Is the event loop part of the JavaScript engine (V8)?
No. The event loop is part of the host environment (browser or Node.js). V8 provides the call stack and heap. The host provides the event loop, Web APIs, and queues.
Verify This Answer
Cross-check this information using these trusted sources:
More FAQs in Common Event Loop Misconceptions in JavaScript
No. The JS engine has one call stack (one thread). Web APIs may run on separate browser threads, but only one JS statement runs at a time. The event loop moves callbacks to the single stack.
No. The callback goes to the macrotask queue. The event loop runs it only after the call stack is empty and all microtasks are done. It runs after all synchronous code, not immediately.
No. Promise callbacks are microtasks; setTimeout callbacks are macrotasks. Microtasks always run before macrotasks, regardless of when they were scheduled. This is why a promise runs before a timer with 0 delay.
Still have questions?
Browse all our FAQs or reach out to our support team