Javascript，Promises和setTimeout

Question

我一直在玩Promises，但是在理解以下代码发生的事情时遇到了麻烦：

const promise = new Promise((resolve, reject) => {
  console.log('Promise started - Async code started')
  setTimeout(() => {
    resolve('Success')
  }, 10)
})

setTimeout(() => {
  console.log('Promise log inside first setTimeout')
}, 0)

promise.then(res => {
  console.log('Promise log after fulfilled')
})

console.log('Promise made - Sync code terminated')

setTimeout(() => {
  console.log('Promise log inside second setTimeout')
}, 0)

输出为：

Promise started - Async code started 
Promise made - Sync code terminated 
Promise log inside first setTimeout 
Promise log inside second setTimeout 
Promise log after fulfilled

符合预期。

但是让我们检查以下代码的输出：

const promise = new Promise((resolve, reject) => {
  console.log('Promise started - Async code started')
  setTimeout(() => {
    resolve('Success')
  }, 1)
})

setTimeout(() => {
  console.log('Promise log inside first setTimeout')
}, 0)

promise.then(res => {
  console.log('Promise log after fulfilled')
})

console.log('Promise made - Sync code terminated')
setTimeout(() => {
  console.log('Promise log inside second setTimeout')
}, 0)

将待解决的promise setTimeout计时器值从10ms更改为1ms

输出为：

Promise started - Async code started 
Promise made - Sync code terminated 
Promise log after fulfilled 
Promise log inside first setTimeout 
Promise log inside second setTimeout 

对此有任何解释吗？

Answer 1

我将使用以下示例进行说明：

Answer 2

来自Concurrency model and the event loop