为什么async1()中 return那里, 加await和不加await的输出结果不一样吗??
```javascript
async function async1() {
return await Promise.resolve(1);
}
async1().then((res) => {
console.log(res);
})
new Promise((resolve) => {
resolve('2');
}).then((res) => {
console.log(res);
}).then(() => {
console.log(3);
})
```