When should I learn event loop phases?
After understanding the event loop concept. Phases (timers, pending, poll, check, close) explain where specific callbacks run. Understanding phases after the concept gives you context for why the order matters.
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More FAQs in A Roadmap to Mastering the Node.js Event Loop
In order: sync vs async, the event loop concept, event loop phases, microtasks vs macrotasks, setTimeout vs setImmediate vs nextTick, what blocks and what does not, and debugging and monitoring. Each step builds real understanding.
Sync vs async. Understand blocking vs non-blocking code and why Node.js uses async I/O. This is the foundation, because the event loop exists to make async I/O efficient on a single thread.
After understanding phases, microtasks, and blocking patterns. Debugging uses the CPU profiler, clinic.js, and event loop monitoring, which are only meaningful once you understand what the loop should be doing.
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