Evergreen React interview questions
React.js continues to be a leading choice among developers and businesses for building interactive and efficient user interfaces. As you prepare for your next React interview, it's essential to familiarize yourself with evergreen questions that consistently appear. Here are some of the most popular and crucial React interview questions:
1. What is React?
React is a JavaScript library developed by Facebook for building user interfaces, especially single-page applications (SPAs). It allows developers to create reusable UI components.
2. Explain JSX.
JSX (JavaScript XML) is a syntax extension for JavaScript used in React to describe the UI. JSX resembles HTML and makes it easier to write and visualize React components.
3. What are components in React?
Components are independent, reusable bits of code that manage their own state and rendering logic. They come in two types: functional and class components.
4. What is state in React?
State is an object managed within components, holding information that influences the rendering and behavior of the UI. State can change over time and trigger re-renders.
5. Explain props in React.
Props (short for properties) are inputs passed to components. They allow data and functions to flow from parent components to child components.
6. What is the Virtual DOM?
The Virtual DOM is a lightweight JavaScript representation of the real DOM. React uses it to improve performance by batching and efficiently updating UI changes.
7. Explain the lifecycle methods in React.
Lifecycle methods are special methods in class components that execute at specific points during a component's lifecycle, such as mounting, updating, and unmounting. Examples include componentDidMount, componentDidUpdate, and componentWillUnmount.
8. What are hooks?
Hooks are functions introduced in React 16.8 that allow functional components to manage state and lifecycle events. Common hooks include useState, useEffect, and useContext.
9. How do you manage state globally?
State management libraries like Redux or built-in solutions like React's Context API help manage state globally, making it accessible across multiple components.
10. Explain the difference between controlled and uncontrolled components.
Controlled components' form data is handled by React state, making React the source of truth. Uncontrolled components rely on the DOM to handle form data, typically using refs.
11. What is React Router?
React Router is a popular library used for routing in React applications. It enables navigation and dynamic rendering of components based on URL paths.
12. How can you optimize React performance?
Performance optimization strategies include using React.memo, avoiding unnecessary re-renders with proper state management, lazy-loading components, and code splitting.
Knowing these questions well will enhance your confidence and performance in any React interview, setting you apart from the competition. Good luck!