React JS Interview Questions (Multi Select Search)
Frontend machine coding interview experience
Question 1: What is React JS?
React is a JavaScript library for building user interfaces. It allows developers to create interactive user interfaces efficiently by using a component-based approach.
Question 2: What are the key features of React?
- Virtual DOM
- JSX
- Components
- Uni-directional data flow
Question 3: What is the difference between state and props in React?
State is managed within a component and can be updated using the setState method, while props are read-only and passed down from a parent component to a child component.
Question 4: Explain the concept of JSX in React.
JSX is a syntax extension for JavaScript that allows developers to write HTML-like code within their JavaScript files. It makes React code more readable and helps in creating reusable components.
Question 5: What are the different lifecycle methods in React?
- componentDidMount
- componentDidUpdate
- componentWillUnmount
Question 6: How do you handle events in React?
Events in React are handled by using event handlers like onClick, onChange, etc. These handlers are specified as attributes in JSX and are passed a function to be executed when the event occurs.
Question 7: Explain the concept of Higher Order Components (HOC) in React.
HOCs are functions that take a component and return a new component with additional functionality. They are used to share common logic between multiple components and enhance reusability.
Question 8: What are the advantages of using React for web development?
- Virtual DOM for improved performance
- Reusable components for easier maintenance
- JSX for better code readability
- Uni-directional data flow for predictable state management
Question 9: How do you optimize performance in a React application?
Performance in a React application can be optimized by minimizing the number of re-renders, using pure components, and implementing shouldComponentUpdate method to prevent unnecessary updates.
Question 10: Explain the concept of context in React.
Context in React is used to pass data through the component tree without having to pass props down manually at every level. It provides a way to share data between components without explicitly passing it through props.
