# Introduction

## Installation

First, install the middleware.

```
npm i redux-promise-middleware -s
```

## Setup

Import the middleware and include it in `applyMiddleware` when creating the Redux store:

```javascript
import promise from 'redux-promise-middleware'

composeStoreWithMiddleware = applyMiddleware(
  promise,
)(createStore)
```

## Use

Dispatch a promise as the value of the `payload` property of the action.

```javascript
const foo = () => ({
  type: 'FOO',
  payload: new Promise()
});
```

A pending action is immediately dispatched.

```javascript
{
  type: 'FOO_PENDING'
}
```

Once the promise is settled, a second action will be dispatched. If the promise is resolved a fulfilled action is dispatched.

```javascript
{
  type: 'FOO_FULFILLED'
  payload: {
    ...
  }
}
```

On the other hand, if the promise is rejected, a rejected action is dispatched.

```javascript
{
  type: 'FOO_REJECTED'
  error: true,
  payload: {
    ...
  }
}
```

That's it!

## Further Reading

* [Catching Errors Thrown by Rejected Promises](https://pburtchaell.gitbook.io/redux-promise-middleware/guides/rejected-promises)
* [Use with Reducers](https://pburtchaell.gitbook.io/redux-promise-middleware/guides/reducers)
* [Optimistic Updates](https://pburtchaell.gitbook.io/redux-promise-middleware/guides/optimistic-updates)
* [Design Principles](https://pburtchaell.gitbook.io/redux-promise-middleware/getting-started/design-principles)

Copyright (c) 2017 Patrick Burtchaell. [Code licensed with the MIT License (MIT)](https://github.com/pburtchaell/redux-promise-middleware/tree/612043ca69fd1856bc52f308ae92bfd5e9b5c91c/LICENSE/README.md). [Documentation licensed with the CC BY-NC License](https://github.com/pburtchaell/redux-promise-middleware/tree/612043ca69fd1856bc52f308ae92bfd5e9b5c91c/docs/LICENSE/README.md).