React Js Online Test

1. 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

2. What is the name of the React Native component that serves as the fundamental building block of UI in an app?

<View> <Layout> <Block> <Container>

3. What is a potential drawback of Server-Side Rendering (SSR) in React?

Complexity of server setup Inability to use JSX Slower rendering on the server Lack of support for CSS-in-JS libraries

4. In React, what is a component?

A server-side script A functional unit of user interface A database schema A CSS stylesheet

5. What is the purpose of the useReducer Hook in React state management?

To fetch data from APIs To manage component rendering To manage complex state logic To define a new route

6. In JSX, how do you render a JavaScript expression within curly braces?

{{ expression }} { expression } () expression

7. What is the recommended naming convention for React component files?

CamelCase kebab-case snake_case PascalCase

8. 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

9. In Redux, what is the central component responsible for managing the application state?

Reducer Middleware Store Action

10. In React DevTools, what is the purpose of the "Components" tab?

To view a list of installed npm packages To browse and inspect React component tree To edit the app's source code To check the network requests

11. In React, what is the purpose of the else block when using conditional rendering?

To define styles for components To conditionally render content To set state in components To create a new component

12. Which of the following is NOT a valid Route component prop in React Router?

path component render click

13. In React, what is a higher-order component (HOC)?

A component that is placed higher in the component tree A component that returns another component A component that has a higher specificity A component with higher rendering performance

14. What is the primary difference between class components and functional components in React?

Class components use lifecycle methods Functional components use hooks Class components have better performance Functional components cannot accept props

15. What is the primary role of the constructor method in a class component?

Initializing component state Defining component structure Rendering the component's UI Handling component events

16. In React, what is the recommended approach for handling errors when making API requests?

By using try-catch blocks By using inline comments By ignoring errors By using external error handling libraries

17. Which JavaScript library is often used in conjunction with React for state management?

Redux jQuery Lodash Express

18. 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

19. 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

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

useEffect useState useLifecycle useComponent