React Js Online Test

1. Which command is commonly used to start a React Native project?

react-create-app npm init npx react-native init yarn create react-native-app

2. In React, how do you handle asynchronous API requests to ensure that data is retrieved successfully?

By using callbacks By using synchronous functions By using the await keyword By using the return statement

3. What happens if you omit the else block in a conditional rendering statement in React?

It results in a syntax error The component will not render any content The component will always render The component will throw an error

4. Which React Router component is used to handle 404 (Not Found) routes?

<Route> <NotFound> <Switch> <Error>

5. In React Native, what is the main programming language used for writing mobile apps?

JavaScript Java Swift C++

6. Which command is used to create a new React application using Create React App (CRA)?

create-react-app npm install react react init app npm create-react

7. In React, what should you do if an error boundary catches an error that it cannot handle?

Log the error and display a friendly message Rethrow the error to the parent error boundary Ignore the error and continue rendering Restart the entire application

8. When does an error boundary catch errors in React?

During component rendering In the development environment only In the production environment only In both development and production environments

9. What is the primary benefit of using Hooks in React?

Simplicity and reusability Enhanced performance Improved security Server-side rendering

10. What is the term used to describe React's ability to update only changed parts of the user interface?

Efficient Rendering Dynamic Reconciliation Virtual DOM Component Reusability

11. What is the purpose of the <Link> component in React Router?

To create a hyperlink To define a new route To render a component To manage state in a route

12. In React, what is the purpose of the getDerivedStateFromError lifecycle method in error boundaries?

To log errors to the console To handle errors and update component state To trigger a re-render of the component To prevent errors from occurring

13. In React, how are events typically named?

In camelCase In kebab-case In snake_case In PascalCase

14. Which testing library provides utilities for querying and interacting with React components in tests?

Jest React Testing Library Enzyme Mocha

15. Which of the following is true about React components?

They cannot be reused They are always stateful They can be nested within other components They don't accept props

16. What does the src directory typically contain in a React project?

Source code for the application Built and optimized files Test files Documentation

17. In a functional component, how do you update the state variable declared with the useState Hook?

By calling the state variable directly By using the setState function By calling the useState function By invoking the useEffect Hook

18. What is one of the benefits of using error boundaries in React?

Improved debugging and error isolation Faster component rendering Increased application speed Reduced code complexity

19. Which of the following is not a commonly used hosting service for deploying React applications?

GitHub Pages Netlify Heroku ReactHub

20. What does the term "API" stand for in the context of web development?

Application Programming Interface Asynchronous Programming Interface Advanced Programming Interface Automatic Programming Interface