250+ React Js MCQ With Online Practice Test

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React.js, often simply called React, is a highly popular JavaScript library for building user interfaces. Developed and maintained by Facebook, React is renowned for its component-based architecture and the ability to efficiently update and render components when data changes. It is a foundational tool for developing modern web and mobile applications, allowing developers to create dynamic and interactive user interfaces with ease. React's vast ecosystem, including tools like React Native for mobile app development, makes it a top choice for frontend development and a key player in the world of web technologies.

21. What does JSX stand for in React development?

Answer: JavaScript XML

22. What is JSX primarily used for in React?

Answer: Defining component structure

23. Is JSX mandatory to use when building React components?

Answer: Yes

24. How does JSX differ from regular HTML?

Answer: JSX uses camelCase for attributes

25. What is the main role of Babel in the context of JSX?

Answer: Converting JSX into JavaScript

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

Answer: { expression }

27. What is the purpose of using the className attribute in JSX instead of class?

Answer: To reference CSS classes

28. In JSX, how do you render a component that you've defined elsewhere?

Answer: <Component />

29. What happens when JSX is transpiled by tools like Babel?

Answer: JSX is converted to JavaScript

30. Which of the following is a valid JSX element in React?

Answer: <p>{text}</p>
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React Js Multiple Choice Questions React Js MCQ React Js Interview Questions With Answers