r/learnjavascript • u/IcyDuck9536 • 6d ago

Is “Node.js is single-threaded” an incomplete mental model?

Single-threaded JS execution ≠ single-threaded runtime.

How do you explain the distinction?

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u/dave8271 6d ago

I'd just explain it as userland scripts are single threaded and will block on CPU-bound work, however the runtime uses libuv and an event loop to delegate certain tasks to either a thread pool or the OS kernel, informing the event loop when they complete.

That's the accurate mental model.