JavaScript Coding Questions

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

• 1. implement curry()JavaScripteasy32629 accepted
• 3. implement Array.prototype.flat()JavaScriptmedium24386 accepted
• 4. implement basic throttle()JavaScriptLodashmedium17915 accepted
• 6. implement basic debounce()JavaScriptLodasheasy17596 accepted
• 19. find corresponding node in two identical DOM treeJavaScripteasy10749 accepted
• 16. create an Event EmitterJavaScriptmedium10709 accepted
• 11. what is Composition? create a pipe()JavaScripteasy9953 accepted
• 2. implement curry() with placeholder supportJavaScriptmedium9295 accepted
• 17. Create a simple store for DOM elementJavaScripteasy8416 accepted
• 32. implement `Promise.all()`JavaScriptmedium8406 accepted
• 14. Implement a general memoization function - `memo()`JavaScriptmedium8395 accepted
• 18. Improve a functionJavaScripteasy7633 accepted
• 8. can you shuffle() an array?JavaScriptmedium7456 accepted
• 28. implement clearAllTimeout()JavaScripteasy7241 accepted
• 176. undefined to nullJavaScripteasy6762 accepted
• 23. create a sum()JavaScriptmedium6572 accepted
• 7. implement debounce() with leading & trailing optionJavaScriptLodashmedium6445 accepted
• 9. decode messageJavaScriptmedium6325 accepted
• 5. implement throttle() with leading & trailing optionJavaScriptLodashmedium6184 accepted
• 10. first bad versionJavaScriptAlgorithmmedium6148 accepted
• 167. Intersection of unsorted arraysJavaScriptAlgorithmeasy5660 accepted
• 58. get DOM tree heightJavaScriptAlgorithmDOMmedium5460 accepted
• 151. implement Array.prototype.map()JavaScriptmedium5360 accepted
• 25. Reorder array with new indexesJavaScriptAlgorithmeasy5300 accepted
• 15. implement a simple DOM wrapper to support method chaining like jQueryJavaScripteasy5280 accepted
• 162. find the single integerJavaScriptAlgorithmeasy4827 accepted
• 35. implement `Promise.race()`JavaScripteasy4704 accepted
• 33. implement `Promise.allSettled()`JavaScriptmedium4591 accepted
• 29. implement async helper - `sequence()`JavaScriptmedium4569 accepted
• 34. implement `Promise.any()`JavaScriptmedium4413 accepted
• 155. create a count functionJavaScripteasy4366 accepted
• 64. auto-retry Promise on rejectionJavaScriptmedium4345 accepted
• 159. implement promisify()JavaScripteasy4256 accepted
• 92. throttle PromisesJavaScriptmedium4030 accepted
• 148. create a counter objectJavaScripteasy3946 accepted
• 113. Virtual DOM IJavaScriptAlgorithmDOMmedium3849 accepted
• 13. Implement a Queue by using StackJavaScriptAlgorithmmedium3543 accepted
• 161. toBe() or not.toBe()JavaScriptmedium3523 accepted
• 154. Two-way bindingJavaScriptDOMeasy3254 accepted
• 39. implement range()JavaScripteasy3249 accepted
• 146. implement Array.prototype.reduce()JavaScriptmedium3108 accepted
• 57. create an ObservableJavaScriptmedium3106 accepted
• 104. Traverse DOM level by levelJavaScriptAlgorithmDOMmedium3034 accepted
• 68. get DOM tagsJavaScriptAlgorithmDOMmedium2983 accepted
• 91. invert a binary treeJavaScriptAlgorithmeasy2967 accepted
• 30. implement async helper - `parallel()`JavaScriptmedium2942 accepted
• 20. Detect data type in JavaScriptJavaScriptmedium2921 accepted
• 67. create your own PromiseJavaScriptmedium2878 accepted
• 26. implement Object.assign()JavaScriptmedium2854 accepted
• 12. implement Immutability helperJavaScriptmedium2798 accepted
• 37. implement Binary Search (unique)JavaScripteasy2742 accepted
• 89. Next Right SiblingJavaScriptDOMeasy2693 accepted
• 157. semver compareJavaScripteasy2654 accepted
• 31. implement async helper - `race()`JavaScripteasy2619 accepted
• 46. implement `_.once()`JavaScriptLodashmedium2612 accepted
• 63. create `_.cloneDeep()`JavaScriptAlgorithmLodashmedium2596 accepted
• 168. move zerosJavaScriptAlgorithmmedium2583 accepted
• 60. create your own `new` operatorJavaScripteasy2567 accepted
• 110. serialize and deserialize binary treeJavaScriptAlgorithmmedium2468 accepted
• 47. reverse a linked listJavaScriptAlgorithmeasy2448 accepted
• 40. implement Bubble SortJavaScriptAlgorithmeasy2397 accepted
• 21. implement JSON.stringify()JavaScripthard?2280 accepted
• 145. most frequently occurring characterJavaScripteasy2258 accepted
• 56. call APIs with paginationJavaScriptmedium2257 accepted
• 85. implement `_.get()`JavaScriptLodashmedium2182 accepted
• 61. create your own `Function.prototype.call`JavaScriptmedium2171 accepted
• 118. Virtual DOM II - createElementJavaScripteasy2115 accepted
• 125. implement classNames()JavaScriptmedium2093 accepted
• 133. roman numerals to integerJavaScripteasy2081 accepted
• 69. implement deep equal `_.isEqual()`JavaScriptLodashmedium2073 accepted
• 123. implement Promise.prototype.finally()JavaScriptmedium2031 accepted
• 103. implement Math.sqrt()JavaScriptAlgorithmmedium2012 accepted
• 163. integer to roman numeralsJavaScriptAlgorithmeasy1979 accepted
• 81. merge sorted arraysJavaScriptAlgorithmeasy1938 accepted
• 121. A number sequence JavaScripteasy1871 accepted
• 83. create an intervalJavaScriptmedium1860 accepted
• 107. Find the largest differenceJavaScriptAlgorithmeasy1853 accepted
• 105. find the first duplicate character in a stringJavaScriptstringeasy1846 accepted
• 38. implement `jest.spyOn()`JavaScripteasy1840 accepted
• 130. create LazyMan()JavaScriptmedium1756 accepted
• 48. search first index with Binary Search(possible duplicate array)JavaScriptAlgorithmeasy1746 accepted
• 102. validate string of parenthesesJavaScriptAlgorithmstringeasy1717 accepted
• 173. uncompress stringJavaScriptstringalgorithmmedium1696 accepted
• 94. implement your own `Object.create`JavaScripteasy1695 accepted
• 106. Find two numbers that sum up to 0JavaScriptAlgorithmeasy1685 accepted
• 120. create `isPrime()`JavaScriptAlgorithmeasy1677 accepted
• 53. write your own `extends` in es5JavaScriptmedium1670 accepted
• 87. longest substring with unique charactersJavaScriptAlgorithmeasy1660 accepted
• 138. Intersection of two sorted arraysJavaScriptAlgorithmeasy1655 accepted
• 158. Previous Left SiblingJavaScriptDOMmedium1634 accepted
• 54. flatten ThunkJavaScripteasy1606 accepted
• 122. implement memoizeOne()JavaScriptmedium1585 accepted
• 131. implement _.chunk()JavaScriptLodashmedium1573 accepted
• 140. Virtual DOM III - Functional ComponentJavaScripteasy1572 accepted
• 86. Generate Fibonacci NumberJavaScriptAlgorithmmedium1563 accepted
• 97. compress a stringJavaScriptstringeasy1549 accepted
• 66. remove duplicates from an arrayJavaScriptAlgorithmmedium1475 accepted
• 49. search last index with Binary Search(possible duplicate array)JavaScriptAlgorithmeasy1423 accepted
• 116. implement Object.is()JavaScripteasy1409 accepted
• 109. implement `Math.pow()`JavaScriptAlgorithmeasy1403 accepted
• 42. implement Insertion SortJavaScriptAlgorithmeasy1391 accepted
• 36. create a fake timer(setTimeout)JavaScriptmedium1365 accepted
• 65. add comma to numberJavaScriptmedium1352 accepted
• 24. create a Priority Queue in JavaScriptJavaScriptAlgorithmmedium1350 accepted
• 156. implement `_.set()`JavaScriptLodashmedium1327 accepted
• 135. localStorage with expirationJavaScriptmedium1323 accepted
• 59. create a browser historyJavaScriptmedium1318 accepted
• 90. write your own `instanceof`JavaScriptmedium1267 accepted
• 93. Generate Fibonacci Number with recursionJavaScripteasy1252 accepted
• 152. Find Top k ElementsJavaScriptAlgorithmmedium1241 accepted
• 147. Pick up stonesJavaScripteasy1238 accepted
• 55. highlight keywords in HTML stringJavaScriptAlgorithmmedium1225 accepted
• 43. implement Quick SortJavaScriptAlgorithmmedium1218 accepted
• 100. detect circle in linked listJavaScriptAlgorithmeasy1218 accepted
• 22. implement JSON.parse()JavaScriptmedium1201 accepted
• 44. implement Selection SortJavaScriptAlgorithmeasy1193 accepted
• 27. implement completeAssign() JavaScriptmedium1180 accepted
• 50. search element right before target with Binary Search(possible duplicate array)JavaScriptAlgorithmeasy1174 accepted
• 41. implement Merge SortJavaScriptAlgorithmmedium1166 accepted
• 101. merge identical API callsJavaScriptmedium1142 accepted
• 52. create a middleware systemJavaScriptmedium1114 accepted
• 139. implement _.partial()JavaScriptLodashmedium1093 accepted
• 95. implement String.prototype.trim()JavaScriptmedium1030 accepted
• 82. find available meeting slotsJavaScriptAlgorithmmedium1022 accepted
• 79. convert snake_case to camelCaseJavaScriptmedium1017 accepted
• 51. search element right after target with Binary Search(possible duplicate array)JavaScriptAlgorithmeasy1004 accepted
• 170. Generate CSS Selector for target elementJavaScriptmedium962 accepted
• 96. count "1" in binary formJavaScripteasy936 accepted
• 62. implement BigInt additionJavaScriptAlgorithmeasy914 accepted
• 88. support negative Array index in JavaScriptJavaScriptmedium907 accepted
• 45. find the K-th largest element in an unsorted arrayJavaScriptAlgorithmmedium903 accepted
• 166. validate number stringJavaScriptAlgorithmstringmedium866 accepted
• 117. event delegationJavaScriptmedium850 accepted
• 136. find median of two sorted arrayJavaScriptAlgorithmmedium834 accepted
• 149. interpolationJavaScriptmedium807 accepted
• 111. Count palindromic substringsJavaScriptAlgorithmstringmedium752 accepted
• 177. Implement Object.groupBy()JavaScriptmedium744 accepted
• 108. Implement a Stack by using QueueJavaScriptAlgorithmmedium740 accepted
• 132. the angle between hour hand and minute hand of a clockJavaScriptmedium707 accepted
• 142. lit-html 1 - tagged templatesJavaScriptlit-htmleasy706 accepted
• 119. create a tokenizerJavaScriptmedium689 accepted
• 112. remove duplicate characters in a stringJavaScriptAlgorithmstringmedium641 accepted
• 134. create your own CookieJavaScriptmedium632 accepted
• 153. uglify CSS class namesJavaScriptmedium612 accepted
• 70. implement Observable.from()JavaScriptmedium607 accepted
• 172. implement `Math.clz32()`JavaScriptmedium595 accepted
• 80. implement your own URLSearchParamsJavaScripthard?587 accepted
• 84. create a fake timer (setInterval)JavaScriptmedium570 accepted
• 137. binary tree vertical traversalJavaScriptAlgorithmhard?561 accepted
• 71. implement Observable SubjectJavaScriptmedium549 accepted
• 99. extract all anchor element from HTML string JavaScriptmedium509 accepted
• 72. implement Observable interval()JavaScripteasy506 accepted
• 75. implement BigInt subtractionJavaScriptAlgorithmmedium500 accepted
• 171. create callback on message channelJavaScriptmedium496 accepted
• 164. implement Immer produce()JavaScriptmedium488 accepted
• 74. implement Observable Transformation OperatorsJavaScripteasy451 accepted
• 73. implement Observable fromEvent()JavaScripteasy436 accepted
• 98. validate an IP addressJavaScriptmedium411 accepted
• 169. LRU - Chrome storage automatic evictionJavaScriptAlgorithmmedium389 accepted
• 78. convert HEX color to RGBAJavaScriptmedium356 accepted
• 143. Virtual DOM IV - JSX 1JavaScriptmedium314 accepted
• 141. implement btoa()JavaScripteasy286 accepted
• 124. calculate arithmetic expressionJavaScriptAlgorithmmedium259 accepted
• 76. implement BigInt addition with signJavaScriptmedium236 accepted
• 160. implement atob()JavaScriptmedium200 accepted
• 114. implement BigInt multiplicationJavaScriptmedium179 accepted
• 144. serialize and deserialize data types not supported in JSONJavaScriptmedium176 accepted
• 150. Virtual DOM V - JSX 2JavaScriptmedium167 accepted
• 77. implement BigInt subtraction with signJavaScriptmedium140 accepted
• 115. implement BigInt divisionJavaScriptmedium86 accepted
• 126. BigDecimal additionJavaScriptAlgorithmmedium82 accepted
• 174. CSS Grid Layout auto-placement algorithm - sparseJavaScriptCSShard?59 accepted
• 128. BigDecimal multiplicationJavaScriptAlgorithmmedium46 accepted
• 129. BigDecimal DivisionJavaScriptAlgorithmmedium44 accepted
• 127. BigDecimal subtractionJavaScriptAlgorithmmedium39 accepted
• 175. CSS Grid Layout auto-placement algorithm - denseJavaScriptCSSmedium21 accepted