microstate

Co-located, functional state management for React. seState syntatic sugar. 1.3kb

Usage

Wrap your application with the Provider.

import { Provider } from 'microstate'

const App = props => (
  <Provider>
    <h1>My App</h1>
  </Provider>
)

render(<App/>, root)

Connect your component to the provider state using connect. The function signature for connect looks like this:

connect(mapStateToProps[, mapDispatchToProps, initialState])(MyComp)

import { connect } from 'microstate'

const initialState = {
  count: 0
}

const mapStateToProps = state => ({
  count: state.count
})

const mapDispatchToProps = dispatch => ({
  inc: () => dispatch(state => {
    count: state.count + 1
  })
})

const Component = ({ inc, count }) => (
  <div>
    <button onClick={inc}>Increment</button>
    <span>{count}</span>
  </div>
)

export default connect(
  mapStateToProps,
  mapDispatchToProps,
  initialState
)(Component)

Then render your component within the Provider context.

import { Provider } from 'microstate'
import Component from './Component.js'

const App = props => (
  <Provider>
    <Component/>
  </Provider>
)

render(<App/>, root)

Note: the state is availabe at a component level and below during first render. However, since an initial render is required to evaluate the connect function, state will only be availabe at the application level after that first render.

Subscribing to state

Subscribing to another component's state is easy. Let's pretend the below is a different component than the counter above.

// Output.js
export default connect(
  state => ({
    count: state.count,
    text: state.text
  },
  null,
  {
    text: 'The count is'
  }
)(({ count, text }) => (
  <div>{text + ' ' + count}</div>
))

Then add it to the rendered App from above.

import { Provider } from 'microstate'
import Component from './Component.js'
import Output from './Output.js'

export default props => (
  <Provider>
    <Component/>
    <Output/>
  </Provider>
)

render(<App/>, root)

Note on Usage

This library is functional and has been used in production. However, the co-located nature of it means that the parent scope (and any other component subscribing to state that is external to itself) does not have access to the individual component state until after the first render. This is because the function hasn't fired (components are just functions) and so the co-located state hasn't been evaluated. The answer to this is to define all your state up front, at the top level, which this library doesn't do.

For similar (and better) options, I'd recommend refunk by @jxnblk or react-organism by @RoyalIcing.

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MIT License