JavaScript Coding Questions

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

Sort: most accepted Difficulty: medium

4. implement basic throttle()JavaScript Lodash medium
10146 accepted
16. create an Event Emitter JavaScript medium
6754 accepted
2. implement curry() with placeholder support JavaScript medium
5067 accepted
14. Implement a general memoization function - `memo()`JavaScript medium
4915 accepted
32. implement `Promise.all()`JavaScript medium
4376 accepted
58. get DOM tree height JavaScript Algorithm DOM medium
3987 accepted
7. implement debounce() with leading & trailing option JavaScript Lodash medium
3526 accepted
10. first bad version JavaScript Algorithm medium
3497 accepted
9. decode message JavaScript medium
3484 accepted
151. implement Array.prototype.map()JavaScript medium
3448 accepted
5. implement throttle() with leading & trailing option JavaScript Lodash medium
3431 accepted
113. Virtual DOM I JavaScript Algorithm DOM medium
2635 accepted
159. implement promisify()JavaScript medium
2614 accepted
33. implement `Promise.allSettled()`JavaScript medium
2523 accepted
29. implement async helper - `sequence()`JavaScript medium
2452 accepted
34. implement `Promise.any()`JavaScript medium
2384 accepted
161. toBe() or not.toBe()JavaScript medium
2364 accepted
68. get DOM tags JavaScript Algorithm DOM medium
2244 accepted
92. throttle Promises JavaScript medium
2138 accepted
64. auto-retry Promise on rejection JavaScript medium
1957 accepted
13. Implement a Queue by using Stack JavaScript Algorithm medium
1894 accepted
57. create an Observable JavaScript medium
1888 accepted
146. implement Array.prototype.reduce()JavaScript medium
1829 accepted
110. serialize and deserialize binary tree JavaScript Algorithm medium
1813 accepted
26. implement Object.assign()JavaScript medium
1686 accepted
67. create your own Promise JavaScript medium
1678 accepted
30. implement async helper - `parallel()`JavaScript medium
1561 accepted
12. implement Immutability helper JavaScript medium
1540 accepted
20. Detect data type in JavaScript JavaScript medium
1514 accepted
63. create `_.cloneDeep()`JavaScript Algorithm Lodash medium
1486 accepted
21. implement JSON.stringify()JavaScript medium
1390 accepted
56. call APIs with pagination JavaScript medium
1386 accepted
46. implement `_.once()`JavaScript Lodash medium
1343 accepted
123. implement Promise.prototype.finally()JavaScript medium
1313 accepted
158. Previous Left Sibling JavaScript DOM medium
1309 accepted
168. move zeros JavaScript Algorithm medium
1301 accepted
61. create your own `Function.prototype.call`JavaScript medium
1280 accepted
53. write your own `extends` in es5 JavaScript medium
1120 accepted
122. implement memoizeOne()JavaScript medium
1093 accepted
130. create LazyMan()JavaScript medium
1076 accepted
125. implement classNames()JavaScript medium
1076 accepted
103. implement Math.sqrt()JavaScript Algorithm medium
1072 accepted
131. implement _.chunk()JavaScript Lodash medium
1066 accepted
69. implement deep equal `_.isEqual()`JavaScript Lodash medium
1029 accepted
85. implement `_.get()`JavaScript Lodash medium
1001 accepted
97. compress a string JavaScript string medium
986 accepted
66. remove duplicates from an array JavaScript Algorithm medium
947 accepted
36. create a fake timer(setTimeout)JavaScript medium
911 accepted
152. Find Top k Elements JavaScript Algorithm medium
904 accepted
156. implement `_.set()`JavaScript Lodash medium
898 accepted
55. highlight keywords in HTML string JavaScript Algorithm medium
850 accepted
22. implement JSON.parse()JavaScript medium
820 accepted
90. write your own `instanceof`JavaScript medium
819 accepted
65. add comma to number JavaScript medium
815 accepted
24. create a Priority Queue in JavaScript JavaScript Algorithm medium
809 accepted
59. create a browser history JavaScript medium
803 accepted
135. localStorage with expiration JavaScript medium
748 accepted
43. implement Quick Sort JavaScript Algorithm medium
722 accepted
139. implement _.partial()JavaScript Lodash medium
718 accepted
83. create an interval JavaScript medium
710 accepted
101. merge identical API calls JavaScript medium
708 accepted
79. convert snake_case to camelCase JavaScript medium
692 accepted
52. create a middleware system JavaScript medium
688 accepted
95. implement String.prototype.trim()JavaScript medium
668 accepted
149. interpolation JavaScript medium
638 accepted
41. implement Merge Sort JavaScript Algorithm medium
634 accepted
117. event delegation JavaScript medium
625 accepted
82. find available meeting slots JavaScript Algorithm medium
612 accepted
170. Generate CSS Selector for target element JavaScript medium
611 accepted
88. support negative Array index in JavaScript JavaScript medium
601 accepted
132. the angle between hour hand and minute hand of a clock JavaScript medium
555 accepted
136. find median of two sorted array JavaScript Algorithm medium
551 accepted
45. find the K-th largest element in an unsorted array JavaScript Algorithm medium
536 accepted
111. Count palindromic substrings JavaScript Algorithm string medium
502 accepted
166. validate number string JavaScript Algorithm string medium
500 accepted
108. Implement a Stack by using Queue JavaScript Algorithm medium
490 accepted
173. uncompress string JavaScript string algorithm medium
487 accepted
153. uglify CSS class names JavaScript medium
475 accepted
119. create a tokenizer JavaScript medium
474 accepted
112. remove duplicate characters in a string JavaScript Algorithm string medium
467 accepted
70. implement Observable.from()JavaScript medium
419 accepted
84. create a fake timer (setInterval)JavaScript medium
405 accepted
134. create your own Cookie JavaScript medium
377 accepted
99. extract all anchor element from HTML string JavaScript medium
376 accepted
172. implement `Math.clz32()`JavaScript medium
375 accepted
71. implement Observable Subject JavaScript medium
351 accepted
164. implement Immer produce()JavaScript medium
316 accepted
75. implement BigInt subtraction JavaScript Algorithm medium
291 accepted
98. validate an IP address JavaScript medium
290 accepted
171. create callback on message channel JavaScript medium
260 accepted
78. convert HEX color to RGBA JavaScript medium
220 accepted
169. LRU - Chrome storage automatic eviction JavaScript Algorithm medium
214 accepted
143. Virtual DOM IV - JSX 1 JavaScript medium
210 accepted
124. calculate arithmetic expression JavaScript Algorithm medium
158 accepted
160. implement atob()JavaScript medium
134 accepted
76. implement BigInt addition with sign JavaScript medium
127 accepted
144. serialize and deserialize data types not supported in JSON JavaScript medium
120 accepted
150. Virtual DOM V - JSX 2 JavaScript medium
98 accepted
114. implement BigInt multiplication JavaScript medium
95 accepted
77. implement BigInt subtraction with sign JavaScript medium
75 accepted
115. implement BigInt division JavaScript medium
44 accepted
126. BigDecimal addition JavaScript Algorithm medium
42 accepted
129. BigDecimal Division JavaScript Algorithm medium
27 accepted
128. BigDecimal multiplication JavaScript Algorithm medium
20 accepted