JavaScript Coding Questions

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

176. undefined to null JavaScript medium
175. CSS Grid Layout auto-placement algorithm - dense JavaScript CSS few challengers
174. CSS Grid Layout auto-placement algorithm - sparse JavaScript CSS few challengers
173. uncompress string JavaScript string algorithm medium
172. implement `Math.clz32()`JavaScript medium
171. create callback on message channel JavaScript medium
170. Generate CSS Selector for target element JavaScript medium
169. LRU - Chrome storage automatic eviction JavaScript Algorithm medium
168. move zeros JavaScript Algorithm medium
167. Intersection of unsorted arrays JavaScript Algorithm easy
166. validate number string JavaScript Algorithm string medium
165. remove characters Algorithm easy
164. implement Immer produce()JavaScript medium
163. integer to roman numerals JavaScript Algorithm easy
162. find the single integer JavaScript Algorithm easy
161. toBe() or not.toBe()JavaScript medium
160. implement atob()JavaScript medium
159. implement promisify()JavaScript medium
158. Previous Left Sibling JavaScript DOM medium
157. semver compare JavaScript easy
156. implement `_.set()`JavaScript Lodash medium
155. create a count function JavaScript easy
154. Two-way binding JavaScript DOM easy
153. uglify CSS class names JavaScript medium
152. Find Top k Elements JavaScript Algorithm medium
151. implement Array.prototype.map()JavaScript medium
150. Virtual DOM V - JSX 2 JavaScript medium
149. interpolation JavaScript medium
148. create a counter object JavaScript easy
147. Pick up stones JavaScript easy
146. implement Array.prototype.reduce()JavaScript medium
145. most frequently occurring character JavaScript easy
144. serialize and deserialize data types not supported in JSON JavaScript medium
143. Virtual DOM IV - JSX 1 JavaScript medium
142. lit-html 1 - tagged templates JavaScript lit-html easy
141. implement btoa()JavaScript easy
140. Virtual DOM III - Functional Component JavaScript easy
139. implement _.partial()JavaScript Lodash medium
138. Intersection of two sorted arrays JavaScript Algorithm easy
137. binary tree vertical traversal JavaScript Algorithm hard?
136. find median of two sorted array JavaScript Algorithm medium
135. localStorage with expiration JavaScript medium
134. create your own Cookie JavaScript medium
133. roman numerals to integer JavaScript easy
132. the angle between hour hand and minute hand of a clock JavaScript medium
131. implement _.chunk()JavaScript Lodash medium
130. create LazyMan()JavaScript medium
129. BigDecimal Division JavaScript Algorithm few challengers
128. BigDecimal multiplication JavaScript Algorithm medium
127. BigDecimal subtraction JavaScript Algorithm few challengers
126. BigDecimal addition JavaScript Algorithm medium
125. implement classNames()JavaScript medium
124. calculate arithmetic expression JavaScript Algorithm medium
123. implement Promise.prototype.finally()JavaScript medium
122. implement memoizeOne()JavaScript medium
121. A number sequence JavaScript easy
120. create `isPrime()`JavaScript Algorithm easy
119. create a tokenizer JavaScript medium
118. Virtual DOM II - createElement JavaScript easy
117. event delegation JavaScript medium
116. implement Object.is()JavaScript easy
115. implement BigInt division JavaScript medium
114. implement BigInt multiplication JavaScript medium
113. Virtual DOM I JavaScript Algorithm DOM medium
112. remove duplicate characters in a string JavaScript Algorithm string medium
111. Count palindromic substrings JavaScript Algorithm string easy
110. serialize and deserialize binary tree JavaScript Algorithm medium
109. implement `Math.pow()`JavaScript Algorithm easy
108. Implement a Stack by using Queue JavaScript Algorithm medium
107. Find the largest difference JavaScript Algorithm easy
106. Find two numbers that sum up to 0 JavaScript Algorithm easy
105. find the first duplicate character in a string JavaScript string easy
104. Traverse DOM level by level JavaScript Algorithm DOM easy
103. implement Math.sqrt()JavaScript Algorithm medium
102. validate string of parentheses JavaScript Algorithm string easy
101. merge identical API calls JavaScript medium
100. detect circle in linked list JavaScript Algorithm easy
99. extract all anchor element from HTML string JavaScript medium
98. validate an IP address JavaScript medium
97. compress a string JavaScript string easy
96. count "1" in binary form JavaScript easy
95. implement String.prototype.trim()JavaScript medium
94. implement your own `Object.create`JavaScript easy
93. Generate Fibonacci Number with recursion JavaScript easy
92. throttle Promises JavaScript medium
91. invert a binary tree JavaScript Algorithm easy
90. write your own `instanceof`JavaScript medium
89. Next Right Sibling JavaScript DOM easy
88. support negative Array index in JavaScript JavaScript medium
87. longest substring with unique characters JavaScript Algorithm easy
86. Generate Fibonacci Number JavaScript Algorithm easy
85. implement `_.get()`JavaScript Lodash medium
84. create a fake timer (setInterval)JavaScript medium
83. create an interval JavaScript medium
82. find available meeting slots JavaScript Algorithm medium
81. merge sorted arrays JavaScript Algorithm easy
80. implement your own URLSearchParams JavaScript hard?
79. convert snake_case to camelCase JavaScript medium
78. convert HEX color to RGBA JavaScript medium
77. implement BigInt subtraction with sign JavaScript easy
76. implement BigInt addition with sign JavaScript medium
75. implement BigInt subtraction JavaScript Algorithm medium
74. implement Observable Transformation Operators JavaScript easy
73. implement Observable fromEvent()JavaScript easy
72. implement Observable interval()JavaScript easy
71. implement Observable Subject JavaScript medium
70. implement Observable.from()JavaScript medium
69. implement deep equal `_.isEqual()`JavaScript Lodash medium
68. get DOM tags JavaScript Algorithm DOM easy
67. create your own Promise JavaScript medium
66. remove duplicates from an array JavaScript Algorithm medium
65. add comma to number JavaScript medium
64. auto-retry Promise on rejection JavaScript medium
63. create `_.cloneDeep()`JavaScript Algorithm Lodash medium
62. implement BigInt addition JavaScript Algorithm easy
61. create your own `Function.prototype.call`JavaScript medium
60. create your own `new` operator JavaScript easy
59. create a browser history JavaScript medium
58. get DOM tree height JavaScript Algorithm DOM medium
57. create an Observable JavaScript medium
56. call APIs with pagination JavaScript medium
55. highlight keywords in HTML string JavaScript Algorithm medium
54. flatten Thunk JavaScript easy
53. write your own `extends` in es5 JavaScript medium
52. create a middleware system JavaScript medium
51. search element right after target with Binary Search(possible duplicate array)JavaScript Algorithm easy
50. search element right before target with Binary Search(possible duplicate array)JavaScript Algorithm easy
49. search last index with Binary Search(possible duplicate array)JavaScript Algorithm easy
48. search first index with Binary Search(possible duplicate array)JavaScript Algorithm easy
47. reverse a linked list JavaScript Algorithm easy
46. implement `_.once()`JavaScript Lodash medium
45. find the K-th largest element in an unsorted array JavaScript Algorithm medium
44. implement Selection Sort JavaScript Algorithm easy
43. implement Quick Sort JavaScript Algorithm medium
42. implement Insertion Sort JavaScript Algorithm easy
41. implement Merge Sort JavaScript Algorithm medium
40. implement Bubble Sort JavaScript Algorithm easy
39. implement range()JavaScript easy
38. implement `jest.spyOn()`JavaScript easy
37. implement Binary Search (unique)JavaScript easy
36. create a fake timer(setTimeout)JavaScript medium
35. implement `Promise.race()`JavaScript easy
34. implement `Promise.any()`JavaScript medium
33. implement `Promise.allSettled()`JavaScript medium
32. implement `Promise.all()`JavaScript medium
31. implement async helper - `race()`JavaScript easy
30. implement async helper - `parallel()`JavaScript medium
29. implement async helper - `sequence()`JavaScript medium
28. implement clearAllTimeout()JavaScript easy
27. implement completeAssign() JavaScript easy
26. implement Object.assign()JavaScript medium
25. Reorder array with new indexes JavaScript Algorithm easy
24. create a Priority Queue in JavaScript JavaScript Algorithm medium
23. create a sum()JavaScript easy
22. implement JSON.parse()JavaScript medium
21. implement JSON.stringify()JavaScript medium
20. Detect data type in JavaScript JavaScript medium
19. find corresponding node in two identical DOM tree JavaScript easy
18. Improve a function JavaScript easy
17. Create a simple store for DOM element JavaScript easy
16. create an Event Emitter JavaScript medium
15. implement a simple DOM wrapper to support method chaining like jQuery JavaScript easy
14. Implement a general memoization function - `memo()`JavaScript medium
13. Implement a Queue by using Stack JavaScript Algorithm medium
12. implement Immutability helper JavaScript medium
11. what is Composition? create a pipe()JavaScript easy
10. first bad version JavaScript Algorithm medium
9. decode message JavaScript medium
8. can you shuffle() an array?JavaScript easy
7. implement debounce() with leading & trailing option JavaScript Lodash medium
6. implement basic debounce()JavaScript Lodash easy
5. implement throttle() with leading & trailing option JavaScript Lodash medium
4. implement basic throttle()JavaScript Lodash medium
3. implement Array.prototype.flat()JavaScript easy
2. implement curry() with placeholder support JavaScript medium
1. implement curry()JavaScript easy