modify array after promise.all in foreach loop

Question

I have an array like this

 let result =  [{id:1,name:'test',dealValue:'ds',dealType:2},{id:2,name:'test1',dealValue:'ds',dealType:4}];

I am looping the above array to call another function which is also a promise after each iteration I need to add the value as a new item in the current array.

let temp = [];

result.forEach((element, index) => {
    //build the promise    
    temp.push(getAmount(element.dealValue, element.dealType));
  });
  //execute array of promise
  let r = await Promise.all(temp);
  //add new key value pair
  result.forEach((element, index) => {
    element.IDGfee = r[index];
  });

This works fine, however, I am running two foreach loops to achieve my desired result ,is there any better way to do this??

Array items are a little bit different than the original apart from that everything is used — shamon shamsudeen
– shamon shamsudeen, Commented Feb 19, 2019 at 9:04

CertainPerformance · Accepted Answer · 2019-02-19 09:09:23Z

1

You could use .map instead, and assign back to element inside a .then chained onto the getAmount call:

await Promise.all(
  result.map((element) => (
    getAmount(element.dealValue, element.dealType)
      .then((result) => {
         element.IDGfee = result;
      })
  ))
);

(Though, as comment notes, this will not wait for every response to come back before assigning to each element - your current code will throw before assigning if any request throws an error, whereas this may well throw after some properties have been assigned to.)

edited Feb 19, 2019 at 9:09

answered Feb 19, 2019 at 9:05

CertainPerformance

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1 Comment

Shubham Khatri Over a year ago

The behaviour in your code and the OP code might be different depending upon what the OP wants to do incase any one call fails.

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