Mastering React.js by answering top interview questions

Discover how to apply the composition pattern in React to reuse one styled component across pages by passing content via props.children and toggling borders with props, avoiding duplicate components.

Learn to implement real-time news updates in a React app with WebSockets, using componentDidMount or useEffect, and manage messages with state and proper cleanup.

Demonstrates fixing a bubbling onClick in nested divs by using event.stopPropagation to prevent the parent click handler from firing, ensuring a single alert when the child is clicked.

Learn how to prevent needless re-renders in React by memoizing a heavy calculation with useCallback and wrapping child components with React.memo, ensuring stable function references and efficient rendering.

Learn to optimize a React app by using useMemo to memoize an expensive 1 million iteration calculation, so color changes don’t trigger the calculation while contour updates trigger a recomputation.

Create a custom hook to toggle user data visibility in a React app, exporting visible and toggle, and use it in App.js to show name, email, and username on click.

Use react's useId to generate unique input ids and link labels with htmlFor, ensuring correct focus; extend by appending identifiers for additional inputs.

Learn to build a high order component (hoc) that fetches API data, parses JSON, and upgrades a users component by passing the data as props to display names and emails.

Explore the render props pattern in React by building a reusable input component for Fahrenheit–Celsius conversions and a multiply-by-two display, rendered in pink headers.

Learn server side rendering (SSR) with React to deliver the fully rendered HTML for SEO, contrasting CSR and hydration, and explore practical setup with Node, Express, and Babel.

Build and manage a Redux store to load products, persist a signed-in user across pages, and enable logout, using slices, thunks, and React hooks for a seamless UI.

Mastering React.js demonstrates a front-end pagination approach for a post's comments, slicing all comments into five-per-page with next and previous links, fetching from a backend on port 5000.

Learn to keep the user interface responsive by using React's useTransition to prioritize input updates over heavy name generation, enabling typing while names render in the background.

Delay updates when typing to prevent rendering 20,000 usernames, using useDeferredValue instead of useTransition. Learn how delaying the input value reduces re-renders and improves performance in a React app.