unistore

A tiny ~650b centralized state container with component bindings for Preact.

• Small footprint compliments Preact nicely
• Familiar names and ideas from Redux-like libraries
• Useful data selectors to extract properties from state
• Portable actions can be moved into a common place and imported
• Functional actions are just reducers

Table of Contents

• Install
• Usage
• Examples
• API
• License

Install

This project uses node and npm. Go check them out if you don't have them locally installed.

npm install --save unistore

Then with a module bundler like webpack or rollup, use as you would anything else:

// using ES6 modules
import { createStore, Provider, connect } from 'unistore'

// using CommonJS modules
const unistore = require('unistore')

The UMD build is also available on unpkg:

<script src="//unpkg.com/unistore/dist/unistore.umd.js"></script>

You can find the library on window.unistore.

Usage

import { Provider, createStore, connect } from 'unistore'

let store = createStore({ count: 0 })

// If actions is a function, it gets passed the store:
let actions = store => ({
  // Actions can just return a state update:
  increment(state) {
    return { count: state.count+1 }
  },

  // The above example as an Arrow Function:
  increment2: ({ count }) => ({ count: count+1 }),

  //Actions receive current state as first parameter and any other params next
  //check this function as <button onClick={incrementAndLog}>
  incrementAndLog: ({ count }, event) => {
    console.info(event)
    return { count: count+1 }
  },

  // Async actions can be pure async/promise functions:
  async getStuff(state) {
    let res = await fetch('/foo.json')
    return { stuff: await res.json() }
  },

  // ... or just actions that call store.setState() later:
  incrementAsync(state) {
    setTimeout( () => {
      store.setState({ count: state.count+1 })
    }, 100)
  }
})

const App = connect('count', actions)(
  ({ count, increment }) => (
    <div>
      <p>Count: {count}</p>
      <button onClick={increment}>Increment</button>
    </div>
  )
)

export default () => (
  <Provider store={store}>
    <App />
  </Provider>
)

Examples

README Example on CodeSandbox

API

createStore

Creates a new store, which is a tiny evented state container.

Parameters

• state Object Optional initial state (optional, default {})

Examples

let store = createStore();
   store.subscribe( state => console.log(state) );
   store.setState({ a: 'b' });   // logs { a: 'b' }
   store.setState({ c: 'd' });   // logs { a: 'b', c: 'd' }

Returns store

store

An observable state container, returned from createStore

setState

Apply a partial state object to the current state, invoking registered listeners.

Parameters

• update Object An object with properties to be merged into state
• overwrite Boolean If true, update will replace state instead of being merged into it (optional, default false)

subscribe

Register a listener function to be called whenever state is changed, and returns the unsubscribe for that listener.

Parameters

• listener Function A function to call when state changes. Gets passed the new state.

Returns Function unsubscribe()

unsubscribe

Remove a previously-registered listener function.

Parameters

• listener Function The callback previously passed to subscribe() that should be removed.

getState

Retrieve the current state object.

Returns Object state

connect

Wire a component up to the store. Passes state as props, re-renders on change.

Parameters

• mapStateToProps (Function | Array | String) A function mapping of store state to prop values, or an array/CSV of properties to map.
• actions (Function | Object)? Action functions (pure state mappings), or a factory returning them. Every action function gets current state as the first parameter and any other params next

Examples

const Foo = connect('foo,bar')( ({ foo, bar }) => <div /> )

const actions = { someAction }
   const Foo = connect('foo,bar', actions)( ({ foo, bar, someAction }) => <div /> )

Returns Component ConnectedComponent

Provider

Extends Component

Provider exposes a store (passed as props.store) into context.

Generally, an entire application is wrapped in a single <Provider> at the root.

Parameters

• props Object
  • props.store Store A {Store} instance to expose via context.

Reporting Issues

Found a problem? Want a new feature? First of all see if your issue or idea has already been reported. If don't, just open a new clear and descriptive issue.

License

MIT License © Jason Miller