在Promise.all数组之后无法访问已解析的promise的值[重复]

Question

这个问题在这里已有答案：

• Promise.all in JavaScript: How to get resolve value for all promises? 2回答
• How to access the value of a promise? 9个答案
• How to fetch value from Promise object after promise has been resolved 1回答

在Promise.all之后无法访问已解决的承诺的值。正如您在下面的示例中看到的那样，res.prop打印未定义。我想我可以创建一个包装函数，将已解析的值推送到另一个responses数组，但这似乎不是一个干净的方法。

(async () => {
    const responses = []

    let counter = 10
    while (counter--) {
      responses.push(new Promise(resolve => resolve({prop: 10})))
    }

    await Promise.all(responses)

    for (const res of responses) {
        console.log(res) // -> prints Promise {prop: 10}
        console.log(res.prop) // -> prints undefined
    }
})()

Answer 1

你永远不会使用await Promise.all(responses)的返回值。您的承诺的返回值由Promises.all返回：

(async () => {
    const responses = []

    let counter = 10
    while (counter--) {
      responses.push(new Promise(resolve => resolve({prop: 10})))
    }

    const results = await Promise.all(responses)

    for (const res of results) {
        console.log(res) // -> prints Promise {prop: 10}
        console.log(res.prop) // -> prints undefined
    }
})()