在异步函数中使用 setTimeout [重复]

Question

我有一个异步函数，它等待 axios 调用完成后再继续。问题是我需要将 axios 调用超时设置为半秒，这样我就不会达到 shopify API 调用限制。

async function processMatchingSchools(customer_metafield_url) {
  for (const item of customer_metafield_url) {
    await axios.get(item).then((res) => {
      for (key in res.data.metafields) {
        if (res.data.metafields[key].value === schoolName) {
          id_for_each_student.push(shopifyAdmin + "/customers/" + res.data.metafields[key].owner_id + "/metafields.json")
        }
      }
    })
  }
  console.log("Customer metafields to search", id_for_each_student)
  processOwnerIds(id_for_each_student)
}

当我尝试放置 setTimeout 时，它会调用 setTimeout 并在完成 axios 调用之前继续前进。

async function processMatchingSchools(customer_metafield_url) {
  for (const item of customer_metafield_url) {
    await setTimeout(function(item) {
      axios.get(item).then((res) => {
        for (key in res.data.metafields) {
          if (res.data.metafields[key].value === schoolName) {
            id_for_each_student.push(shopifyAdmin + "/customers/" + res.data.metafields[key].owner_id + "/metafields.json")
          }
        }
      })
    }, 500)
  }
  console.log("Customer metafields to search", id_for_each_student)
  processOwnerIds(id_for_each_student)
}

有什么帮助吗？

Answer 1

await

仅适用于承诺。 你需要将

setTimeout

包裹在一个承诺中：

const waitFor = delay => new Promise(resolve => setTimeout(resolve, delay));

await waitFor(500);

Answer 2

setTimeout()

不会返回

Promise

，但您可以将其包装在这样的一个中。我还稍微清理了你其余的代码。

async function processMatchingSchools(customer_metafield_url) {
  for (const item of customer_metafield_url) {
    await new Promise(resolve => {
      setTimeout(resolve, 500)
    })

    const { data: { metafields } } = await axios.get(item)

    for (const { value, owner_id } of Object.values(metafields)) {
      if (value === schoolName) {
        id_for_each_student.push(`${shopifyAdmin}/customers/${owner_id}/metafields.json`)
      }
    }
  }

  console.log("Customer metafields to search", id_for_each_student)

  processOwnerIds(id_for_each_student)
}

Answer 3

setTimeout 不返回承诺，因此无法

await

ed。

您可以创建自己的基于承诺的

setTimeout

并使用它。

const setTimeoutPromise = timeout => new Promise(resolve => {        
  setTimeout(resolve, timeout);
});

await setTimeoutPromise(500);

Answer 4

创建一个

sleep

函数，返回您可以使用的 Promise，如下所示：

const sleep = (milliseconds=500) => new Promise(resolve => setTimeout(resolve, milliseconds))

并在异步函数中使用它：

(async () => {
  console.log("function invoked...")
  await sleep(500)
  console.log("I got here about 500 milliseconds later")
})()

Answer 5

您需要创建新的承诺，例如这样

function delay(ms){
 return new Promise(resolve => setTimeout(resolve, ms))
}

然后在调用 API 之前在代码中使用它

...
await delay(500)
await axios.get(item).then((res) => {
...

Answer 6

我创建了

setTimeout2

函数，其工作原理与承诺相同：

const setTimeout2 = (callback, ms) => {
  return new Promise(resolve => setTimeout(() => {
    callback();
    resolve();
  }, ms));
} 

所以，总共（注意 setTimeout2 的变化）：

async function processMatchingSchools(customer_metafield_url) {
  for (const item of customer_metafield_url) {
    await setTimeout2(function(item) {
      axios.get(item).then((res) => {
        for (key in res.data.metafields) {
          if (res.data.metafields[key].value === schoolName) {
            id_for_each_student.push(shopifyAdmin + "/customers/" + res.data.metafields[key].owner_id + "/metafields.json")
          }
        }
      })
    }, 500)
  }
  console.log("Customer metafields to search", id_for_each_student)
  processOwnerIds(id_for_each_student)
}