Event Loop & Microtasks

console.log('Start');
Promise.resolve().then(() => console.log('Promise'));
setTimeout(() => console.log('Timeout'), 0);
console.log('End');

Start, Promise, Timeout, End
Start, End, Promise, Timeout
The output order demonstrates the event loop and microtask queue priority: 1) Synchronous code executes first ('Start' and 'End'), 2) Microtasks (Promises) execute before the next macrotask, 3) setTimeout callback is a macrotask and executes last, 4) Even with 0ms delay, setTimeout is scheduled as a macrotask, 5) This ordering is consistent across modern browsers, 6) Understanding this order is crucial for managing async code execution.
Start, Timeout, Promise, End
Start, End, Timeout, Promise