React Js Online Test

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

CamelCase kebab-case snake_case PascalCase

2. What is the purpose of the ternary conditional operator (? :) in conditional rendering?

To define styles for components To simplify component structure To conditionally render content To manage state in components

3. What is the primary purpose of making HTTP requests in a React application?

To improve the application's performance To retrieve data from external APIs To style components To define component structure

4. What is AWS Lambda, and how is it commonly used with React?

A serverless compute service on AWS A frontend JavaScript library A database management system A testing framework

5. How can you access device features like the camera or GPS in a React Native app?

By writing custom native modules By using JavaScript libraries By embedding HTML code By configuring the app's settings

6. What is the primary difference between componentWillReceiveProps and static getDerivedStateFromProps?

They are the same method componentWillReceiveProps is deprecated static getDerivedStateFromProps is static static getDerivedStateFromProps is called before rendering

7. In React, how can you update the component's state?

By directly modifying this.state By invoking setState method By reassigning the state object By using props

8. In React, what is the recommended approach for rendering a list of elements conditionally?

By using the if-else statement By using the map method By using the switch statement By using the for loop

9. 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

10. In React, how do you add CSS classes to components using JSX?

By using the class attribute By using the styles attribute By using the className attribute By using the style attribute

11. How do you render one component if a condition is true and another component if it's false in React?

By using the if-else statement By using the render method By using the setState method By using JSX conditional expressions

12. What is the recommended way to pass data from a parent component to a child component in React?

Using props Using state Using context Using Redux

13. 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

14. In React, what does the defaultValue prop do when used with an input element?

It sets the initial input value It triggers an event when the input changes It prevents user input It displays placeholder text

15. In React, how can you include one component within another component's JSX?

By using the import statement By using the include directive By using the import function By using the compose method

16. What is a common method for optimizing images in a React application before deployment?

Using a version control system Compressing and resizing images Minifying JavaScript code Installing more RAM

17. In React, how do you conditionally apply styles to components based on component state or props?

By using conditional statements By using the style attribute By using external CSS files By using the class attribute

18. What is the recommended way to control the rendering of child components in React?

By using conditional rendering By using the this.renderChild method By using the render prop By using the renderChild prop

19. 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

20. Which CSS preprocessor is often used in combination with React for enhanced styling capabilities?

Sass HTML JavaScript TypeScript