| # | title | topic | type | difficulty |
|---|---|---|---|---|
| 121 | Pull values out with destructuring | Destructuring | Coding | Easy |
| 122 | Count an object's keys | Objects | Coding | Easy |
| 123 | Merge in defaults with spread | Objects | Coding | Easy |
| 124 | Sum 1 to n with a for loop | Loops | Coding | Easy |
| 125 | Countdown with while | Loops |
| Coding |
| Easy |
| 126 | Extract the hostname | URL & Web APIs | Coding | Easy |
| 127 | The safe way to show user text | Security | Multiple choice | Easy |
| 128 | typeof narrowing 101 | TypeScript | Multiple choice | Easy |
| 129 | Format a price with toFixed | Floating Point | Coding | Easy |
| 130 | Dollars to cents, safely | Payments | Coding | Easy |
| 131 | A Proxy with no traps | Proxy & Reflect | Multiple choice | Easy |
| 132 | Turning strict mode on | Strict Mode | Multiple choice | Easy |
| 133 | A closure remembers | YDKJS Book | Multiple choice | Easy |
| 134 | NaN is not NaN | WTF Quirks | Multiple choice | Easy |
| 135 | Sort numbers correctly | Sorting Algorithms | Coding | Easy |
| 136 | Reverse a string | Interview Classics | Coding | Easy |
| 137 | Palindrome check | Interview Classics | Coding | Easy |
| 138 | FizzBuzz, the classic | Algorithms & Recursion | Coding | Easy |
| 139 | Spot the anti-pattern: == everywhere | Patterns & Performance | Multiple choice | Easy |
| 140 | Spot the anti-pattern: var in 2026 | Patterns & Performance | Multiple choice | Easy |
| 141 | Copy or alias? | Patterns & Performance | Multiple choice | Easy |
| 142 | The accidentally quadratic accumulator | Patterns & Performance | Multiple choice | Medium |
| 143 | Kill the O(n²) lookup | Patterns & Performance | Coding | Medium |
| 144 | Plain object or Map? | Patterns & Performance | Multiple choice | Medium |
| 145 | Hidden classes: the shape game | Patterns & Performance | Multiple choice | Hard |
| 146 | Four duplicates checks, one is optimal | Patterns & Performance | Multiple choice | Hard |
| 147 | Order-preserving dedupe at scale | Patterns & Performance | Coding | Hard |
| 148 | The lazy singleton pattern | Patterns & Performance | Coding | Hard |
| 149 | Observer pattern with unsubscribe | Patterns & Performance | Coding | Medium |
| 150 | Prototype pattern: share the methods | Patterns & Performance | Coding | Medium |