storefy v1.0.2

Storefy

A tiny event-based Redux-like state manager for web.

• Small. 167 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.
• Immutable.

Browser Support

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Install

npm install storefy

Using unpkg CDN:

<script src="https://unpkg.com/storefy/dist/storefy.min.js"></script>

Examples

NodeJs:

const Storefy = Storefy

const store = Storefy(function (store) {
  store.on('@init', { count: 0 }) // Initial state
  store.on('increment', ({ count }) => ({ count: count + 1 }))
})

store.dispath('increment') // count = 1
store.dispath('increment') // count = 2

In a browser you can use the global Storefy function:

var store = Storefy(function (store) {
  store.on('@init', { count: 0 }) // Initial state
  store.on('increment', ({ count }) => ({ count: count + 1 }))
})

store.dispath('increment') // count = 1
store.dispath('increment') // count = 2

var store = Storefy({ count: 10 }) // Initial state
store.on('increment', ({ count }) => ({ count: count + 1 }))

store.dispath('increment') // count = 11
store.dispath('increment') // count = 12

Multiple modules: Initial state, reducers and business logic are packed in independent modules

// Users module
var users = function (store) {
  store.on('@init', { users: [] })
  store.on('users:add', function (state, data) {
    state.users.push(data)
  })
}
// Cart module
var cart = function (store) {
  store.on('@init', {
    cart: {
      products: [],
      budget: 0
    }
  })
  store.on('cart:add', function (state, data) {
    state.cart.products.push(data)
    state.cart.budget += data.cost
  })
}

var store = Storefy(users, cart, /* etc... */)

Vue:

Vue.prototype.$store = Storefy(function (store) {
  store.on('vue:init', function () { console.log('Vue has started!') })
})

var app = new Vue({
  mounted () {
    this.$store.dispath('vue:init')
  }
})

Typescript:

import { Storefy } from 'storefy'

// Initial state, reducers and business logic are packed in independent modules
let increment = (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 = Storefy(increment)

React:

import { useStorefy } from 'storefy/react' // or storefy/preact

export const Counter = () => {
  // Counter will be re-render only on `state.count` changes
  const { dispatch, count } = useStorefy('count')
  return <button onClick={() => dispatch('inc')}>{count}</button>
}

import { StoreContext } from 'storefy/react'

render(
  <StoreContext.Provider value={store}>
    <Counter />
  </StoreContext.Provider>,
  document.body
)

The Store

The store should be created with Storefy() function. It accepts mutiple arguments as modules.

Each module is just a function, which will accept a store and bind their event listeners.

// store/index.js
import { Storefy } from 'storefy'

import { projects } from './projects'
import { users } from './users'

export const store = Storefy(projects, users)

// 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 Storefy. The best moment to set an initial state.
• @dispatch will be fired on every new action (on store.dispatch() calls and @changed event). 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 event name and callback.

store.on('@dispatch', (state, [event, data]) => {
  console.log(`Storefy: ${ event } with `, data)
})

store.on() will return cleanup function. This function will remove the event listener.

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.

// users: [] will be added to state on initialization
store.on('@init', { users: [] })

It could be a function too:

// users: [] will be added to state on initialization
store.on('@init', () => {
  { users: [] }
})

Event listener accepts the current state as a first argument and optional event object as a second.

So event listeners can be a reducer as well. As in Redux’s reducers, you should change immutable.

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.

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, useStorefy hook will be the best option:

import { useStorefy } from 'storefy/react' // Use 'storefy/preact' for Preact

const Users = () => {
  const { dispatch, users, projects } = useStorefy('users', 'projects')
  const onAdd = useCallback(user => {
    dispatch('users/add', user)
  })
  return <div>
    {users.map(user => <User key={user.id} user={user} projects={projects} />)}
    <NewUser onAdd={onAdd} />
  </div>
}

For class components, you can use connectStorefy() decorator.

import { connectStorefy } from 'storefy/react' // Use 'storefy/preact' for Preact

class Users extends React.Component {
  onAdd = () => {
    this.props.dispatch('users/add', user)
  }
  render () {
    return <div>
      {this.props.users.map(user => <User key={user.id} user={user} />)}
      <NewUser onAdd={this.onAdd} />
    </div>
  }
}

export default connectStorefy('users', 'anotherStateKey', Users)

useStorefy hook and connectStorefy() accept the list of state keys to pass into props. It will re-render only if this keys will be changed.

DevTools

Storefy supports debugging with Redux DevTools Extension.

import { storefyDevtools } from 'storefy/devtools';

const store = Storefy([
  …
  process.env.NODE_ENV !== 'production' && storefyDevtools
])

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 built-in logger. It could be useful for simple cases or to investigate issue in error trackers.

import { storefyLogger } from 'storefy/devtools';

const store = Storefy([
  …
  process.env.NODE_ENV !== 'production' && storefyLogger
])

TypeScript

Storefy delivers TypeScript declaration which allows to declare type of state and optionally declare types of events and parameter.

If Storefy store has to be full type safe the event types declaration interface has to be delivered as second type to createStore function.

import { Storefy, StoreonModufy } from 'storefy'
import { useStorefy } from 'storefy/react' // or storefy/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: StoreonModufy<State, Events> = store => {
  store.on('@init', () => ({ counter: 0}))
  store.on('inc', state => ({ counter: state.counter + 1}))
  store.on('set', (state, event) => ({ counter: event}))
}

const store = Storefy<State, Events>([counterModule])

const Counter = () => {
  const { dispatch, count } = useStorefy<State, Events>('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, it is considering adding allowSyntheticDefaultImports: true to tsconfig.json.

Server-Side Rendering

In order to preload data for server-side rendering, Storefy provide customContext function to create your own useStorefy hooks that it will depends on your custom context.

// store.jsx
import { createContext, render } from 'react' // or preact

import { Storefy, StoreonModufy } from 'storefy'
import { customContext } from 'storefy/react' // or storefy/preact

const store = …

const CustomContext = createContext(store)

// useStorefy will automatically recognize your storefy store and event types
export const useStorefy = customContext(CustomContext)

render(
  <CustomContext.Provider value={store}>
    <Counter />
  </CustomContext.Provider>,
  document.body
)

// children.jsx
import { useStorefy } from '../store'

const Counter = () => {
  const { dispatch, count } = useStorefy('count')

  dispatch('set', 100)
  …
}

Testing

Tests for store can be written in this way:

it('creates users', () => {
  let addUserResolve
  jest.spyOn(api, 'addUser').mockImplementation(() => new Promise(resolve => {
    addUserResolve = resolve
  }))
  let store = Storefy([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 the 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.