used?

To memoize functions and optimize performance

To manage component state in class components

To create references to DOM elements

To handle context API in functional components

7. Explain the role of the React Router Prompt component and when it should be utilized.

The React Router Prompt component is used for handling asynchronous operations

The React Router Prompt component is used to prompt the user before navigating away

The React Router Prompt component defines the initial state of a component

The React Router Prompt component is used for styling React components

8. What is the purpose of the withRouter HOC in React?

To handle routing

To create higher-order components

To manage component state

To define the component's lifecycle

9. In React, what is the significance of the useMemo hook?

To memoize functions

To manage component state

To handle side effects

To optimize performance

10. What does the term 'props drilling' refer to in React?

Passing data from child to parent components

Passing data through multiple layers of components

Passing data from parent to child components

Passing data using context API

11. Explain the purpose of the React Profiler tool and how it can be used for performance optimization.

The React Profiler tool is used to debug React components

The React Profiler tool is used for styling React components

The React Profiler tool helps analyze the rendering performance of components

The React Profiler tool is used for managing global state in React applications

12. What is JSX in React?

JavaScript XML

Java Syntax Extension

JavaScript Extension

Java XML Syntax

13. Explain the concept of custom hooks in React and provide an example of a scenario where they are useful.

Custom hooks are hooks provided by React for common use cases

Custom hooks are only applicable in class components

Custom hooks are functions that use React hooks and can be shared between components

Custom hooks are a replacement for using state in React

14. How does the useDeferredValue hook in React contribute to improving performance, and in what scenarios is it beneficial?

The useDeferredValue hook enhances the transition animations in React

The useDeferredValue hook is used for handling routing in React

The useDeferredValue hook improves the performance of asynchronous operations

The useDeferredValue hook delays the update of a value until after a specified timeout

15. Explain the concept of error boundaries in React and how they contribute to a better user experience.

Error boundaries catch errors during component rendering and log them to the console

Error boundaries prevent all errors from being logged

Error boundaries are not applicable in functional components

Error boundaries allow components to continue rendering despite errors

16. What is the purpose of state in React?

To store component properties

To manage component styling

To maintain component history

To manage component data over time

17. What is the purpose of the useCallback hook in React?

To memoize functions

To manage component state

To define the component's initial state

To handle side effects

18. What are the advantages of using the Redux library in a React application?

To simplify state management and make it predictable

To eliminate the need for component state

To handle form validation in React

To optimize rendering performance

19. What is the purpose of the Redux library in React applications?

To manage component state

To handle routing

To simplify state management

To style React components

20. How can you implement server-side rendering (SSR) with data fetching in a React application?

By using the useEffect hook for data fetching

By relying solely on client-side rendering for data fetching

By incorporating the useTransition hook for server-side rendering

By using a library like Next.js for server-side rendering

21. What is the purpose of the React.StrictMode component, and when should it be used?

To define strict coding rules for React components

To optimize rendering performance in React

To catch common coding mistakes and potential issues early

To handle routing in React applications

22. What are the benefits of using the React.forwardRef function, and in what scenarios is it useful?

React.forwardRef is used to create higher-order components

React.forwardRef is used for styling React components

React.forwardRef is beneficial for optimizing rendering performance

React.forwardRef allows the parent component to interact with a child's DOM node

23. How can you update the state based on the previous state in React?

By using the setState() method

By using the getSnapshotBeforeUpdate method

By using the useReducer hook

By passing a function to the setState() method

24. What is the purpose of the setState() method in React?

To update the component's state

To render JSX elements

To define the component's lifecycle

To handle user input

25. What is state in React?

A built-in object

A function

An object that stores component data

A global variable

26. What is the role of the dangerouslySetInnerHTML prop in React?

To set the component's initial state

To handle context API

To update the virtual DOM

To render HTML content dangerously

27. Explain the concept of code splitting in React and how it can improve application performance.

Code splitting is a method for writing concise React components

Code splitting is a feature of React Lazy

Code splitting is a technique to divide the application code into smaller chunks

Code splitting has no impact on application performance

28. What are the advantages of using the React Context API over prop drilling, and in what scenarios is it preferable?

The React Context API is more efficient for handling global state

The React Context API is only suitable for class components

The React Context API is less performant than prop drilling

The React Context API is beneficial for passing data through deeply nested components

29. What is the purpose of the shouldComponentUpdate method in React?

To check if a component should re-render

To define the component's initial state

To handle component lifecycle

To update the virtual DOM

30. How can you handle forms in React?

Using the form tag

Using the state object

Using the onSubmit event

Using the submit() method

React MCQ Test 3