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

1. Explain the concept of server-side rendering (SSR) in React and its advantages.

SSR is a technique to render React components on the server and send HTML to the client

SSR is used for handling client-side routing in React

SSR is a replacement for the useEffect hook

SSR eliminates the need for component state

2. Explain the purpose of the useReducer hook in React.

To handle routing in React applications

To manage complex state logic in functional components

To define the initial state of a component

To handle asynchronous operations

3. What is the role of the arrow function in React?

To create components

To bind event handlers

To define state

To initialize props

4. What is the purpose of the key attribute in React lists?

It uniquely identifies elements in an array

It sets the background color of elements

It defines the order of elements

It is used for styling purposes

5. 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

6. 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

7. 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

8. What is the significance of React portals?

To create reusable components

To render content outside the DOM hierarchy of a parent component

To handle routing in React

To manage global state in React applications

9. What is the role of the useHistory hook in React Router, and how can it be used?

To manipulate the browser's history

To define the initial state of a component

To manage context API in functional components

To handle asynchronous operations in functional components

10. 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

11. How can you handle global state management in a React application without using Redux?

By using the useContext hook

By relying solely on component state

By creating a global variable outside the React component tree

By using the useReducer hook

12. 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

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. Explain the concept of 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

15. What are Higher Order Components (HOCs) in React, and how do they work?

Components with a higher level of complexity

Components that use hooks extensively

Functions that return components with enhanced functionality

Components that follow a specific naming convention

16. What are Hooks in React, and why were they introduced?

Hooks are functions that let you use state and lifecycle features in functional components

Hooks are event listeners in React

Hooks are a replacement for class components

Hooks are used for styling in React

17. How can you handle conditional rendering in React?

Using the switch statement

Using the if statement

Using ternary operators

Using the map function

18. How can you handle events in React?

By using the onClick event

By using the bind method

By using the addEventListener method

By using the onEvent prop

19. What is the purpose of the useDebugValue hook in React, and how can it be beneficial?

To optimize rendering performance in React

To define strict coding rules for React components

To debug React components during development

To provide custom names for hooks in React DevTools

20. How does React handle prop drilling?

By passing props through multiple components

By avoiding the use of props

By directly modifying parent components

By using Redux for state management

21. 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

22. What is the significance of the 'key' prop in React lists?

It defines the component's identity

It specifies the component's style

It sets the component's position

It helps React identify which items have changed, are added, or are removed

23. 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

24. What is the significance of the React memo function, and how can it optimize performance?

React memo is used for styling in React components

React memo allows the creation of reusable components

React memo is a replacement for the shouldComponentUpdate method

React memo prevents unnecessary re-rendering of functional components

25. 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

26. How does React Router improve the navigation experience in a React application?

By providing a built-in state management system

By allowing the use of global variables for navigation

By synchronizing the UI with the URL

By preventing the use of dynamic routes

27. 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

28. 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

29. 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

30. How can you optimize performance in React?

By using class components

By using Redux

By using the PureComponent class

By using inline styles

31. What is the purpose of the key prop in React lists?

It sets the background color of elements

It defines the order of elements

It is used for styling purposes

It uniquely identifies elements in an array

32. 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

33. 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

34. What is the role of the React Router Switch component, and how does it impact route rendering in a React application?

The React Router Switch component is used for handling asynchronous operations

The React Router Switch component is used to define strict coding rules for React components

The React Router Switch component renders the first child that matches the current location

The React Router Switch component is a replacement for the useTransition hook

35. 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

36. What is the significance of the React.memo function, and how can it optimize performance?

React memo is used for styling in React components

React memo allows the creation of reusable components

React memo is a replacement for the shouldComponentUpdate method

React memo prevents unnecessary re-rendering of functional components

37. How can you conditionally render elements in React?

Using the if statement

Using the switch statement

Using the map function

Using ternary operators

38. 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

39. 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

40. What is the purpose of the useLayoutEffect hook in React, and how does it differ from useEffect?

To handle layout changes and synchronously apply effects

To manage component state during layout updates

To define the component's initial state

To handle asynchronous operations in functional components

React MCQ Test 2