Discussion on: What's the order of execution?

That's going to be 3, 2, 1. Why:
Start execution. Put setTimeout's callback into the task queue. Since a promise is already resolved, put then's callback into the microtask queue. Execute console.log('3');. Then we execute the microtask(then's callback) and its console.log(2); because microtasks are executed before regular tasks whenever the call stack empties. Then the task(setTimeout's callback) executed and console.log(1); in it.