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JavaScriptIntermediate#async#promises
JavaScriptAdvanced#event-loop#async
What are microtasks and macrotasks?
Microtasks are promise reactions, queueMicrotask and MutationObserver callbacks; the queue is fully drained after each task. Macrotasks include setTimeout, setInterval, I/O and UI events, and only one runs per loop turn.
Example
setTimeout(() => console.log('macro'));
Promise.resolve().then(() => console.log('micro'));
// micro then macro