axios.get().then() for 循环

Question

我将如何在 for 循环中运行 Axios，每个循环都有相应的.then()函数。然后在 for 循环结束后，运行另一个函数。

例子：

const array = ['asdf', 'foo', 'bar'];
let users = [];
for (i = 0; i < array.length; i++) {
  axios.get('/user/' + array[i].id).then(response => {
    // do something with response
    users.push(response);
  });
}

console.log(users);

Answer 1

const array = [{ id: 'asdf'}, { id: 'foo' }, { id: 'bar' }]; // changed the input array a bit so that the `array[i].id` would actually work - obviously the asker's true array is more than some contrived strings
let users = [];
let promises = [];
for (i = 0; i < array.length; i++) {
  promises.push(
    axios.get('/user/' + array[i].id).then(response => {
      // do something with response
      users.push(response);
    })
  )
}

Promise.all(promises).then(() => console.log(users));

.then()Promise 本身的方法返回一个 Promise；所以你可以收集这些并用Promise.all().

请注意，即使您在一个async函数中执行此操作，您也不希望await在 for 循环内，因为每个请求将在它开始之前等待前一个完成，并且大概您想运行这些请求在平行下。

根据您的用例，简洁的 async / await 函数可能如下所示：

async function getMultiple(...objectsToGet) {
  let users = [];
  await Promise.all(objectsToGet.map(obj =>
    axios.get('/user/' + obj.id).then(response => {
      // do something with response
      users.push(response);
    })
  ));
  return users;
}

// some other async context
console.log(await getMultiple({ id: 'asdf'}, { id: 'foo' }, { id: 'bar' }));

Answer 2

如果您使用的是受支持的较新版本的 javascript async/await，您可以执行以下操作：

const array = ['asdf', 'foo', 'bar'];
let users = [];
for (const id in array) {
  const response = await axios('/user/' + id);
  users.push(response);
}

console.log(users);