Create an object or associative array with elements of an existing array and the result of a callout for each element

Promise.all returns an array of results (one item per each promise).

Having this temporary structure it is possible to build the needed object.

const arrayOfMembers = Promise.all(ids.map(async id => { 
  // ...
  return { id, value: await callout(id) } // short syntax for { id: id, value: ... } (see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Object_initializer)
}));
// arrayOfMembers = [
//  { id: 211405, value: { name: 'name1', email: '[email protected]' } },
// ...
// ]

In pure JS it can be done with for loop or .forEach() call to iterate:

const res = {};
arrayOfMembers.forEach(el => {
  const { id, value } = el;
  res[el] = value;
});

or by using a single reduce() call

const res = arrayOfMembers.reduce((accumulator, el) => {
   const { id, value } = el;
   return { ...accumulator, [id]: value };
}, {});

in both cases res will be:

// res = {
//   '211405': { name: 'name1', email: '[email protected]' },
// ...
// }

P.S.

There is a handy library called lodash. It has tons of small methods for data manipulation.

For example, _.fromPairs() can build an object from [[key1, value1], [key2, value2]] pairs.

As you mentioned you have lodash, so I think the following should work:

const arrayOfKeyValuePairs = Promise.all(ids.map(async id => { 
  // ...
  return [ id, await callout(id) ] // array here so it matches what fromPairs needs
}));
const res = _.fromPairs(arrayOfKeyValuePairs);