1. What are the differences between null and undefined in JavaScript?
2. Explain the concept of hoisting in JavaScript.
3. How do you implement a custom iterator in JavaScript?
4. What are the differences between function declarations and function expressions?
5. How do closures work in JavaScript, and what are their use cases?
6. Explain the prototype chain and how it relates to inheritance in JavaScript.
7. What is the purpose of the this keyword in JavaScript?
8. How does this behave differently in arrow functions compared to regular functions?
9. What are the implications of using eval() in JavaScript?
10. Explain the concept of asynchronous programming in JavaScript.
11. What are the differences between Promise and async/await?
12. How do you handle promise rejection in asynchronous functions?
13. What is the purpose of the finally method in Promises?
14. Explain the event loop and how it handles asynchronous operations.
15. How do microtasks and macrotasks differ in JavaScript?
16. What is a JavaScript closure, and how can it be used to create private data?
17. Explain the module pattern and its advantages in JavaScript.
18. What is the difference between Object.defineProperty() and property assignment?
19. How do you create a singleton in JavaScript?
20. What is the purpose of the Object.freeze() method?
21. How do you implement method chaining in JavaScript?
22. What are JavaScript decorators, and how can they be used?
23. Explain how to use the Proxy object for meta-programming.
24. What are the advantages of using WeakMap and WeakSet?
25. How do you create a custom error class in JavaScript?
26. What is the purpose of the try...catch statement in error handling?
27. How do you create a memoization function to optimize performance?
28. Explain the significance of the Symbol data type in JavaScript.
29. What is the Reflect API, and how does it enhance object manipulation?
30. How do you use Map and Set in JavaScript, and what are their advantages?
31. What are the performance implications of using Array.prototype.push() vs. unshift()?
32. How does the Array.prototype.sort() method work under the hood?
33. Explain how to use the requestAnimationFrame() method for smooth animations.
34. What is the IntersectionObserver API, and how can it improve performance?
35. How do you implement a custom event system in JavaScript?
36. What are service workers, and how do they enable offline capabilities?
37. Explain how to use the Cache API with service workers.
38. What are the differences between client-side and server-side rendering?
39. How do you optimize performance in large JavaScript applications?
40. Explain the purpose of the fetch() API and how to handle errors.