| # | title | topic | type | difficulty |
|---|---|---|---|---|
| 61 | [] == ![] | WTF Quirks | Multiple choice | Hard |
| 62 | Comparison chains don't chain | WTF Quirks | Multiple choice | Medium |
| 63 | Math.min() > Math.max() | WTF Quirks | Multiple choice | Medium |
| 64 | Spread and rest, everywhere at once | Quiz: JS Questions | Multiple choice | Medium |
| 65 | Generators talk back |
| Quiz: JS Questions |
| Multiple choice |
| Hard |
| 66 | Symbols hide from everything | Quiz: JS Questions | Multiple choice | Medium |
| 67 | Static methods don't reach instances | Quiz: JS Questions | Multiple choice | Medium |
| 68 | Quicksort from scratch | Sorting Algorithms | Coding | Hard |
| 69 | Merge sort — prove it's stable | Sorting Algorithms | Coding | Hard |
| 70 | Insertion sort, in place | Sorting Algorithms | Coding | Medium |
| 71 | Multi-key sort with a composed comparator | Sorting Algorithms | Coding | Hard |
| 72 | Tagged templates: redact the interpolations | YDKJS Book | Coding | Medium |
| 73 | Two Sum in one pass | Interview Classics | Coding | Medium |
| 74 | LRU cache with O(1) operations | Interview Classics | Coding | Hard |
| 75 | Build an EventEmitter | Interview Classics | Coding | Hard |
| 76 | Balanced brackets with a stack | Interview Classics | Coding | Medium |
| 77 | Longest substring without repeats (sliding window) | Interview Classics | Coding | Hard |
| 78 | Flatten an object to dot-paths (and holes beware) | Interview Classics | Coding | Hard |
| 79 | Trapping rain water (two pointers) | Interview Classics | Coding | Hard |
| 80 | Edit distance (Levenshtein, full DP) | Interview Classics | Coding | Hard |
| 81 | deepClone that preserves cycles | Interview Classics | Coding | Hard |
| 82 | Add numbers too big for Number | Floating Point | Coding | Hard |
| 83 | All permutations, in order | Interview Classics | Coding | Hard |
| 84 | Pair sum — approach 2: classic loops only | Arrays | Coding | Medium |
| 85 | Deep flatten — approach 2: recursion, no .flat() | Arrays | Coding | Medium |
| 86 | Deep max — approach 2: reduce(), Math.max banned | Math | Coding | Medium |
| 87 | Multiplication table — approach 2: nested for loops | Arrays | Coding | Medium |
| 88 | Weighted sum — approach 2: reduce(), no loops | Loops | Coding | Medium |
| 89 | Reverse an integer — approach 2: string methods | Loops | Coding | Medium |
| 90 | Collatz steps — approach 2: pure recursion | Loops | Coding | Medium |