javascript - 如何正确使用Promise.all？

Question

考虑以下代码:

var result1;
var result1Promise = getSomeValueAsync().then(x => result1 = x);

var result2;
var result2Promise = getSomeValueAsync().then(x => result2 = x);

await Promise.all([result1Promise, result2Promise]);

// Are result1 and result2 guaranteed to have been set at this point?

console.log(result1 + result2); // Will this always work? Or could result1 and/or result2 be undefined because then() has not been executed yet?

当我使用then()方法时，它能保证按顺序执行吗？例如。 Promise.all 解析后 then() 不会立即执行？

它在 Chrome 中似乎工作正常，但我真正想要的是保证它始终按照某些规范工作？

我宁愿不使用 Promise.all(...).then(some callback) 因为然后我又会再次使用回调...

Answer 1

可以直接使用Promise.all的返回值:

const p1 = getSomeValueAsync();
const p2 = getSomeValueAsync();

const [result1, result2] = await Promise.all([p1, p2]);

console.log(result1 + result2);