console.log(1) setTimeout(() => { console.log(2) }, 10) setTimeout(() => { Promise.resolve().then(() => console.log(3)) }, 0); setTimeout(() => { console.log(4) }, 0); new Promise((_, reject) => { console.log(5) reject(6) console.log(7) }).then(() => console.log(8)) .catch(() => console.log(9)) .then(() => console.log(10)) .catch(() => console.log(11)) .then(() => console.log(12)) .then(console.log) .finally(() => console.log(13)) console.log(14)

Let's analyze the order of output to the console step by step:

console.log(1)

setTimeout(() => {
    console.log(2)
}, 10)

setTimeout(() => {
    Promise.resolve().then(() => console.log(3))
}, 0);

setTimeout(() => {
    console.log(4)
}, 0);

new Promise((_, reject) => {
    console.log(5)
    reject(6)
    console.log(7)
}).then(() => console.log(8))
  .catch(() => console.log(9))
  .then(() => console.log(10))
  .catch(() => console.log(11))
  .then(() => console.log(12))
  .then(console.log)
  .finally(() => console.log(13))

console.log(14)

1. Synchronous code executes immediately:

   • console.log(1) → 1
   • In the promise constructor: console.log(5) → 5
   • console.log(7) → 7
   • console.log(14) → 14

2. The promise is rejected (reject(6)), so the .catch() chain is triggered.

3. Microtasks (Promise handlers) execute after the current stack:

   • .catch(() => console.log(9)) → 9
   • .then(() => console.log(10)) → 10
   • .catch() is skipped as there is no error
   • .then(() => console.log(12)) → 12
   • .then(console.log) — receives undefined (result of previous then), outputs undefined
   • .finally(() => console.log(13)) → 13

4. Macrotasks (setTimeout) execute after microtasks:

   • setTimeout(..., 0) with Promise.resolve().then(() => console.log(3)) — the setTimeout triggers first, inside which a microtask logs 3
   • setTimeout(..., 0) with console.log(4) — logs 4
   • setTimeout(..., 10) with console.log(2) — logs 2

Final output order:

1
5
7
14
9
10
12
undefined
13
3
4
2

Explanation:

• First, synchronous code runs.
• Then, promise handlers (microtasks).
• Next, setTimeout with 0 delay (macrotasks), which may contain microtasks.
• Finally, setTimeout with 10 ms delay.