How does Node.js handle asynchronous code internally?

Short answer: Explain the event loop phases. Node.js uses the event loop to handle async tasks without blocking. Main phases: Timers: Executes callbacks scheduled by setTimeout and setInterval. Pending callbacks: Executes I/O callbacks deferred to next iteration. Idle, prepare: Internal operations. Poll: Retrieves new I/O events; executes I/O callbacks. Check: Executes callbacks scheduled by setImmediate. Close callbacks: Handles…

Explain a bit more

closed connections. Tasks are processed in this order each loop iteration.

Real-world example (ShopNest)

ShopNest’s Node API handles many checkout requests concurrently because I/O (DB/HTTP) is non-blocking on the event loop.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.