When JavaScript takes its coffee break?
summary
Explains exact mechanics: call stack → Web API → queue with demos that show a zero-delay setTimeout taking ≈4ms and promises (microtasks) running before timers. Shows three live animations so microtasks freeze the main thread while requestAnimationFrame runs at screen refresh (requestAnimationFrame 60Hz), and setTimeout fires about 166× per second in the demo versus 60 for RAF (microtask vs task priority). Mentions QMicrotask API, Node process.nextTick and the new scheduler API, and using the performance tab to debug.
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chapters (14)
- 0:00JavaScript event loop intro
- 2:45Single-threaded JS basics
- 4:51Async tasks in event loop
- 8:45Render timing with event loop
- 10:07Microtask vs task priority
- 13:48Promise order in event loop
- 15:59Blocking main thread
- 17:23Task vs microtask queues
- 18:49Animation frame rate
- 19:53Demo: task types in animation
- 23:07Microtask function tips
- 24:35Event loop in frameworks
- 25:39Learning event loop
- 26:46JS spec and event loop
