| # | title | topic | type | difficulty |
|---|---|---|---|---|
| 61 | Binary search (and where to insert) | Algorithms & Recursion | Coding | Hard |
| 62 | Head recursion vs tail recursion | Algorithms & Recursion | Coding | Hard |
| 63 | Insane Fibonacci: fib(78), recursively, in 2 seconds | Algorithms & Recursion | Coding | Hard |
| 64 | Insane FizzBuzz: no if, no ternary, no switch | Algorithms & Recursion | Coding | Hard |
| 65 | Hidden classes: the shape game |
| Patterns & Performance |
| Multiple choice |
| Hard |
| 66 | Four duplicates checks, one is optimal | Patterns & Performance | Multiple choice | Hard |
| 67 | Order-preserving dedupe at scale | Patterns & Performance | Coding | Hard |
| 68 | The lazy singleton pattern | Patterns & Performance | Coding | Hard |
| 69 | What triggers a CORS preflight? | Web Platform | Multiple choice | Hard |
| 70 | no-cache does not mean no cache | Web Platform | Multiple choice | Hard |
| 71 | Microtask starvation | Event Loop & Memory | Multiple choice | Hard |
| 72 | Find the leak-proof cache | Event Loop & Memory | Multiple choice | Hard |
| 73 | Drag the output: timers scheduling timers | Event Loop & Memory | Drag & drop | Hard |
| 74 | Test the tester: toCents() | Unit Testing | Write the tests | Hard |
| 75 | Test the tester: range() | Unit Testing | Write the tests | Hard |
| 76 | Test the tester: escapeHtml() | Unit Testing | Write the tests | Hard |
| 77 | Test the tester: LRU cache | Unit Testing | Write the tests | Hard |
| 78 | Test the tester: curry() | Unit Testing | Write the tests | Hard |
| 79 | Test the tester: searchInsert() | Unit Testing | Write the tests | Hard |
| 80 | Test the tester: deepClone() | Unit Testing | Write the tests | Hard |
| 81 | Test the tester: createEmitter() | Unit Testing | Write the tests | Hard |
| 82 | Test the tester: addStrings() | Unit Testing | Write the tests | Hard |
| 83 | Test the tester: memoize() | Unit Testing | Write the tests | Hard |
| 84 | Test the tester: groupBy() | Unit Testing | Write the tests | Hard |
| 85 | Drag the output into order: async/await | Quiz: JS Questions | Drag & drop | Hard |
| 86 | Drag the coercion algorithm into order: [10] == 10 | Type Coercion | Drag & drop | Hard |
| 87 | Coercion flow: [] + {} | Type Coercion | Drag & drop | Hard |
| 88 | Coercion flow: {} + [] (statement position) | Type Coercion | Drag & drop | Hard |
| 89 | Coercion flow: [] == ![] | Type Coercion | Drag & drop | Hard |
| 90 | Coercion flow: null >= 0 | Type Coercion | Drag & drop | Hard |