Most React js Interview Questions and Answers – Part 2

Are you preparing for a React js interview? Here are some more commonly asked interview questions and their answers to help you prepare:

Question 1: What is the use of keys in React?

Answer: Keys are used in React to give a unique identity to each child component in an array. This helps React identify which items have changed, been added or removed. Keys should be given to the elements inside the array to give the elements a stable identity.

Question 2: What is the use of PropTypes in React?

Answer: PropTypes is used in React to type check the props that are passed to a component. It helps in validating the type of props being passed and ensures that the correct type of data is being passed to the component.

Question 3: What are Pure Components in React?

Answer: Pure Components are similar to functional components in that they do not have their own state and do not use lifecycle methods. However, they have a built-in shouldComponentUpdate method that helps in performing a shallow comparison of the props and state to determine if the component should re-render or not.

Question 4: What are Higher Order Components (HOC) in React?

Answer: Higher Order Components are a pattern in React where a function takes a component and returns a new component with additional functionality. This allows for reusability of code and separation of concerns in React components.

Question 5: What is JSX in React?

Answer: JSX (JavaScript XML) is a syntax extension for JavaScript that allows for writing HTML-like code within JavaScript. It allows for the creation of React elements in a more readable and familiar syntax, making it easier to write UI components in React.

These are just a few of the many questions you may encounter in a React js interview. It’s important to not only know the answers to these questions, but to also have a good understanding of the underlying concepts and principles of React. Good luck with your interview preparation!