consistency using async await with map

Question

I have big chunk of array of object. I want to get something then assign it to a new property, I did this

async function t() {
  return bigChunkArr.map(async o => ({
    ...o,
    address: await getAddress(o.lat, o.lng)
  }))
}
const result = await t() //expected to be array

The problem the result is still a promise, why?

`result` would be an array, no way `result` is a promise, since `array.map` always returns an array - also, the `const result = await t();` code must by in an `async` function - otherwise the code woudn't run **at all** — Jaromanda X, Jan 08 '20 at 10:27
also, no point in `async function t()` since you don't `await` in `t()` — Jaromanda X, Jan 08 '20 at 10:33
Is this an answer? https://stackoverflow.com/questions/40140149/use-async-await-with-array-map — Dmitry Reutov, Jan 08 '20 at 10:37
@NarendraChouhan - that would make the calls to getAddress run in series rather than potentially parallel — Jaromanda X, Jan 08 '20 at 10:38

score 1 · Answer 1 · answered Jan 08 '20 at 10:40

Map here will return an array of promises. We can use Promise.all to get the result of these promises when the return. In the code below, t will return a promise.

const t = () => {
    const promises = bigChunkArr.map(async (o) => {
        return {
            ...o,
            address: await getAddress(o.lat, o.lng)
        }
    });
    return Promise.all(promises);
}

consistency using async await with map

1 Answers1