# react-states

> Explicit states for predictable user experiences

## Install

```sh
npm install react-states
```

## Introduction to react-states

[![react-states](https://img.youtube.com/vi/4M--Kp41CjI/0.jpg)](https://www.youtube.com/watch?v=4M--Kp41CjI)

## Examples

- [Resizer in the Devtools](./src/devtools//Resizer.tsx)
- [ExcalidrawFirebase](https://github.com/codesandbox/excalidraw-firebase/tree/main/src)
- [FamilyScrum](https://github.com/christianalfoni/family-scrum-v2/tree/main/src)

## Documentation

- [API](./docs/api.md)
- [Patterns](./docs/patterns.md)

## Values

- "It is just a reducer"
- Simple utilities
- Enhanced type safety
- Reducer does not express side effects

## Learn by example

Instead of expressing your state implicitly:

```ts
type State = {
  isLoading: boolean;
  error: string | null;
  data: string[];
};
```

You can do so explicitly:

```ts
type State =
  | {
      state: 'NOT_LOADED';
    }
  | {
      state: 'LOADING';
    }
  | {
      state: 'LOADED';
      data: string[];
    }
  | {
      state: 'ERROR';
      error: string;
    };
```

With explicit states you can guard what actions are valid in what states using `transition`:

```ts
import { transition } from 'react-states';

const reducer = (prevState: State, action: Action) =>
  transition(prevState, action, {
    NOT_LOADED: {
      FETCH: () => ({
        state: 'LOADING',
      }),
    },
    LOADING: {
      FETCH_SUCCESS: (_, { data }) => ({
        state: 'LOADED',
        data,
      }),
      FETCH_ERROR: (_, { error }) => ({
        state: 'ERROR',
        error,
      }),
    },
    LOADED: {},
    ERROR: {},
  });
```

With additional utilities like `createStates`, `createActions` and `match` you will increase safety and reduce boilerplate in your code.