Asynchronous map function that await's returns Promise instead of value

Question

I have this code

async function addFiles(dir,tree) {
  return (await readDir(dir))
    .map(async (name) => {await readDir(dir); return name;})
}

but unfortunately, it just returns a bunch of promises, because there the async function in map is not waited upon. I'm wondering if there is any way to await the mapped function in the above code.

I believe `return Promise.all((await readDir(dir)).map(...));` should work. Not sure if it has to be `await Promise.all(...)`. — Felix Kling, May 02 '16 at 22:30

score 41 · Accepted Answer · answered May 02 '16 at 23:32

41

try

async function addFiles(dir,tree) {
  const files = await readDir(dir)
  await Promise.all(files.map(async (name) => {await readDir(dir); return name;})
}

answered May 02 '16 at 23:32

Sitian Liu

1,156
10
14

score 2 · Answer 2 · answered Mar 09 '17 at 06:46

2

If you're using bluebird you can use this cleaner, shorter syntax with Promise.map

async function addFiles(dir, tree) {
  const files = await readDir(dir);
  return Promise.map(files, async (name) => { await readDir(dir); return name; });
}

answered Mar 09 '17 at 06:46

gafi

12,113
2
30
32

Asynchronous map function that await's returns Promise instead of value

2 Answers2

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