promise-hash/README.md

Adds an RSVP-like Promise.hash() method for resolving groups of promises.

# promise-hash [![npm](https://img.shields.io/npm/dm/promise-hash.svg)](https://www.npmjs.com/package/promise-hash) [![Travis](https://img.shields.io/travis/mtimofiiv/promise-hash.svg?maxAge=2592000)](https://travis-ci.org/mtimofiiv/promise-hash)

In the current [Promises](https://www.promisejs.org/) implementation that Node.js uses, there exists the `Promise.all()` method, which resolves an array of promises. But what that implementation really misses is the way the [rsvp](https://github.com/tildeio/rsvp.js/) library allows you to pass an object to a promise and retain the data structure of that promise.

This library adds this functionality.

## Getting Started

```
npm install --save promise-hash
```

In your app, you can then do this:

```js
require('promise-hash');
```

Because it functions as a _polyfill_, all you need to do is include this in your code and the `Promise` object will be polyfilled to include the `#hash()` method.

If you prefer to not to polyfill the `Promise` object, you can use it directly:

```js
var hash = require('promise-hash/lib/promise-hash')

```

## Usage Example

```js
require('promise-hash');

function dummyPromise(value) {
  return new Promise((resolve, reject) => {
    setTimeout(resolve, 100, value);
  });
}

const promises = {
  promise1: dummyPromise('this is the first promise'),
  promise2: dummyPromise('this is the second promise'),
  promise3: dummyPromise('this is the third promise')
};

Promise.hash(promises).then(results => {
  console.log(results); // { promise1: 'this is the first promise', promise2: ... }
});
```

## Nodejs Garbage Collection

If you start getting `Promise.hash is not a function`, then the culprit is Nodejs's garbage collection. I'm looking into ways of solving this properly (feel free to send me a note if you know a good way!), but in the meantime, try putting the `require` into an active closure.