| # | title | topic | type | difficulty |
|---|---|---|---|---|
| 1 | Double every number | Arrays | Coding | Easy |
| 2 | Keep only the evens | Arrays | Coding | Easy |
| 3 | First negative number | Arrays | Coding | Easy |
| 4 | Make a CSV line | Arrays | Coding | Easy |
| 5 | + concatenates, - calculates | Type Coercion |
| Multiple choice |
| Easy |
| 6 | Truthy or falsy? | Type Coercion | Multiple choice | Easy |
| 7 | typeof, the basics | Quiz: JS Questions | Multiple choice | Easy |
| 8 | What const actually locks | Quiz: JS Questions | Multiple choice | Easy |
| 9 | floor, ceil, round | Math | Multiple choice | Easy |
| 10 | Clamp a number to a range | Math | Coding | Easy |
| 11 | Pull values out with destructuring | Destructuring | Coding | Easy |
| 12 | Count an object's keys | Objects | Coding | Easy |
| 13 | Merge in defaults with spread | Objects | Coding | Easy |
| 14 | Sum 1 to n with a for loop | Loops | Coding | Easy |
| 15 | Countdown with while | Loops | Coding | Easy |
| 16 | Extract the hostname | URL & Web APIs | Coding | Easy |
| 17 | The safe way to show user text | Security | Multiple choice | Easy |
| 18 | typeof narrowing 101 | TypeScript | Multiple choice | Easy |
| 19 | Format a price with toFixed | Floating Point | Coding | Easy |
| 20 | Dollars to cents, safely | Payments | Coding | Easy |
| 21 | A Proxy with no traps | Proxy & Reflect | Multiple choice | Easy |
| 22 | Turning strict mode on | Strict Mode | Multiple choice | Easy |
| 23 | A closure remembers | YDKJS Book | Multiple choice | Easy |
| 24 | NaN is not NaN | WTF Quirks | Multiple choice | Easy |
| 25 | Sort numbers correctly | Sorting Algorithms | Coding | Easy |
| 26 | Reverse a string | Interview Classics | Coding | Easy |
| 27 | Palindrome check | Interview Classics | Coding | Easy |
| 28 | FizzBuzz, the classic | Algorithms & Recursion | Coding | Easy |
| 29 | Spot the anti-pattern: == everywhere | Patterns & Performance | Multiple choice | Easy |
| 30 | Spot the anti-pattern: var in 2026 | Patterns & Performance | Multiple choice | Easy |