# Combine-Promises
[](https://www.npmjs.com/package/combine-promises)
Like Promise.all(array) but with an object.
```ts
import combinePromises from 'combine-promises';
const { user, company } = await combinePromises({
user: fetchUser(),
company: fetchCompany(),
});
```
Why:
- Insensitive to destructuring order typos
- Simpler async functional code
Features:
- TypeScript support
- Lightweight
- Feature complete
- Well-tested
- ESM / CJS
## TypeScript support
Good, native and strict TypeScript support:
- Return type correctly inferred from the input object
- All object values should be async
- Only accept objects (reject arrays, null, undefined...)
```ts
const result: { user: User; company: Company } = await combinePromises({
user: fetchUser(),
company: fetchCompany(),
});
```
## Insensitive to destructuring order
A common error with `Promise.all` is to have a typo in the destructuring order.
```js
// Bad: destructuring order reversed
const [company, user] = await Promise.all([fetchUser(), fetchCompany()]);
```
This code becomes particularly dangerous as size of the array promise grows over time.
With `combinePromises`, you are using explicit names instead of array indices, which makes the code more robust and not sensitive to destructuring order:
```js
// Good: we don't care about the order anymore
const { company, user } = await combinePromises({
user: fetchUser(),
company: fetchCompany(),
});
```
## Simpler async functional code
Suppose you have an object representing a friendship like `{user1: "userId-1", user2: "userId-2"}`, and you want to transform it to `{user1: User, user2: User}`.
You can easily do that:
```js
import combinePromises from 'combine-promises';
import { mapValues } from 'lodash';
const friendsIds = { user1: 'userId-1', user2: 'userId-2' };
const friends = await combinePromises(mapValues(friendsIds, fetchUserById));
```
Without this library: good luck to keep your code simple.
## Inspirations
Name inspired by [combineReducers](https://redux.js.org/api/combinereducers) from Redux.