250+ React Js MCQ With Online Practice Test

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.

Practice Test

31. What are Props in React?

Answer: Component inputs

32. How does data flow between components in React using Props?

Answer: Unidirectional

33. In a class component, how can you initialize the component's state?

Answer: Using this.state in the constructor

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

Answer: Initializing component state

35. In React, can you modify the value of props directly within a component?

Answer: No

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

Answer: Using props

37. Which type of data is typically stored in component state in React?

Answer: User input

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

Answer: By invoking setState method

39. What happens when the state of a React component changes?

Answer: The component re-renders

40. What is one key advantage of using props and state in React components?

Answer: Component reusability
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React Js Multiple Choice Questions React Js MCQ React Js Interview Questions With Answers