| # | title | topic | type | difficulty |
|---|---|---|---|---|
| 91 | form.submit() skips the party | DOM Events | Multiple choice | Medium |
| 92 | Drag the propagation into order | DOM Events | Drag & drop | Medium |
| 93 | Event machine: which phase fires it? | DOM Events | Runtime machine | Medium |
| 94 | Mock, stub, or spy? | Testing Lifecycle | Multiple choice | Medium |
| 95 |
| The order-dependent test suite |
| Testing Lifecycle |
| Multiple choice |
| Medium |
| 96 | The test that fails on Tuesdays | Testing Lifecycle | Multiple choice | Medium |
| 97 | Test-double machine: which double does the job? | Testing Lifecycle | Runtime machine | Medium |
| 98 | Build makeSpy | Testing Lifecycle | Coding | Medium |
| 99 | Land three lines in three different queues | Async & Promises | Coding | Medium |
| 100 | Same results, a third of the wall clock | Async & Promises | Coding | Medium |
| 101 | Retry with a delay between attempts | Async & Promises | Coding | Medium |
| 102 | A timeout wrapper that races | Async & Promises | Coding | Medium |
| 103 | Promisify an error-first callback API | Async & Promises | Coding | Medium |
| 104 | allSettled: report everything, fail at nothing | Async & Promises | Coding | Medium |
| 105 | forEach does not wait, and it will not tell you | Async & Promises | Coding | Medium |
| 106 | Debounce: only the last one survives | Async & Promises | Coding | Medium |
| 107 | Throttle: one call per window, no queue | Async & Promises | Coding | Medium |
| 108 | Poll until it is ready, then stop | Async & Promises | Coding | Medium |
| 109 | The this machine: four call sites, four rules | this Binding | Runtime machine | Medium |
| 110 | The this machine: the binding falls off | this Binding | Runtime machine | Medium |
| 111 | The frame machine: where a rAF callback waits | Rendering & Frames | Runtime machine | Medium |
| 112 | The module machine: your first line is not first | Modules | Runtime machine | Medium |
| 113 | The pointer that walks the wrong way | Sorting Algorithms | gap | Medium |
| 114 | Two pointers, and the moment they meet | Algorithms & Recursion | gap | Medium |
| 115 | The smallest one, from where? | Sorting Algorithms | gap | Medium |
| 116 | Shrink until everyone agrees | Algorithms & Recursion | gap | Medium |
| 117 | Ten came before two | Sorting Algorithms | Multiple choice | Medium |
| 118 | Four walls, closing in | Algorithms & Recursion | gap | Medium |
| 119 | Which box does this cell belong to? | Algorithms & Recursion | gap | Medium |
| 120 | The same sort, without writing a sort | Sorting Algorithms | Coding | Medium |