typescript get values of Promise.allSettled

Question

I want to get values of Promise allSettled result in typescript code. In JavaScript this work well.

  Promise.allSettled([
      Promise.resolve(33),
      new Promise(resolve => setTimeout(() => resolve(1000), 0)),
      25000,
      Promise.reject(new Error('failed!'))
    ])
    .then(values => {
      let allValues = values.filter(c=>c.status === 'fulfilled').map(v=>v.value);
      console.log(allValues);
    });

But in typescript I can't find correct syntax. the item just have status and has no value property. I am using the latest version of typescript 3.9.7

Can you provide more information? What syntax are you using in Typescript? Are you receiving any errors? — Dom, Jul 18 '20 at 19:47
With the same syntax like JavaScript I get compile time error. I just want to do the same job in typescript. — Hamed Mahdizadeh, Jul 18 '20 at 19:49
@PoulKruijt ok. like javascript I can filter result based on status in typescript but how can I get the value property of the result? — Hamed Mahdizadeh, Jul 18 '20 at 19:59
try changing `es2019` to `es2020` in `lib` array and see if it resolves. — micronyks, Jul 18 '20 at 20:17
https://stackoverflow.com/questions/60276013/property-allsettled-does-not-exist-on-type-promiseconstructor-ts2339/60276174#60276174 — micronyks, Jul 18 '20 at 20:23
The Promise.allSettled result is of PromiseSetteledResult[] type. I don't now how can I manually overwrite it for having the value property! — Hamed Mahdizadeh, Jul 18 '20 at 20:45
@micronyks have read this "stackoverflow.com/questions/60276013/…" but I couldn't understand how can I use the approach this to fix this issue. — Hamed Mahdizadeh, Jul 18 '20 at 20:48
"*I get compile time error*" - **which** error are you getting, and on what statement? — Bergi, Jul 18 '20 at 21:26

Hamed Mahdizadeh · Accepted Answer · 2022-07-06T09:04:35.187

Ok I finally found the correct syntax for using Promise.allSettled in typescript:

Update: Thanks to @myol I updated the code without unnecessary map:

const dummyResolve1 =  Promise.resolve(1000);
const dummyResolve2 = new Promise(resolve => setTimeout(() => resolve(2000), 0));
const dummyError = Promise.reject(new Error('failed'));
const dummyPromises = [dummyResolve1, dummyResolve1, dummyError];

Promise.allSettled(dummyPromises)
  .then(results => {
    const allValues = (results.filter(c=>c.status === 'fulfilled') as PromiseFulfilledResult<any>[])
    .map(c=>c.value);

    console.log(allValues);

    const failedResults = 
    (results.filter(c=>c.status === 'rejected') as PromiseRejectedResult[])
    .map(c=>c.reason);
    
    console.log(failedResults);
});

Old code:

Promise.allSettled([
  Promise.resolve(1000),
  new Promise(resolve => setTimeout(() => resolve(2000), 0)),
  1500,
  Promise.reject(new Error('failed'))
])
.then(values => {
  let allValues = values.filter(c=>c.status === 'fulfilled').map(c=> <PromiseFulfilledResult<any>>c).map(c=>c.value);
  console.log(allValues);
  let failedResults =  values.filter(c=>c.status === 'rejected').map(c=> <PromiseRejectedResult>c).map(c=>c.reason);
  console.log(failedResults);
});

score 1 · Answer 2 · answered Jul 05 '22 at 13:58

I think you really want the following;

const fulfilledValues: any[] = (values as PromiseFulfilledResult<any>[])
  .filter(res => res.status === 'fulfilled')
  .map(res => res.value);
console.log(fulfilledValues);

const rejectedReasons: any[] = (values as PromiseRejectedResult[])
  .filter(res => res.status === 'rejected')
  .map(res => res.reason);
console.log(rejectedReasons);

No need for an extraneous JS .map call just to use type assertion in TS.

typescript get values of Promise.allSettled

2 Answers2