# Storeon

A tiny event-based Redux-like state manager for **React**, **Preact**, **[Angular]**, **[Vue]** and **[Svelte]**. * **Small.** 180 bytes (minified and gzipped). No dependencies. It uses [Size Limit] to control size. * **Fast.** It tracks what parts of state were changed and re-renders only components based on the changes. * **Hooks.** The same Redux reducers. * **Modular.** API created to move business logic away from React components. Read more about Storeon features in **[our article]**. ```js import { createStoreon } from 'storeon' // Initial state, reducers and business logic are packed in independent modules let count = store => { // Initial state store.on('@init', () => ({ count: 0 })) // Reducers returns only changed part of the state store.on('inc', ({ count }) => ({ count: count + 1 })) } export const store = createStoreon([count]) ``` ```js import { useStoreon } from 'storeon/react' // or storeon/preact export const Counter = () => { // Counter will be re-render only on `state.count` changes const { dispatch, count } = useStoreon('count') return } ``` ```js import { StoreContext } from 'storeon/react' render( , document.body ) ``` [our article]: https://evilmartians.com/chronicles/storeon-redux-in-173-bytes [Size Limit]: https://github.com/ai/size-limit [Angular]: https://github.com/storeon/angular [Svelte]: https://github.com/storeon/svelte [Vue]: https://github.com/storeon/vue

## Tools * [`@storeon/router`](https://github.com/storeon/router) tracks links and Back button click and allows you to open pages without reloading the whole page. * [`@storeon/localstorage`](https://github.com/storeon/localstorage) saves and restores state to `localStorage` or `sessionStorage`. * [`@storeon/crosstab`](https://github.com/storeon/crosstab) synchronizes events between browser tabs. * [`@storeon/undo`](https://github.com/storeon/undo) allows undoing or redoing the latest event. * [`@storeon/websocket`](https://github.com/storeon/websocket) to sync actions through WebSocket. Third-party tools: * [`majo44/storeon-async-router`](https://github.com/majo44/storeon-async-router) is router with data prefetch, modules lazy load, navigation cancellation, and routes modification on the fly. * [`mariosant/storeon-streams`](https://github.com/mariosant/storeon-streams) is side effects management library. * [`octav47/storeonize`](https://github.com/octav47/storeonize) is migrating tool from Redux to Storeon. ## Install ```sh npm install storeon ``` If you need to support IE, you need to [compile `node_modules`] with Babel and add [`Object.assign`] polyfill to your bundle. You should have this polyfill already if you are using React. ```js import assign from 'object-assign' Object.assign = assign ``` [compile `node_modules`]: https://developer.epages.com/blog/coding/how-to-transpile-node-modules-with-babel-and-webpack-in-a-monorepo/ [`Object.assign`]: https://www.npmjs.com/package/object-assign ## Store The store should be created with the `createStoreon()` function. It accepts a list of functions. Each function should accept a `store` as the only argument and bind their event listeners using `store.on()`. ```js // store/index.js import { createStoreon } from 'storeon' import { projects } from './projects' import { users } from './users' export const store = createStoreon([projects, users]) ``` ```js // store/projects.js export function projects (store) { store.on('@init', () => ({ projects: [] })) store.on('projects/add', ({ projects }, project) => { return { projects: projects.concat([project]) } }) } ``` The store has 3 methods: * `store.get()` will return current state. The state is always an object. * `store.on(event, callback)` will add an event listener. * `store.dispatch(event, data)` will emit an event with optional data. ## Events There are three built-in events: * `@init` will be fired in `createStoreon`. Bind to this event to set the initial state. * `@dispatch` will be fired on every new action (on `store.dispatch()` calls and `@changed` events). It receives an array with the event name and the event’s data. Can be useful for debugging. * `@changed` will be fired when any event changes the state. It receives object with state changes. To add an event listener, call `store.on()` with the event name and a callback function. ```js store.on('@dispatch', (state, [event, data]) => { console.log(`Storeon: ${ event } with `, data) }) ``` `store.on()` will return a cleanup function. Calling this function will remove the event listener. ```js const unbind = store.on('@changed', …) unbind() ``` You can dispatch any other events. Just do not start event names with `@`. If the event listener returns an object, this object will update the state. You do not need to return the whole state, return an object with changed keys. ```js // users: {} will be added to state on initialization store.on('@init', () => ({ users: { } })) ``` An event listener accepts the current state as the first argument, optional event object as the second and optional store object as the third. So event listeners can be reducers as well. As in Redux’s reducers, your should change immutable. ```js store.on('users/save', ({ users }, user) => { return { users: { ...users, [user.id]: user } } }) store.dispatch('users/save', { id: 1, name: 'Ivan' }) ``` You can dispatch other events in event listeners. It can be useful for async operations. ```js store.on('users/add', async (state, user) => { try { await api.addUser(user) store.dispatch('users/save', user) } catch (e) { store.dispatch('errors/server-error') } }) ``` ## Components For functional components, the `useStoreon` hook will be the best option: ```js import { useStoreon } from 'storeon/react' // Use 'storeon/preact' for Preact const Users = () => { const { dispatch, users, projects } = useStoreon('users', 'projects') const onAdd = useCallback(user => { dispatch('users/add', user) }) return

{users.map(user => )}

} ``` For class components, you can use the `connectStoreon()` decorator. ```js import { connectStoreon } from 'storeon/react' // Use 'storeon/preact' for Preact class Users extends React.Component { onAdd = () => { this.props.dispatch('users/add', user) } render () { return

{this.props.users.map(user => )}

} } export default connectStoreon('users', 'anotherStateKey', Users) ``` `useStoreon` hook and `connectStoreon()` accept the list of state keys to pass into `props`. It will re-render only if this keys will be changed. ## DevTools Storeon supports debugging with [Redux DevTools Extension]. ```js import { storeonDevtools } from 'storeon/devtools'; const store = createStoreon([ … process.env.NODE_ENV !== 'production' && storeonDevtools ]) ``` DevTools will also warn you about **typo in event name**. It will throw an error if you are dispatching event, but nobody subscribed to it. Or if you want to print events to `console` you can use the built-in logger. It could be useful for simple cases or to investigate issues in error trackers. ```js import { storeonLogger } from 'storeon/devtools'; const store = createStoreon([ … process.env.NODE_ENV !== 'production' && storeonLogger ]) ``` [Redux DevTools Extension]: https://github.com/zalmoxisus/redux-devtools-extension ## TypeScript Storeon delivers TypeScript declarations which allows to declare type of state and optionally declare types of events and parameter. If a Storeon store has to be fully type safe the event types declaration interface has to be delivered as second type to `createStore` function. ```typescript import { createStoreon, StoreonModule } from 'storeon' import { useStoreon } from 'storeon/react' // or storeon/preact // State structure interface State { counter: number } // Events declaration: map of event names to type of event data interface Events { // `inc` event which do not goes with any data 'inc': undefined // `set` event which goes with number as data 'set': number } const counterModule: StoreonModule = store => { store.on('@init', () => ({ counter: 0})) store.on('inc', state => ({ counter: state.counter + 1})) store.on('set', (state, event) => ({ counter: event})) } const store = createStoreon([counterModule]) const Counter = () => { const { dispatch, count } = useStoreon('count') // Correct call dispatch('set', 100) // Compilation error: `set` event do not expect string data dispatch('set', "100") … } // Correct calls: store.dispatch('set', 100) store.dispatch('inc') // Compilation errors: store.dispatch('inc', 100) // `inc` doesn’t have data store.dispatch('set', "100") // `set` event do not expect string data store.dispatch('dec') // Unknown event ``` In order to work properly for imports, consider adding `allowSyntheticDefaultImports: true` to `tsconfig.json`. ## Server-Side Rendering In order to preload data for server-side rendering, Storeon provides the `customContext` function to create your own `useStoreon` hooks that depend on your custom context. ```js // store.jsx import { createContext, render } from 'react' // or preact import { createStoreon, StoreonModule } from 'storeon' import { customContext } from 'storeon/react' // or storeon/preact const store = … const CustomContext = createContext(store) // useStoreon will automatically recognize your storeon store and event types export const useStoreon = customContext(CustomContext) render( , document.body ) ``` ```js // children.jsx import { useStoreon } from '../store' const Counter = () => { const { dispatch, count } = useStoreon('count') dispatch('set', 100) … } ``` ## Testing Tests for store can be written in this way: ```js it('creates users', () => { let addUserResolve jest.spyOn(api, 'addUser').mockImplementation(() => new Promise(resolve => { addUserResolve = resolve })) let store = createStoreon([usersModule]) store.dispatch('users/add', { name: 'User' }) expect(api.addUser).toHaveBeenCalledWith({ name: 'User' }) expect(store.get().users).toEqual([]) addUserResolve() expect(store.get().users).toEqual([{ name: 'User' }]) }) ``` We recommend to keep business logic away from components. In this case, UI kit (special page with all your components in all states) will be the best way to test components. For instance, with [UIBook] you can mock store and show notification on any `dispatch` call. [UIBook]: https://github.com/vrizo/uibook/

	Stars	Issues	Version	Updated	Created
@reduxjs/toolkit	10,435	315	2.2.4	8 days ago	5 years ago
react-redux	23,256	27	9.1.2	15 days ago	9 years ago
recoil	19,457	320	0.7.7	a year ago	4 years ago
storeon	1,967	13	3.1.5	2 years ago	5 years ago
zustand			4.5.2	3 months ago	5 years ago

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