In what order will the numbers be output in code with Promise, setTimeout, and synchronous code (Event Loop)?

In JavaScript, the order of execution of code with Promise, setTimeout, and synchronous code is determined by the Event Loop and the queues of microtasks (microtasks) and macrotasks (macrotasks).

Let's consider an example:

console.log('1');

setTimeout(() => {
  console.log('2');
}, 0);

Promise.resolve().then(() => {
  console.log('3');
});

console.log('4');

Explanation:

• First, all synchronous code is executed, so '1' and '4' are logged.
• Then, microtasks (Promise) are executed, logging '3'.
• After that, macrotasks (setTimeout) are executed, logging '2'.

The final order of output is: '1', '4', '3', '2'.

Thus, synchronous code runs first, then microtasks (Promise), then macrotasks (setTimeout). This is a key point in understanding the Event Loop in JavaScript.