React Js Online Test

1. In a React form, how do you prevent the default form submission behavior when handling form submission?

By using the e.preventDefault() method By using the form.preventDefault() method By using the form.preventSubmit() method By using the e.preventFormSubmit() method

2. Which of the following is NOT a common state management library for React?

Redux MobX GraphQL Zustand

3. In React, what is the purpose of the componentDidCatch lifecycle method?

To log errors to the console To handle errors and display a fallback UI To trigger a re-render of the component To prevent errors from occurring

4. What does an HTTP status code of "404" typically indicate when making an API request in React?

Resource not found Unauthorized access Server error Successful request

5. Which platform(s) can you build mobile apps for using React Native?

iOS and Android Windows and macOS Linux and Ubuntu All of the above

6. What is the primary advantage of deploying a React application using a Content Delivery Network (CDN)?

Faster loading times Enhanced security Access to server logs Better error handling

7. What is the advantage of using a serverless authentication service like AWS Cognito in a React application?

It provides secure user authentication It optimizes CSS styles It manages serverless functions It compiles TypeScript code

8. In a functional component, how do you declare and use a state variable using the useState Hook?

const [state, setState] = useState(initialValue) const state = useState(initialValue) const [state] = useState(initialValue)

9. What is the purpose of the hydrate() method when using SSR in React?

To disable client-side rendering To start the client-side rendering To fetch data from the server To pause rendering on the server

10. Which Redux function is used to dispatch actions to update the state in a Redux store?

getState dispatch subscribe mapStateToProps

11. Which built-in Hook is used for performing side effects in a functional component?

useEffect useState useRender useLifecycle

12. In which lifecycle method can you use code splitting and lazy loading in a React component?

componentDidMount componentWillUnmount constructor render

13. Which React Router component is used to define the routes in a React application?

<Route> <Router> <Link> <App>

14. In functional components, which React hook replaces lifecycle methods like componentDidMount?

useEffect useState useLifecycle useComponent

15. Which package manager is commonly used for managing React projects and dependencies?

npm Yarn Bower Grunt

16. Which of the following data formats is commonly used for API responses that contain structured data in React?

JSON XML HTML CSV

17. What is the purpose of the package.json file in a React project?

To specify project dependencies To store component code To define global styles To configure Webpack settings

18. What is the role of Babel in the React ecosystem?

To compile JSX to JavaScript To create React components To manage application state To handle server requests

19. What is the purpose of the fetch() function in React when making API requests?

To create a new component To retrieve data from an API To apply styles to components To set component state

20. What is the purpose of a build tool like Webpack or Parcel in React application deployment?

To run the application locally To optimize and bundle the code To create a new React component To manage state in Redux