复制
1const first = () => (new Promise((resolve, reject) => {
2    console.log(3);
3    let p = new Promise((resolve, reject) => {
4        console.log(7);
5        setTimeout(() => {
6            console.log(5);
7            resolve(6);
8            console.log(p)
9        }, 0)
10        resolve(1);
11    });
12    resolve(2);
13    p.then((arg) => {
14        console.log(arg);
15    });
16}));
17first().then((arg) => {
18    console.log(arg);
19});
20console.log(4);
21