Promise You'll Know It? The async JavaScript Quiz
summary
Live QR-based realtime quiz implemented over websockets runs for ~10–12 minutes with ~200 participants and eight multiple‑choice code questions; the UI occasionally needs a manual reload but participation hits ~90%+. Concrete takeaways: type assertions erased at runtime (no runtime validation), fetch resolves with a Response where ok can be false (doesn’t throw), caret ranges allow only patch bumps, microtask vs task ordering produces A D B C, and Promise.all doesn’t cancel remaining operations. Printed 600 magnets as prizes and slides plus code (valibot/sot mentioned) are on the website.
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chapters (10)
- 0:00Introduction
- 1:01Speaker and prizes
- 2:06JavaScript trivia
- 3:11Type assertion runtime
- 4:58HTTP 429 with fetch
- 6:46Console log order
- 8:51NPM version changes
- 10:14Promise.all rejection
- 11:58Async forEach behavior
- 13:09Final quiz
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