JavaScript Interview Questions With Answers

If you have been trying to prepare for front-end engineering interviews, and are struggling to find what are the most commonly asked questions, you are not alone. This page collects the most common JavaScript interview questions, with links to MDN’s JavaScript reference for deeper reading.

We understand the struggle, which is why we have aggregated the most frequently asked Front-end JavaScript interview questions, sourcing them from various platforms, including Glassdoor, Blind, and others, to identify the most commonly asked questions in front-end interviews conducted by companies such as Meta, Google, Apple, Robinhood, and more.

In this article, we will showcase the 75 most commonly asked Frontend interview questions in JavaScript.

We want to highlight something significant — a significant mistake you can avoid. Understanding the question accounts for 50% of the struggle, while knowing the correct solution makes up the other 50%. Before diving deep into studying these questions, you might think, “I already know the solutions.” However, there are many ways to solve the same question, and top companies are looking for the most optimized approach, particularly in front-end development.

Below is the list of the top 75 questions to expect during frontend interviews. Each question has a solution, which can be accessed by clicking on the solution tab.

Top 75 Frontend JavaScript Questions

• 1. Find Corresponding Node
• 2. Improve a function
• 3. Flatten I
• 4. Debounce I
• 5. Throttle
• 6. Total Salaries
• 7. Gym Sessions
• 8. Array Methods
• 9. Build Promise
• 10. ClassNames
• 11. Create DOM
• 12. Phone Number Parser
• 13.Deep Clone
• 14. Event Emitter
• 15. EventTarget
• 16. Traverse DOM
• 17. Flatten II
• 18. Intersection Observer
• 19. Memoize I
• 20. Masonry Grid
• 21. Navigation
• 22. Next Right Sibling
• 23. Node Store
• 24. Parser for Rich Text Editor
• 25. Promisify Any Function
• 26. Skill Endorsements
• 27. Testing Framework
• 28. Text Highlighter
• 29. Throttle II
• 30. Tic Tac Toe
• 31. Top K Words
• 32. Image Slider
• 33. Virtual DOM I
• 34. Virtual DOM II
• 35. Virtual DOM III
• 36. API Confirmation
• 37. API Search and Render Image
• 38. Asynchronous Request Queue
• 39. Auto Suggest Search List
• 40. Autocomplete Search List
• 41. ClearAllIntervals()
• 42. ClearAllTimeouts()
• 43. Compose Function
• 44. Curry Function
• 45. Custom “this” Methods
• 46. Debounce II
• 47. Debounce III
• 48. Deep Equals
• 49. Event Emitter II
• 50. Event Logger I
• 51. Event Logger II
• 52. File Navigation
• 53. Filtering Matching JSON
• 54. Flatten III
• 55. Flatten IV
• 56. Flatten V
• 57. Flatten VI
• 58. Flatten VII
• 59. Flatten XI
• 60. getElementsByClassName
• 61. Hierarchical Checkbox
• 62. Histogram
• 63. Infinite Scrolling News Feed
• 64. K MostText Nodes
• 65. Memoize II
• 66. Promise Methods
• 67. querySelectorAll
• 68. Rate Limiter
• 69. Animate Element To The Right
• 70. RxJS Observable
• 71. Set Interval with Linear Delay
• 72. Stream
• 73. String Repeater
• 74. Tabs
• 75. Todo App

In conclusion, navigating the landscape of front-end engineering interviews can be a daunting task, especially when it comes to knowing what to expect and how to prepare. Our focus was to move beyond the algorithm-heavy questions typical of many coding interviews and instead, zero in on questions that test a candidate’s practical, domain-specific knowledge.

Remember, understanding the question is just as crucial as knowing the answer. It’s not enough to have a superficial grasp of the solutions; what sets candidates apart is their ability to apply the most efficient and optimized solutions to problems, particularly in the fast-evolving field of front-end development. To aid in this, we introduced frontendlead.com, a resource designed to offer in-depth explanations and video tutorials for each question, ensuring you’re well-equipped to tackle any challenge that comes your way in a front-end engineering interview.