Using a setTimeout in a async function

Question

I have a async function that waits for an axios call to complete before proceeding. The problem is that I need to put a timeout on the axios call to half a second so that I don't hit the shopify API call limit.

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)
}

when I try putting a setTimeout, it calls the setTimeout and moves on before completing the axios calls.

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)
}

Any help?

Answer 1

await only works on promises. You need to wrap setTimeout in a promise:

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

await waitFor(500);

Answer 2

setTimeout() doesn't return a Promise , but you can wrap it in one like this. I also cleaned up the rest of your code a little.

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

    await axios.get(item).then((res) => {
      Object.values(res.data.metafields).filter(
        ({ value }) => value === schoolName
      ).forEach(({ owner_id }) => {
        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

Create a sleep function that returns a promise that you can use, like so:

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

And to use it in an async function:

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

Answer 4

setTimeout does not return a promise so cannot be await ed.

You could create your own promise-based setTimeout and use that.

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

await setTimeoutPromise(500);

Answer 5

You need to to create new promise for example like that

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

And then use it in your code before calling API

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