JavaScript Interview Guide

I am neither an expert book writer nor a great frontend engineer, I am someone who is curious and trying to fill a few gaps. There are many awesome books in the market that help you to get ready and crack the general Software Engineering or Backend interviews, but a very few with the focus on the Frontend. This is where the idea to create this book has hit. In 2019, I decided to run a blog (learnersbucket.com) with the sole aim of writing about frontend stuff that I couldn’t find on the web. I started with Data Structures & Algorithms in JavaScript and then ES6 concepts and later solved solutions for frontend interview questions gathered over the time from the web. Over 3 years I managed to get a decent exposure to my blog and had around 400 articles written. After getting some good writing experience I decided to consolidate things in the book format so that It will be easy to refer and use as a “JavaScript Interview Guide”. This book contains ● 100 JavaScript questions ● 20 React questions ● 2 System Design questions with solved solutions Along with these, I have tried to explain a few important concepts of JavaScript and there are many that you will learn along with each question. I don’t own the questions, along with the solution many things in the book you will find are referred from different sources. - Prashant Yadav (Senior Software Engineer) Table of Content Concepts 1. Closure 2. Array.reduce() method 3. Promises 4. Function & this JavaScript Questions 1. Promise.all() polyfill 2. Promise.any() polyfill 3. Promise.race() polyfill 4. Promise.finally() polyfill 5. Promise.allSettled() polyfill 6. Custom Promise 7. Execute async functions in Series 8. Execute async functions in Parallel 9. Retry promises N number of times 10. Implement mapSeries async function 11. Implement mapLimit async function 12. Implement async filter function 13. Implement async reject function 14. Execute promises with priority 15. Dependent async tasks 16. Create pausable auto incrementor 17. Implement queue using stack 18. Implement stack using queue 19. Implement stack with min and max method 20. Implement two stacks with an array 21. Implement Priority Queue 22. Implement LRU cache © JavaScript Interview Guide | learnersbucket.com 6 23. Implement debounce function 24. Implement debounce with immediate flag 25. Implement throttle function 26. Implement custom Instanceof 27. Check if function is called with new keyword 28. Implement hashSet 29. Create a toggle function 30. Create a sampling function 31. Make function sleep 32. Remove cycle from the object 33. Filter multidimensional array 34. Count element in multidimensional array 35. Convert HEX to RGB 36. Convert RGB to HEX 37. In-memory filesystem library 38. Basic implementations of streams API 39. Create a memoizer function 40. Method chaining - part 1 41. Method chaining - part 2 42. Implement clearAllTimeout 43. Implement clearAllInterval 44. Create a fake setTimeout 45. Currying - problem 1 46. Currying - problem 2 47. Currying - problem 3 48. Convert time to 24 hours format 49. Convert time to 12 hours format 50. Create a digital clock 51. Chop array in chunks of given size 52. Chop string in chunks of given size 53. Deep flatten object 54. Restrict modifications of objects 55. Merge objects © JavaScript Interview Guide | learnersbucket.com 7 56. Implement browser history 57. Singleton design pattern 58. Observer design pattern 59. Implement groupBy() method 60. Compare two array or object 61. Array iterator 62. Array with event listeners 63. Filter array of objects on value or index 64. Aggregate array of objects on the given key 65. Convert entity relation array to ancestry tree string 66. Get object value from string path 67. Set object value on string path 68. Polyfill for JSON.stringify() 69. Polyfill for JSON.parse() 70. HTML encoding of the string 71. CSS selector generator 72. Aggregate the input values 73. Fetch request and response Interceptors 74. Cache API call with expiry time 75. Polyfill for getElementByClassName() 76. Polyfill for getElementByClassNameHierarchy() 77. Find the element with the given color property 78. Throttle an array of tasks 79. Decode a string 80. Trie data structure 81. First and last occurrence of a number in the sorted array 82. Piping function - part 1 83. Piping function - part 2 84. Create analytics SDK 85. Check if given binary tree is full 86. Get height and width of a binary tree 87. Polyfill for extend 88. Animate elements in sequence © JavaScript Interview Guide | learnersbucket.com 8 89. Localstorage with expiry 90. Custom cookie 91. Create an immutability helper - part 1 92. Create an immutability helper - part 2 93. Make high priority API call 94. Convert JSON to HTML 95. Convert HTML to JSON 96. Concurrent history tracking system 97. Implement an in-memory search engine 98. Implement a fuzzy search function 99. Cancel an API request 100. Highlight words in the string React Questions 1. usePrevious() hook 2. useIdle() hook 3. useAsync() hook 4. useDebounce() hook 5. useThrottle() hook 6. useResponsive() hook 7. useWhyDidYouUpdate() hook 8. useOnScreen() hook 9. useScript() hook 10. useOnClickOutside() hook 11. useHasFocus() hook 12. useToggle() hook 13. useCopy() hook 14. useLockedBody() hook 15. Number Increment counter 16. Capture product visible in viewport 17. Highlight text on selection 18. Batch API calls in sequence © JavaScript Interview Guide | learnersbucket.com 9 19. Time in human readable format 20. Detect overlapping circles System design Questions 1. Maker checker flow 2. Online coding judge "JavaScript Interview Guide" is a one of its kind resource written specifically for JavaScript developers who are looking to crack the Web, Mobile, Nodejs, or any job interview that requires JavaScript as the primary programming language.