JavaScript Interview Questions

60 questions in this collection

0 free samples · 60 member questions

Frontend Developer Full Stack Developer Software Engineer Web Developer

Practice JavaScript interview questions on closures, asynchronous code and browser behavior. Explain your choices about object equality, rendering performance and reusable functions.

View Full Access Pricing

1. What is hoisting in JavaScript?

easy
2. What is the difference between == and === in JavaScript?

easy
3. How does this work in JavaScript?

easy
4. What is a closure in JavaScript?

easy
5. Explain Event Bubbling in JavaScript

easy
6. What is a Promise in JavaScript?

easy
7. When would you use map, filter, and reduce in JavaScript?

easy
8. What is the difference between Local Storage and Session Storage in the Web Storage API?

easy
9. Explain the difference between a function expression and a function declaration.

easy
10. What is the purpose of the array forEach method?

easy
11. Explain the concept of Prototypal Inheritance in JavaScript.

medium
12. How does JavaScript handle asynchronous code?

medium
13. Explain the concept and usage of IIFE in JavaScript.

medium
14. What is the difference between var, let, and const?

medium
15. What is the execution context in JavaScript and how is it created?

medium
16. How do you handle errors in JavaScript?

medium
17. What are JavaScript Generators and how do they work?

medium
18. Explain the concept of memoization in JavaScript.

medium
19. What is event delegation in JavaScript and how does it work?

medium
20. How can you achieve module encapsulation in JavaScript?

medium
21. What are Template Literals in JavaScript and how do they enhance code readability?

medium
22. Explain the differences between REST and GraphQL APIs from a JavaScript client perspective.

medium
23. How do JavaScript Promises differ from async/await?

medium
24. What is the purpose and usage of the Spread Operator in JavaScript?

medium
25. Discuss the significance of WebSockets in JavaScript and how they differ from HTTP requests.

medium
26. How can you ensure your JavaScript code is secure?

medium
27. What is a virtual DOM, and what are its performance tradeoffs?

medium
28. Explain the concept of currying in JavaScript and provide an example.

medium
29. What are Service Workers and how are they used in JavaScript applications?

medium
30. How do you optimize the performance of a JavaScript web application?

medium
31. Explain the concept of Event Loop in JavaScript.

hard
32. Implement a Deep Copy function for objects in JavaScript.

hard
33. Explain and implement a debounce function.

hard
34. Discuss the differences and use cases of Object.freeze(), Object.seal(), and const.

hard
35. How does the JavaScript engine handle memory leaks?

hard
36. Implement a function to perform a binary search on a sorted array.

hard
37. Explain the difference between shallow equality and deep equality in JavaScript.

hard
38. How can you prevent XSS attacks in a JavaScript application?

hard
39. Describe the process of tree shaking in JavaScript modules.

hard
40. What are Symbols in JavaScript and how can they be used?

hard
41. Implement a custom iterator in JavaScript that iterates over Fibonacci numbers.

hard
42. Discuss the impact of using async/await in loops.

hard
43. How do JavaScript proxies work and what are their applications?

hard
44. Explain the concept of code splitting in JavaScript and its benefits.

hard
45. Implement a function that flattens a nested array.

hard
46. Explain how JavaScript's call stack works.

hard
47. Discuss the concept of Higher-Order Functions in JavaScript.

hard
48. How can you handle large-scale state management in JavaScript applications?

hard
49. Explain the concept of reactive programming in JavaScript.

hard
50. What are Web Workers, and how can they be utilized in JavaScript applications?

hard
51. Discuss the significance and implementation of server-side rendering (SSR) in JavaScript applications.

hard
52. How can custom data attributes be used in JavaScript, and what are their benefits?

hard
53. Implement a pub/sub (publish/subscribe) system in JavaScript.

hard
54. Explain the role of the JavaScript task queue and microtask queue.

hard
55. What is the significance of the Shadow DOM in web components?

hard
56. How can you optimize the rendering of large lists in JavaScript?

hard
57. Explain the difference between classical inheritance and prototypal inheritance in JavaScript.

hard
58. How does JavaScript's garbage collection mechanism work?

hard
59. Discuss the use of WebAssembly in JavaScript applications.

hard
60. Implement a method to compare two JavaScript objects for equality.

hard

View Full Access Pricing

Related Collections

AI Ethics

43 Questions

Practice discussing bias, privacy and consent in AI systems. Work through ethical dilemmas and risk-assessment questions, and explain how you would weigh the c…

AI Explainability

43 Questions

Prepare to explain why an AI model made a prediction and what an explanation can reveal. Compare interpretation methods and discuss how transparency relates to…

AI Product Management

62 Questions

Practice making product decisions when AI capabilities, customer needs and uncertainty compete. Work through roadmap priorities, value measurement and ethical …