| # | title | topic | type | difficulty |
|---|---|---|---|---|
| 91 | Group transactions — approach 2: reduce(), no Object.groupBy | Objects | Coding | Hard |
| 92 | Tokenizer — approach 2: classic loops, no array methods | Arrays | Coding | Medium |
| 93 | Grid validation — approach 2: nested for loops | Arrays | Coding | Medium |
| 94 | Function composition — approach 2: a plain loop | Arrays | Coding | Medium |
| 95 | null >= 0 but null != 0 |
| Type Coercion |
| Multiple choice |
| Hard |
| 96 | The army of things equal to nothing | Type Coercion | Multiple choice | Hard |
| 97 | '10' < '9' — string comparison traps | Type Coercion | Multiple choice | Hard |
| 98 | {} + [] — position is everything | Type Coercion | Multiple choice | Hard |
| 99 | Symbols: explicit yes, implicit never | Type Coercion | Multiple choice | Hard |
| 100 | Loose equality is not transitive | Type Coercion | Multiple choice | Hard |
| 101 | Make c == 1 && c == 2 && c == 3 true | Type Coercion | Coding | Hard |
| 102 | The closure-in-a-loop bug, as code | YDKJS Book | Coding | Hard |
| 103 | createSpy — the test-double HOF | YDKJS Book | Coding | Hard |
| 104 | Multi-argument memoize (a Map trie) | YDKJS Book | Coding | Hard |
| 105 | Breadth-first search: shortest path | Algorithms & Recursion | Coding | Hard |
| 106 | Depth-first search: recursive traversal | Algorithms & Recursion | Coding | Medium |
| 107 | Binary search (and where to insert) | Algorithms & Recursion | Coding | Hard |
| 108 | Head recursion vs tail recursion | Algorithms & Recursion | Coding | Hard |
| 109 | Insane Fibonacci: fib(78), recursively, in 2 seconds | Algorithms & Recursion | Coding | Hard |
| 110 | Insane FizzBuzz: no if, no ternary, no switch | Algorithms & Recursion | Coding | Hard |
| 111 | Double every number | Arrays | Coding | Easy |
| 112 | Keep only the evens | Arrays | Coding | Easy |
| 113 | First negative number | Arrays | Coding | Easy |
| 114 | Make a CSV line | Arrays | Coding | Easy |
| 115 | + concatenates, - calculates | Type Coercion | Multiple choice | Easy |
| 116 | Truthy or falsy? | Type Coercion | Multiple choice | Easy |
| 117 | typeof, the basics | Quiz: JS Questions | Multiple choice | Easy |
| 118 | What const actually locks | Quiz: JS Questions | Multiple choice | Easy |
| 119 | floor, ceil, round | Math | Multiple choice | Easy |
| 120 | Clamp a number to a range | Math | Coding | Easy |