JavaScript Coding Questions

As a Front-End developer, JavaScript is the core skill of everything

• 1. implement curry()JavaScripteasy29866 accepted
• 3. implement Array.prototype.flat()JavaScriptmedium23003 accepted
• 4. implement basic throttle()JavaScriptLodashmedium16757 accepted
• 6. implement basic debounce()JavaScriptLodasheasy16147 accepted
• 19. find corresponding node in two identical DOM treeJavaScripteasy10320 accepted
• 16. create an Event EmitterJavaScriptmedium10208 accepted
• 11. what is Composition? create a pipe()JavaScripteasy9103 accepted
• 2. implement curry() with placeholder supportJavaScriptmedium8628 accepted
• 17. Create a simple store for DOM elementJavaScripteasy7945 accepted
• 14. Implement a general memoization function - `memo()`JavaScriptmedium7879 accepted
• 32. implement `Promise.all()`JavaScriptmedium7764 accepted
• 18. Improve a functionJavaScripteasy7107 accepted
• 28. implement clearAllTimeout()JavaScripteasy6842 accepted
• 8. can you shuffle() an array?JavaScriptmedium6837 accepted
• 176. undefined to nullJavaScriptmedium6498 accepted
• 23. create a sum()JavaScriptmedium6174 accepted
• 7. implement debounce() with leading & trailing optionJavaScriptLodashmedium6039 accepted
• 9. decode messageJavaScriptmedium5926 accepted
• 10. first bad versionJavaScriptAlgorithmmedium5775 accepted
• 5. implement throttle() with leading & trailing optionJavaScriptLodashmedium5768 accepted
• 167. Intersection of unsorted arraysJavaScriptAlgorithmeasy5551 accepted
• 58. get DOM tree heightJavaScriptAlgorithmDOMmedium5276 accepted
• 151. implement Array.prototype.map()JavaScriptmedium5134 accepted
• 15. implement a simple DOM wrapper to support method chaining like jQueryJavaScripteasy4898 accepted
• 25. Reorder array with new indexesJavaScriptAlgorithmeasy4866 accepted
• 162. find the single integerJavaScriptAlgorithmeasy4713 accepted
• 35. implement `Promise.race()`JavaScripteasy4264 accepted
• 155. create a count functionJavaScripteasy4237 accepted
• 33. implement `Promise.allSettled()`JavaScriptmedium4206 accepted
• 29. implement async helper - `sequence()`JavaScriptmedium4186 accepted
• 159. implement promisify()JavaScripteasy4089 accepted
• 34. implement `Promise.any()`JavaScriptmedium4046 accepted
• 64. auto-retry Promise on rejectionJavaScriptmedium3943 accepted
• 148. create a counter objectJavaScripteasy3798 accepted
• 92. throttle PromisesJavaScriptmedium3722 accepted
• 113. Virtual DOM IJavaScriptAlgorithmDOMmedium3700 accepted
• 161. toBe() or not.toBe()JavaScriptmedium3403 accepted
• 13. Implement a Queue by using StackJavaScriptAlgorithmmedium3282 accepted
• 154. Two-way bindingJavaScriptDOMeasy3187 accepted
• 39. implement range()JavaScripteasy2983 accepted
• 104. Traverse DOM level by levelJavaScriptAlgorithmDOMmedium2963 accepted
• 57. create an ObservableJavaScriptmedium2950 accepted
• 146. implement Array.prototype.reduce()JavaScriptmedium2950 accepted
• 68. get DOM tagsJavaScriptAlgorithmDOMmedium2883 accepted
• 91. invert a binary treeJavaScriptAlgorithmeasy2839 accepted
• 67. create your own PromiseJavaScriptmedium2757 accepted
• 30. implement async helper - `parallel()`JavaScriptmedium2702 accepted
• 20. Detect data type in JavaScriptJavaScriptmedium2643 accepted
• 26. implement Object.assign()JavaScriptmedium2623 accepted
• 89. Next Right SiblingJavaScriptDOMeasy2605 accepted
• 12. implement Immutability helperJavaScriptmedium2593 accepted
• 157. semver compareJavaScripteasy2584 accepted
• 37. implement Binary Search (unique)JavaScripteasy2528 accepted
• 168. move zerosJavaScriptAlgorithmmedium2514 accepted
• 46. implement `_.once()`JavaScriptLodashmedium2415 accepted
• 60. create your own `new` operatorJavaScripteasy2398 accepted
• 63. create `_.cloneDeep()`JavaScriptAlgorithmLodashmedium2395 accepted
• 110. serialize and deserialize binary treeJavaScriptAlgorithmmedium2387 accepted
• 31. implement async helper - `race()`JavaScripteasy2384 accepted
• 47. reverse a linked listJavaScriptAlgorithmeasy2279 accepted
• 145. most frequently occurring characterJavaScripteasy2170 accepted
• 21. implement JSON.stringify()JavaScripthard?2162 accepted
• 40. implement Bubble SortJavaScriptAlgorithmeasy2161 accepted
• 56. call APIs with paginationJavaScriptmedium2150 accepted
• 85. implement `_.get()`JavaScriptLodashmedium2042 accepted
• 61. create your own `Function.prototype.call`JavaScriptmedium2021 accepted
• 133. roman numerals to integerJavaScripteasy2006 accepted
• 118. Virtual DOM II - createElementJavaScripteasy2004 accepted
• 125. implement classNames()JavaScriptmedium1961 accepted
• 163. integer to roman numeralsJavaScriptAlgorithmeasy1931 accepted
• 103. implement Math.sqrt()JavaScriptAlgorithmmedium1927 accepted
• 123. implement Promise.prototype.finally()JavaScriptmedium1918 accepted
• 69. implement deep equal `_.isEqual()`JavaScriptLodashmedium1890 accepted
• 81. merge sorted arraysJavaScriptAlgorithmeasy1806 accepted
• 107. Find the largest differenceJavaScriptAlgorithmeasy1782 accepted
• 121. A number sequence JavaScripteasy1782 accepted
• 105. find the first duplicate character in a stringJavaScriptstringeasy1756 accepted
• 83. create an intervalJavaScriptmedium1729 accepted
• 38. implement `jest.spyOn()`JavaScripteasy1686 accepted
• 130. create LazyMan()JavaScriptmedium1653 accepted
• 173. uncompress stringJavaScriptstringalgorithmmedium1631 accepted
• 102. validate string of parenthesesJavaScriptAlgorithmstringeasy1617 accepted
• 158. Previous Left SiblingJavaScriptDOMmedium1605 accepted
• 106. Find two numbers that sum up to 0JavaScriptAlgorithmeasy1603 accepted
• 120. create `isPrime()`JavaScriptAlgorithmeasy1602 accepted
• 94. implement your own `Object.create`JavaScripteasy1594 accepted
• 48. search first index with Binary Search(possible duplicate array)JavaScriptAlgorithmeasy1589 accepted
• 138. Intersection of two sorted arraysJavaScriptAlgorithmeasy1582 accepted
• 53. write your own `extends` in es5JavaScriptmedium1565 accepted
• 87. longest substring with unique charactersJavaScriptAlgorithmeasy1544 accepted
• 122. implement memoizeOne()JavaScriptmedium1515 accepted
• 131. implement _.chunk()JavaScriptLodashmedium1510 accepted
• 140. Virtual DOM III - Functional ComponentJavaScripteasy1491 accepted
• 86. Generate Fibonacci NumberJavaScriptAlgorithmmedium1475 accepted
• 54. flatten ThunkJavaScripteasy1474 accepted
• 97. compress a stringJavaScriptstringeasy1433 accepted
• 66. remove duplicates from an arrayJavaScriptAlgorithmmedium1374 accepted
• 109. implement `Math.pow()`JavaScriptAlgorithmeasy1329 accepted
• 116. implement Object.is()JavaScripteasy1328 accepted
• 49. search last index with Binary Search(possible duplicate array)JavaScriptAlgorithmeasy1303 accepted
• 156. implement `_.set()`JavaScriptLodashmedium1298 accepted
• 36. create a fake timer(setTimeout)JavaScriptmedium1272 accepted
• 42. implement Insertion SortJavaScriptAlgorithmeasy1264 accepted
• 135. localStorage with expirationJavaScriptmedium1245 accepted
• 65. add comma to numberJavaScriptmedium1239 accepted
• 24. create a Priority Queue in JavaScriptJavaScriptAlgorithmmedium1230 accepted
• 152. Find Top k ElementsJavaScriptAlgorithmmedium1224 accepted
• 59. create a browser historyJavaScriptmedium1220 accepted
• 90. write your own `instanceof`JavaScriptmedium1211 accepted
• 147. Pick up stonesJavaScripteasy1192 accepted
• 93. Generate Fibonacci Number with recursionJavaScripteasy1183 accepted
• 100. detect circle in linked listJavaScriptAlgorithmeasy1154 accepted
• 55. highlight keywords in HTML stringJavaScriptAlgorithmmedium1152 accepted
• 43. implement Quick SortJavaScriptAlgorithmmedium1131 accepted
• 22. implement JSON.parse()JavaScriptmedium1120 accepted
• 27. implement completeAssign() JavaScriptmedium1099 accepted
• 44. implement Selection SortJavaScriptAlgorithmeasy1084 accepted
• 41. implement Merge SortJavaScriptAlgorithmmedium1077 accepted
• 50. search element right before target with Binary Search(possible duplicate array)JavaScriptAlgorithmeasy1064 accepted
• 101. merge identical API callsJavaScriptmedium1064 accepted
• 139. implement _.partial()JavaScriptLodashmedium1045 accepted
• 52. create a middleware systemJavaScriptmedium1021 accepted
• 82. find available meeting slotsJavaScriptAlgorithmmedium964 accepted
• 79. convert snake_case to camelCaseJavaScriptmedium959 accepted
• 95. implement String.prototype.trim()JavaScriptmedium958 accepted
• 170. Generate CSS Selector for target elementJavaScriptmedium934 accepted
• 51. search element right after target with Binary Search(possible duplicate array)JavaScriptAlgorithmeasy928 accepted
• 96. count "1" in binary formJavaScripteasy870 accepted
• 88. support negative Array index in JavaScriptJavaScriptmedium856 accepted
• 45. find the K-th largest element in an unsorted arrayJavaScriptAlgorithmmedium848 accepted
• 166. validate number stringJavaScriptAlgorithmstringmedium847 accepted
• 62. implement BigInt additionJavaScriptAlgorithmeasy839 accepted
• 117. event delegationJavaScriptmedium808 accepted
• 136. find median of two sorted arrayJavaScriptAlgorithmmedium794 accepted
• 149. interpolationJavaScriptmedium788 accepted
• 111. Count palindromic substringsJavaScriptAlgorithmstringmedium722 accepted
• 108. Implement a Stack by using QueueJavaScriptAlgorithmmedium704 accepted
• 132. the angle between hour hand and minute hand of a clockJavaScriptmedium691 accepted
• 142. lit-html 1 - tagged templatesJavaScriptlit-htmleasy689 accepted
• 119. create a tokenizerJavaScriptmedium654 accepted
• 177. Implement Object.groupBy()JavaScriptmedium654 accepted
• 112. remove duplicate characters in a stringJavaScriptAlgorithmstringmedium615 accepted
• 134. create your own CookieJavaScriptmedium605 accepted
• 153. uglify CSS class namesJavaScriptmedium594 accepted
• 172. implement `Math.clz32()`JavaScriptmedium589 accepted
• 70. implement Observable.from()JavaScriptmedium580 accepted
• 80. implement your own URLSearchParamsJavaScripthard?572 accepted
• 84. create a fake timer (setInterval)JavaScriptmedium536 accepted
• 137. binary tree vertical traversalJavaScriptAlgorithmhard?524 accepted
• 71. implement Observable SubjectJavaScriptmedium521 accepted
• 99. extract all anchor element from HTML string JavaScriptmedium490 accepted
• 171. create callback on message channelJavaScriptmedium489 accepted
• 72. implement Observable interval()JavaScripteasy481 accepted
• 164. implement Immer produce()JavaScriptmedium468 accepted
• 75. implement BigInt subtractionJavaScriptAlgorithmmedium459 accepted
• 74. implement Observable Transformation OperatorsJavaScripteasy435 accepted
• 73. implement Observable fromEvent()JavaScripteasy415 accepted
• 98. validate an IP addressJavaScriptmedium396 accepted
• 169. LRU - Chrome storage automatic evictionJavaScriptAlgorithmmedium376 accepted
• 78. convert HEX color to RGBAJavaScriptmedium335 accepted
• 143. Virtual DOM IV - JSX 1JavaScriptmedium309 accepted
• 141. implement btoa()JavaScripteasy275 accepted
• 124. calculate arithmetic expressionJavaScriptAlgorithmmedium242 accepted
• 76. implement BigInt addition with signJavaScriptmedium211 accepted
• 160. implement atob()JavaScriptmedium198 accepted
• 114. implement BigInt multiplicationJavaScriptmedium169 accepted
• 144. serialize and deserialize data types not supported in JSONJavaScriptmedium169 accepted
• 150. Virtual DOM V - JSX 2JavaScriptmedium163 accepted
• 77. implement BigInt subtraction with signJavaScriptmedium127 accepted
• 115. implement BigInt divisionJavaScriptmedium82 accepted
• 126. BigDecimal additionJavaScriptAlgorithmmedium78 accepted
• 174. CSS Grid Layout auto-placement algorithm - sparseJavaScriptCSShard?53 accepted
• 128. BigDecimal multiplicationJavaScriptAlgorithmmedium42 accepted
• 129. BigDecimal DivisionJavaScriptAlgorithmmedium41 accepted
• 127. BigDecimal subtractionJavaScriptAlgorithmmedium36 accepted
• 175. CSS Grid Layout auto-placement algorithm - denseJavaScriptCSSmedium17 accepted