React Js Online Test

1. In React, how do you handle user input in controlled components?

By using the onChange event By using the onClick event By using the onSubmit event By using the onMouseOver event

2. What is the key advantage of Server-Side Rendering (SSR) for improving perceived performance?

Faster server response times Reduced server load Faster client-side rendering Reduced network latency

3. In React, what is the purpose of the key prop when rendering a list of components?

To specify the list item's content To define a unique identifier To style the list items To control the list's state

4. What is the purpose of the <Redirect> component in React Router?

To redirect to a different URL To define a new route To render a component conditionally To create a hyperlink

5. What does the "Props" panel in React DevTools display?

The list of installed npm packages The state of the Redux store The properties and values of a component The app's source code

6. How can you conditionally render content in a React component using JSX?

By using the if statement By using the render method By using the conditional attribute By using the if-else expression

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

JavaScript Java Swift C++

8. 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

9. 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

10. What are React components primarily used for?

Managing server-side data Defining the structure of web pages Writing server-side scripts Running unit tests

11. In a functional component, how do you manage state using React Hooks?

By using the constructor method By directly modifying the state variable By using the useState Hook By creating a separate state function

12. What is a common use case for serverless integration in a React application?

Building APIs and handling user authentication Managing application state Developing interactive UI components Configuring Babel settings

13. 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

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

npm Yarn Bower Grunt

15. 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

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

Simplicity and reusability Enhanced performance Improved security Server-side rendering

17. In React, what is conditional rendering?

Rendering components conditionally Always rendering all components Defining styles for components Storing component data

18. Which of the following HTTP methods is typically used for fetching data from an API in React?

GET POST DELETE PUT

19. What is the purpose of the shouldComponentUpdate lifecycle method?

To check if a component should re-render To update the component's state To fetch data from an API To render the component's UI

20. Which lifecycle method is commonly used to fetch data from an API in a React component?

componentDidMount componentWillUnmount componentWillMount render