Question 1: What are React Hooks, and How Do They Differ from Class Components?
Answer: React Hooks are functions introduced in React 16.8 that allow you to use state and other React features in functional components. They enable you to manage component state and lifecycle features without writing class components. The key difference is that Hooks allow you to reuse stateful logic across components without changing their structure into class components.
Question 2: How Does React Virtual DOM Work, and Why Is It Important?
Answer: React Virtual DOM is an in-memory representation of the actual DOM. When changes occur in a React component, React first updates the Virtual DOM, then compares it with the previous Virtual DOM snapshot, and finally, it calculates the minimum number of DOM operations needed to update the actual DOM. This process makes updates more efficient, resulting in better performance and a smoother user experience.
Question 3: What Are Higher-Order Components (HOCs), and When Should You Use Them?
Answer: Higher-Order Components (HOCs) are functions that take a component and return a new component with additional props or behavior. They are used for code reuse, prop manipulation, and cross-cutting concerns like authentication and logging. HOCs are useful when you want to share logic among multiple components without duplicating code.
Question 4: What Is React Fiber, and Why Was It Introduced?
Answer: React Fiber is a reimplementation of React core algorithm for rendering and updating the UI. It was introduced to improve the responsiveness of React applications by breaking down the rendering work into smaller chunks and allowing interruption and prioritization of tasks. This makes React more efficient and capable of handling complex, high-priority updates.
Question 5: What Is Context in React, and When Should You Use It?
Answer: React Context is a mechanism for sharing data between components without explicitly passing props through the component tree. It’s used when you have data that needs to be accessible to many components at different nesting levels. Context is particularly helpful for managing global state, such as themes, authentication, or localization.
Question 6: What Is the Purpose of React Fragments?
Answer: React Fragments, represented as <></> or <React.Fragment>, are used to group multiple elements without adding extra nodes to the DOM. They help in avoiding unnecessary divs or spans when rendering components. Fragments improve the structure and performance of your components.
Question 7: What Is Server-Side Rendering (SSR) in React, and Why Is It Beneficial?
Answer: Server-Side Rendering (SSR) in React involves rendering the initial HTML on the server and sending it to the client. SSR offers benefits like faster initial page loads, improved SEO, and better perceived performance. It’s beneficial for applications that require SEO optimization or faster time-to-interactive.
Question 8: What Are React Portals, and How Can They Be Useful?
Answer: React Portals provide a way to render a component’s children at a different place in the DOM tree. They are useful for scenarios like modals, tooltips, or popovers where you need to render content outside the parent component’s DOM hierarchy while keeping the component’s state intact.
Question 9: Explain the Concept of Code Splitting in React.
Answer: Code splitting is the practice of breaking your application’s bundle into smaller, more manageable chunks that are loaded on-demand. It reduces the initial load time and improves performance. In React, you can use tools like React.lazy() and the Suspense component to achieve code splitting.
Question 10: How Do You Optimize the Performance of a React Application?
Answer: To optimize React application performance, you can:
- Use shouldComponentUpdate, PureComponent, or memoization to prevent unnecessary renders.
- Profile your app with tools like React DevTools and Chrome DevTools to identify performance bottlenecks.
- Implement lazy loading and code splitting to reduce initial bundle size.
- Use server-side rendering (SSR) for faster initial rendering.
- Employ caching mechanisms for data fetching.
- Minimize the use of expensive operations in render methods.
