JavaScript Major Questions
🔸 Implement the compose() and pipe() polyfill
🔸 Promises (Polyfill for Promise.all, Promise.race, Promise.allSettled)
🔸 Implement the map, filter, reduce, and forEach polyfills
🔸 Implement the Function.bind, call, and apply methods on the Function prototype
🔸 Implement Async.parallel and Async.series for executing async tasks
🔸 Build a Promise from scratch
🔸 Implement a Retry API
🔸 Implement Memoization
🔸 Currying (with examples)
🔸 String.prototype.repeat
🔸 Design patterns (Singleton, Factory patterns, Builder etc.)
🔸 Implement the Publisher-Subscriber pattern in JavaScript
🔸 Prototype and prototype inheritance
🔸 How rendering works in the browser
🔸 Event delegation and event propagation in JavaScript
🔸 Progressive Web Applications (PWAs)
🔸 Clone an object
🔸 Debouncing and Throttling
🔸 Implement clearAllTimeout()
🔸 How does "this" work in different scenarios?
🔸 What is the difference between synchronous and asynchronous code?
🔸 Explain the concept of "truthy" and "falsy" values.
🔸 What are template literals in ES6?
🔸 How do you handle errors in JavaScript?
🔸 Implement a function to flatten a nested array
🔸 Implement an LRU Cache
🔸 What are closures in JavaScript?
🔸 Explain the event loop in JavaScript.
🔸 What is the difference between 'var', 'let', and 'const'?
🔸 How does hoisting work in JavaScript?
🔸 What is the purpose of 'setTimeout' and 'setInterval'?
🔸 Explain how to use the Fetch API.
🔸 What is a service worker in the context of PWAs?
🔸 Describe how to implement deep cloning of an object.
🔸 What are modules in JavaScript? How do you use them?
🔸 Explain the concept of `this` binding with examples.
🔸 What is a closure? Provide an example.
🔸 How do you prevent default behavior of an event?
🔸 What are arrow functions, and how do they differ from regular functions?
🔸 Explain the concept of promises chaining.
🔸 What is the purpose of 'Object.create()'?
🔸 How can you check if an object is an array?
🔸 What are IIFE (Immediately Invoked Function Expressions)?
🔸 Explain how to create a custom event in JavaScript.
🔸 What is JSON, and how do you parse it?
🔸 Describe how to implement a simple event emitter.
🔸 What are weak references in JavaScript?
🔸 How do you optimize performance in large-scale applications?
🔸 Explain how to use localStorage and sessionStorage.
🔸 What are some common security issues in JavaScript applications?
1. What are the limitations of React in building large-scale applications?
2. How does React manage the Virtual DOM, and what are the benefits?
3. Can React Hooks fully replace Redux for state management? Explain why or why
not.
4. What are the best practices for managing state in large React applications?
5. How would you optimize performance in a React app with large component trees?
6. Explain React's Strict Mode and its impact on development.
7. How can you prevent unnecessary re-renders in React functional components?
8. Describe the key differences between functional and class components in React.
9. What is the significance of the React Fiber architecture?
10. How does React handle side effects, and how can you manage them effectively?
11. Explain the differences between `useMemo()` and `useCallback()` in React.
12. How would you implement dynamic form handling and validation in React?
13. What is lazy loading in React, and how does it improve application performance?
14. How would you handle errors in a React app, and what is the role of error
boundaries?
15. What are the benefits of server-side rendering (SSR) in React applications?
16. How do you handle styling in React components? Discuss different approaches.
17. How would you pass data between sibling components in React without using
Redux?
18. Explain the use case of `useEffect()` for fetching data from an API.
19. How do you handle asynchronous operations in React using `async/await` or
Promises?
20. How would you re-render a component when the window is resized?
21. Describe how React Context API can be used for state management in an app.
22. What is the role of React Router, and how does it work with dynamic routing?
23. Explain the concept of controlled and uncontrolled components in React.
24. How would you optimize React app performance when handling large lists or
grids?
25. Explain the difference between shallow and deep comparison in React's
`shouldComponentUpdate`.
26. How do you handle asynchronous code execution and state updates in React?
27. How would you implement custom hooks to abstract logic in React?
28. What are higher-order components (HOCs) in React, and how are they used?
29. How would you implement a search feature with debouncing in React?
30. Explain React's reconciliation process and how it updates the DOM efficiently.
1. How does React handle memory management, and what are some common memory leaks
to watch for?
2. What are React Portals, and when would you use them?
3. How do you handle authentication and authorization in a React app?
4. What are Suspense and Concurrent Mode, and how do they improve performance?
5. How do you prevent stale closures when working with useEffect?
6. How would you implement an infinite scrolling list in React?
7. What’s the best way to persist state across page reloads in a React app?
8. How does React batch state updates, and when does it not batch them?
9. How do you measure and optimize render performance in React applications?
