Make result from an Array.map() add into one array

Question

I have an array of strings ['string1', 'string2'] and I want to transform each one of them into (example: blob:http://something-new) but i get a result of (2) [Promise, Promise]. How to get the resolved value?

here is the code

const results = id.map(async assetId => {
    const responseIds = await API.assets.getAssetFileById(assetId);
    let asset = responseIds.data.asset;
    const urlCreator = window.URL || window.webkitURL;
    const blobFile = await file_helper.dataUrlToBlob(asset.file);

    return asset.file = await urlCreator.createObjectURL(blobFile);
});

console.log(results) // (2) [Promise, Promise]

Expected output:

console.log(results) // (2) ['blob:http://something-new1', 'blob:http://something-new2']

[Promise.all](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/all) — zerkms, Dec 12 '18 at 21:14
You should put the promises in `Promise.all()` and once they all resolve then create the array. This is similar to the forEach issue. — Get Off My Lawn, Dec 12 '18 at 21:14
`return X = await Y;` can have some funky behavior. Try doing `let X = await Y; return X;` — Abion47, Dec 12 '18 at 21:14
@zerkms I'm not sure of the exact reason but it's happened to me before where doing it the first way wasn't working where the second way did. It's also encouraged to do it that way by many style guides anyway, so I don't argue. — Abion47, Dec 12 '18 at 21:16
You get `Promise` because an `async` function always returns a promise. — Felix Kling, Dec 13 '18 at 00:13

score 2 · Answer 1 · answered Dec 12 '18 at 21:15

2

Promise.all(results).then(function(urls) {
  console.log(urls);
});

You need to wait for all of the promises to resolve, then you can work with them.

answered Dec 12 '18 at 21:15

Jordan Soltman

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Make result from an Array.map() add into one array

1 Answers1