# combine-promises

> [![NPM](https://img.shields.io/npm/dm/combine-promises.svg)](https://www.npmjs.com/package/combine-promises) [![CI](https://github.com/slorber/combine-promises/actions/workflows/main.yml/badge.svg)](https://github.com/slorber/combine-promises/actions/work

Latest version **1.2.0** (published 2023-08-17) · MIT license · 0 weekly downloads

## Install

```sh
npm install combine-promises
pnpm add combine-promises
yarn add combine-promises
bun add combine-promises
```

## Health

**Score 30/100 (F)** — status: abandoned.

Positive: has types; esm support; no vulnerabilities; high quality score.

Warnings: low downloads.

Negative: abandoned; low maintenance score.

## Facts

| | |
|---|---|
| Version | 1.2.0 |
| Published | 2023-08-17 |
| First published | 2021-04-07 |
| Weekly downloads | 0 |
| License | MIT |
| TypeScript types | bundled |
| Module format | ESM + CommonJS |
| Node | >=10 |
| Dependencies | 0 |
| Unpacked size | 13.3 KB |
| Known vulnerabilities | 0 |
| Install scripts | no |
| GitHub stars | 206 |
| Author | slorber |
| Maintainers | slorber |

## Links

- npm: https://www.npmjs.com/package/combine-promises
- Repository: https://github.com/slorber/combine-promises
- npm.io page: https://npm.io/package/combine-promises

## Recent versions

- 1.2.0 (latest) — 2023-08-17
- 1.1.0 — 2021-04-07
- 1.0.0 — 2021-04-07

## README

# Combine-Promises

[![NPM](https://img.shields.io/npm/dm/combine-promises.svg)](https://www.npmjs.com/package/combine-promises)
[![CI](https://github.com/slorber/combine-promises/actions/workflows/main.yml/badge.svg)](https://github.com/slorber/combine-promises/actions/workflows/main.yml)
![Size min](https://img.shields.io/bundlephobia/min/combine-promises.svg)
![Size minzip](https://img.shields.io/bundlephobia/minzip/combine-promises.svg)

Like `Promise.all([])` but for objects.

```ts
import combinePromises from 'combine-promises';

const { user, company } = await combinePromises({
  user: fetchUser(),
  company: fetchCompany(),
});
```

Why:

- Insensitive to destructuring order
- Simpler async functional code

Features:

- TypeScript support
- Lightweight
- Feature complete
- Well-tested
- ESM / CJS

--- 

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---

## Install

```
npm install combine-promises
// OR
yarn add combine-promises
```

## 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 becomes more dangerous as size of the promises array grows.

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'; // can be replaced by vanilla ES if you prefer

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.

---
_Source: https://npm.io/package/combine-promises · Machine-readable twin of the npm.io package page. Health data is recomputed on every publish._