BuildBot

Node Essentials

The event loop & async I/O

Lesson 2 of 5

Node stays on one thread by never waiting — it queues work and comes back to it.

What you'll learn

  • Understand why blocking is the enemy in a single-threaded runtime
  • Order synchronous code, microtasks, and timers correctly
  • See that promises run before timers within a tick
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Not sure yet? Try the free lesson first: Modules: ESM vs CommonJS