| # | title | topic | type | difficulty |
|---|---|---|---|---|
| 1 | Kill the O(n²) lookup | Patterns & Performance | Coding | Medium |
| 2 | Observer pattern with unsubscribe | Patterns & Performance | Coding | Medium |
| 3 | Prototype pattern: share the methods | Patterns & Performance | Coding | Medium |
| 4 | Mixin pattern: compose behaviors | Patterns & Performance | Coding | Medium |