复制
1const promise = new Promise((resolve, reject) => {
2  setTimeout(() => {
3    console.log('timer')
4    resolve('success')
5  }, 1000)
6})
7const start = Date.now();
8promise.then(res => {
9  console.log(res, Date.now() - start)
10})
11promise.then(res => {
12  console.log(res, Date.now() - start)
13})
14