The answer
Forgetting that microtasks (promise callbacks) run before macrotasks (setTimeout, I/O callbacks). If your code assumes the order is the order you wrote it, you get bugs. Understand the order: sync, nextTick, promises, then macrotasks.
Common Async Timing Mistakes in Node.js Code
What is a common async timing mistake in Node.js?
More FAQs in Common Async Timing Mistakes in Node.js Code
Because it runs on the next event loop tick, not immediately. Code after it may run first, and promise microtasks run before it. Assuming it is instant causes bugs when code relies on specific timing.
Because nextTick runs before promises, both before macrotasks. If you use nextTick expecting it to run after promises, you get bugs. It is Node.js-specific and runs first among microtasks.
When multiple async operations modify shared state and interleave in unexpected ways. Be careful with shared state across async operations, and use proper sequencing where order matters, or immutable patterns.
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