为什么我不能用我的函数传递变量？ [复制]

Question

我在使用 firebase 的 react 本机应用程序中有此代码：

let bestTutors = [];

const getBestTutors = async () => {
    const snapshot = await getDoc(docRef);
    bestTutors = snapshot.data().list;
}

getBestTutors();

console.log(bestTutors);

但是当我运行它时，它只显示控制台日志“Array[]”，我尝试使用 .then() 和所有其他对我来说没有意义的东西，如果有需要使用它的话，idk没有等待或我如何将数据传递给变量:(？

Answer 1

看看我的cmets

您的代码 1

let bestTutors = [];

const getBestTutors = async () => {
    const snapshot = await getDoc(docRef);
    bestTutors = snapshot.data().list;
}

getBestTutors(); // Asynchronous function

console.log(bestTutors); // this is called before getBestTutors() returns the data. So console.log(bestTutors) return de default value: []

新代码

let bestTutors = [];

const getBestTutors = async () => {
    const snapshot = await getDoc(docRef);
    bestTutors = snapshot.data().list;
}

await getBestTutors(); // Wait until getBestTutors() has finished and then Next.

console.log(bestTutors);

Answer 2

使用等待调用函数。喜欢这个

await getBestTutors()