Additionnal promise parameter javascript

Question

So i got this

for(var i =0;i<result.length;i++){
    User.find(result[i].user).then((err,user)=>{
        resultArray.push({name : result[i].name, userName : user.name});     
    }
}

but it doesn't work because the loops end before the promises resolves. So i wanted to know if i could give a copy of i to the User.find() callback? I don't know any way to keep the data synced between the result and user array, since i don't know in which order the promises are gonna be resolved.

Okay but, how can i know that every request has been completed? — Killian Allegrain, Jul 15 '17 at 01:30
@KillianAllegrain for these sorts of things you may want to consider using something like [async](https://github.com/caolan/async) or Promise.all — aug, Jul 15 '17 at 01:33
@KillianAllegrain it doesn't tell you when the promise returns, but with the `forEach` method, you're getting a copy of the array elements, and aren't relying on a constantly changing index (`i`) to access the result array — wbadart, Jul 15 '17 at 01:33
Just leave it open ;) Maybe someone else will stumble upon your question — lumio, Jul 15 '17 at 01:41

lumio · Answer 1 · 2017-07-15T01:40:31.553

0

Mentioned in the comments section, you want to resolve all users. You can use the Array method map to generate an Array of Promises to then pass to Promise.all, like so:

Promise.all(
  result.map( res => User.find( ... ) )
)
  .then( result => {
    // all resolved users are in result
  } );

edited Jul 15 '17 at 01:40

answered Jul 15 '17 at 01:33

lumio

7,428
4
40
56

So perfect ! Love you – Killian Allegrain Jul 15 '17 at 01:37
You are welcome. Feel free to accept my answer :) – lumio Jul 15 '17 at 01:41

Additionnal promise parameter javascript

1 Answers1