Front-End coding problems including algorithms and JavaScript ones.

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1. implement curry()JavaScript easy3498 accepted
3. implement Array.prototype.flat()JavaScript medium3082 accepted
4. implement basic throttle()JavaScript Lodash medium2284 accepted
6. implement basic debounce()JavaScript Lodash easy1974 accepted
19. find corresponding node in two identical DOM tree JavaScript medium1763 accepted
16. create an Event Emitter JavaScript medium1584 accepted
32. implement `Promise.all()`JavaScript medium1280 accepted
11. what is Composition? create a pipe()JavaScript easy1273 accepted
17. Create a simple store for DOM element JavaScript easy1192 accepted
58. get DOM tree height JavaScript Algorithm DOM medium1189 accepted
9. decode message JavaScript medium1111 accepted
151. implement Array.prototype.map()JavaScript medium1107 accepted
2. implement curry() with placeholder support JavaScript medium1085 accepted
10. first bad version JavaScript Algorithm medium1080 accepted
8. can you shuffle() an array?JavaScript medium1064 accepted
18. Improve a function JavaScript medium1057 accepted
14. Implement a general memoization function - `memo()`JavaScript medium1021 accepted
28. implement clearAllTimeout()JavaScript easy1001 accepted
23. create a sum()JavaScript medium954 accepted
162. find the single integer JavaScript Algorithm easy910 accepted
7. implement debounce() with leading & trailing option JavaScript Lodash medium871 accepted
148. create a counter object JavaScript easy801 accepted
25. Reorder array with new indexes JavaScript Algorithm medium787 accepted
29. implement async helper - `sequence()`JavaScript medium770 accepted
15. implement a simple DOM wrapper to support method chaining like jQuery JavaScript easy768 accepted
5. implement throttle() with leading & trailing option JavaScript Lodash medium764 accepted
155. create a count function JavaScript easy759 accepted
104. Traverse DOM level by level JavaScript Algorithm DOM medium716 accepted
33. implement `Promise.allSettled()`JavaScript medium675 accepted
159. implement promisify()JavaScript easy647 accepted
64. auto-retry Promise on rejection JavaScript medium644 accepted
35. implement `Promise.race()`JavaScript easy641 accepted
39. implement range()JavaScript easy638 accepted
68. get DOM tags JavaScript Algorithm DOM medium623 accepted
113. Virtual DOM I JavaScript Algorithm DOM medium620 accepted
34. implement `Promise.any()`JavaScript medium601 accepted
92. throttle Promises JavaScript medium592 accepted
57. create an Observable JavaScript medium557 accepted
13. Implement a Queue by using Stack JavaScript Algorithm ByteDance medium553 accepted
89. Next Right Sibling JavaScript DOM Microsoft medium549 accepted
91. invert a binary tree JavaScript Algorithm easy546 accepted
26. implement Object.assign()JavaScript medium539 accepted
146. implement Array.prototype.reduce()JavaScript medium528 accepted
30. implement async helper - `parallel()`JavaScript medium512 accepted
20. Detect data type in JavaScript JavaScript medium512 accepted
161. toBe() or not.toBe()JavaScript medium504 accepted
110. serialize and deserialize binary tree JavaScript Algorithm medium497 accepted
60. create your own `new` operator JavaScript easy487 accepted
145. most frequently occurring character JavaScript easy482 accepted
154. Two-way binding JavaScript DOM easy475 accepted
157. semver compare JavaScript easy474 accepted
47. reverse a linked list JavaScript Algorithm easy468 accepted
37. implement Binary Search (unique)JavaScript easy466 accepted
63. create `_.cloneDeep()`JavaScript Algorithm Lodash medium451 accepted
31. implement async helper - `race()`JavaScript easy450 accepted
46. implement `_.once()`JavaScript Lodash medium449 accepted
138. Intersection of two sorted arrays JavaScript Algorithm easy446 accepted
131. implement _.chunk()JavaScript Lodash medium441 accepted
56. call APIs with pagination JavaScript medium433 accepted
12. implement Immutability helper JavaScript medium427 accepted
67. create your own Promise JavaScript Airbnb medium425 accepted
53. write your own `extends` in es5 JavaScript medium424 accepted
158. Previous Left Sibling JavaScript DOM medium413 accepted
123. implement Promise.prototype.finally()JavaScript medium408 accepted
61. create your own `Function.prototype.call`JavaScript medium405 accepted
107. Find the largest difference JavaScript Algorithm easy395 accepted
152. Find Top k Elements JavaScript Algorithm medium387 accepted
122. implement memoizeOne()JavaScript medium367 accepted
106. Find two numbers that sum up to 0 JavaScript Algorithm easy364 accepted
66. remove duplicates from an array JavaScript Algorithm medium362 accepted
121. A number sequence JavaScript medium361 accepted
120. create `isPrime()`JavaScript Algorithm easy358 accepted
130. create LazyMan()JavaScript medium355 accepted
105. find the first duplicate character in a string JavaScript Apple easy348 accepted
85. implement `_.get()`JavaScript Lodash medium347 accepted
97. compress a string JavaScript medium336 accepted
21. implement JSON.stringify()JavaScript medium334 accepted
103. implement Math.sqrt()JavaScript Algorithm medium332 accepted
69. implement deep equal `_.isEqual()`JavaScript Lodash medium330 accepted
135. localStorage with expiration JavaScript medium324 accepted
24. create a Priority Queue in JavaScript JavaScript Algorithm medium321 accepted
139. implement _.partial()JavaScript Lodash medium313 accepted
55. highlight keywords in HTML string JavaScript Algorithm medium313 accepted
59. create a browser history JavaScript medium312 accepted
38. implement `jest.spyOn()`JavaScript medium310 accepted
133. roman numerals to integer JavaScript easy309 accepted
118. Virtual DOM II - createElement JavaScript medium304 accepted
54. flatten Thunk JavaScript easy304 accepted
93. Generate Fibonacci Number with recursion JavaScript easy300 accepted
94. implement your own `Object.create`JavaScript easy298 accepted
102. validate string of parentheses JavaScript Algorithm easy296 accepted
40. implement Bubble Sort JavaScript Algorithm easy296 accepted
65. add comma to number JavaScript medium289 accepted
125. implement classNames()JavaScript medium288 accepted
86. Generate Fibonacci Number JavaScript Algorithm medium288 accepted
163. integer to roman numerals JavaScript Algorithm easy281 accepted
156. implement `_.set()`JavaScript Lodash medium280 accepted
48. search first index with Binary Search(possible duplicate array)JavaScript Algorithm medium276 accepted
95. implement String.prototype.trim()JavaScript medium273 accepted
81. merge sorted arrays JavaScript Algorithm ByteDance easy272 accepted
90. write your own `instanceof`JavaScript medium268 accepted
83. create an interval JavaScript ByteDance medium263 accepted
109. implement `Math.pow()`JavaScript Algorithm easy261 accepted
100. detect circle in linked list JavaScript Algorithm easy258 accepted
49. search last index with Binary Search(possible duplicate array)JavaScript Algorithm easy256 accepted
36. create a fake timer(setTimeout)JavaScript medium255 accepted
79. convert snake_case to camelCase JavaScript medium254 accepted
88. support negative Array index in JavaScript JavaScript medium244 accepted
52. create a middleware system JavaScript medium239 accepted
140. Virtual DOM III - Functional Component JavaScript medium236 accepted
117. event delegation JavaScript medium225 accepted
147. Pick up stones JavaScript easy218 accepted
136. find median of two sorted array JavaScript Algorithm medium218 accepted
108. Implement a Stack by using Queue JavaScript Algorithm medium216 accepted
51. search element right after target with Binary Search(possible duplicate array)JavaScript Algorithm easy213 accepted
149. interpolation JavaScript medium212 accepted
87. longest substring with unique characters JavaScript Algorithm easy209 accepted
119. create a tokenizer JavaScript medium208 accepted
116. implement Object.is()JavaScript medium208 accepted
27. implement completeAssign() JavaScript medium208 accepted
82. find available meeting slots JavaScript Algorithm Airbnb medium205 accepted
22. implement JSON.parse()JavaScript medium205 accepted
153. uglify CSS class names JavaScript medium203 accepted
101. merge identical API calls JavaScript medium199 accepted
96. count "1" in binary form JavaScript easy199 accepted
42. implement Insertion Sort JavaScript Algorithm easy192 accepted
43. implement Quick Sort JavaScript Algorithm medium191 accepted
50. search element right before target with Binary Search(possible duplicate array)JavaScript Algorithm easy189 accepted
44. implement Selection Sort JavaScript Algorithm easy189 accepted
99. extract all anchor element from HTML string JavaScript medium184 accepted
62. implement BigInt addition JavaScript Algorithm medium175 accepted
41. implement Merge Sort JavaScript Algorithm medium175 accepted
111. Count palindromic substrings JavaScript Algorithm medium170 accepted
80. implement your own URLSearchParams JavaScript hard?164 accepted
70. implement Observable.from()JavaScript medium163 accepted
137. binary tree vertical traversal JavaScript Algorithm hard?161 accepted
112. remove duplicate characters in a string JavaScript Algorithm medium161 accepted
132. the angle between hour hand and minute hand of a clock JavaScript U-NEXT medium160 accepted
45. find the K-th largest element in an unsorted array JavaScript Algorithm medium156 accepted
72. implement Observable interval()JavaScript easy142 accepted
142. lit-html 1 - tagged templates JavaScript lit-html easy140 accepted
98. validate an IP address JavaScript medium124 accepted
71. implement Observable Subject JavaScript medium124 accepted
134. create your own Cookie JavaScript hard?123 accepted
73. implement Observable fromEvent()JavaScript easy121 accepted
84. create a fake timer (setInterval)JavaScript medium116 accepted
74. implement Observable Transformation Operators JavaScript easy116 accepted
78. convert HEX color to RGBA JavaScript medium94 accepted
143. Virtual DOM IV - JSX 1 JavaScript medium89 accepted
75. implement BigInt subtraction JavaScript Algorithm medium84 accepted
124. calculate arithmetic expression JavaScript Algorithm medium78 accepted
144. serialize and deserialize data types not supported in JSON JavaScript medium56 accepted
160. implement atob()JavaScript medium45 accepted
76. implement BigInt addition with sign JavaScript medium40 accepted
141. implement btoa()JavaScript few challengers34 accepted
114. implement BigInt multiplication JavaScript medium29 accepted
164. implement Immer produce()JavaScript hard?23 accepted
77. implement BigInt subtraction with sign JavaScript few challengers21 accepted
150. Virtual DOM V - JSX 2 JavaScript hard?14 accepted
115. implement BigInt division JavaScript few challengers9 accepted
126. BigDecimal addition JavaScript Algorithm few challengers8 accepted
128. BigDecimal multiplication JavaScript Algorithm few challengers7 accepted
129. BigDecimal Division JavaScript Algorithm few challengers4 accepted
127. BigDecimal subtraction JavaScript Algorithm few challengers2 accepted