The Must-Solve 150.
Every question is a real implementation, debugging or architecture task. Work through the levels in order, or jump straight to what your next interview needs.
10 of 150 questions
Medium
75 questions, 25–45 minutes each
Implement, then defend your edge cases, performance and tests.
JavaScript utilities & FP
debounce, throttle, curry, deep clone, LRU — the utility belt of senior rounds.
- 26Implement debounce() with
cancel()andflush()Free - 27Implement
throttle()with leading and trailing options - 28Implement
curry()supporting partial application - 29Implement
compose()andpipe() - 30Implement deep clone with circular references,
Map,Set, andDate - 31Implement
memoize()with custom cache keys - 32Implement an EventEmitter with
on,off,emit, andonce - 33Implement an LRU cache
- 34Implement an
EventTarget-style custom event system - 35Implement
JSON.stringify()for common data types and edge cases