What is the output of console.log('1'); setTimeout(() => console.log('2'), 0); console.log('3') in JavaScript?
1, 3, 2. The timer callback goes to the macrotask queue and runs after the synchronous code finishes.
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More FAQs in setTimeout Interview Questions in JavaScript
Because promise callbacks go to the microtask queue, which the event loop drains completely before touching the macrotask queue where setTimeout callbacks live.
3, 3, 3. var is function-scoped; all callbacks share one i, which is 3 by the time they run. Use let to fix this (logs 0, 1, 2).
No. The callback never runs before the delay. It may run later (if the call stack is busy or microtasks are queued), but never earlier than the delay.
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