unistore
A tiny 350b centralized state container with component bindings for Preact & React.
- Small footprint complements Preact nicely (unistore + unistore/preact is ~650b)
- 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
- NEW: seamlessly run Unistore in a worker via Stockroom
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:
// The store:
import createStore from 'unistore'
// Preact integration
import { Provider, connect } from 'unistore/preact'
// React integration
import { Provider, connect } from 'unistore/react'
Alternatively, you can import the "full" build for each, which includes both createStore and the integration for your library of choice:
import { createStore, Provider, connect } from 'unistore/full/preact'
The UMD build is also available on unpkg:
<!-- just unistore(): -->
<script src="https://unpkg.com/unistore/dist/unistore.umd.js"></script>
<!-- for preact -->
<script src="https://unpkg.com/unistore/full/preact.umd.js"></script>
<!-- for react -->
<script src="https://unpkg.com/unistore/full/react.umd.js"></script>
You can find the library on window.unistore.
Usage
import createStore from 'unistore'
import { Provider, connect } from 'unistore/preact'
let store = createStore({ count: 0, stuff: [] })
let actions = {
// Actions can just return a state update:
increment(state) {
// The returned object will be merged into the current 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
// See the "Increment by 10"-button below
incrementBy: ({ count }, incrementAmount) => {
return { count: count+incrementAmount }
},
}
// If actions is a function, it gets passed the store:
let actionFunctions = store => ({
// Async actions can be pure async/promise functions:
async getStuff(state) {
const res = await fetch('/foo.json')
return { stuff: await res.json() }
},
// ... or just actions that call store.setState() later:
clearOutStuff(state) {
setTimeout(() => {
store.setState({ stuff: [] }) // clear 'stuff' after 1 second
}, 1000)
}
// Remember that the state passed to the action function could be stale after
// doing async work, so use getState() instead:
async incrementAfterStuff(state) {
const res = await fetch('foo.json')
const resJson = await res.json()
// the variable 'state' above could now be old,
// better get a new one from the store
const upToDateState = store.getState()
return {
stuff: resJson,
count: upToDateState.count + resJson.length,
}
}
})
// Connecting a react/preact component to get current state and to bind actions
const App1 = connect('count', actions)(
({ count, increment, incrementBy }) => (
<div>
<p>Count: {count}</p>
<button onClick={increment}>Increment</button>
<button onClick={() => incrementBy(10)}>Increment by 10</button>
</div>
)
)
// First argument to connect can also be a string, array or function while
// second argument can be an object or a function. Here we pass an array and
// a function.
const App2 = connect(['count', 'stuff'], actionFunctions)(
({ count, stuff, getStuff, clearOutStuff, incrementAfterStuff }) => (
<div>
<p>Count: {count}</p>
<p>Stuff:
<ul>{stuff.map(s => (
<li>{s.name}</li>
))}</ul>
</p>
<button onClick={getStuff}>Get some stuff!</button>
<button onClick={clearOutStuff}>Remove all stuff!</button>
<button onClick={incrementAfterStuff}>Get and count stuff!</button>
</div>
)
)
export const getApp1 = () => (
<Provider store={store}>
<App1 />
</Provider>
)
export const getApp2 = () => (
<Provider store={store}>
<App2 />
</Provider>
)
Debug
Make sure to have Redux devtools extension previously installed.
import createStore from 'unistore'
import devtools from 'unistore/devtools'
let initialState = { count: 0 };
let store = process.env.NODE_ENV === 'production' ? createStore(initialState) : devtools(createStore(initialState));
// ...
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
action
Create a bound copy of the given action function.
The bound returned function invokes action() and persists the result back to the store.
If the return value of action is a Promise, the resolved value will be used as state.
Parameters
action Function An action of the form action(state, ...args) -> stateUpdate
Returns Function boundAction()
setState
Apply a partial state object to the current state, invoking registered listeners.
Parameters
update Object An object with properties to be merged into stateoverwrite 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. Returns an unsubscribe() function.
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 not, just open a new clear and descriptive issue.
License
MIT License © Jason Miller
