Changelog

effector 20.11.0

Add effect.inFlight store to effects. It show how many effect calls aren’t settled yet. Useful for rate limiting.

import {createEffect} from 'effector'

const fx = createEffect({
  handler: () => new Promise(rs => setTimeout(rs, 500)),
})

fx.inFlight.watch(amount => {
  console.log('in-flight requests:', amount)
})
// => 0

const req1 = fx()
// => 1

const req2 = fx()
// => 2

await Promise.all([req1, req2])

// => 1
// => 0

Try it

Documentation for effect.inFlight

Introduce withRegion: region-based memory management tool, which attach units (stores, events and effects) and watchers, created inside given callback to lifecycle of owner unit to be erased together with it.

import {createEvent, createDomain, withRegion} from 'effector'

const trigger = createEvent()

const domain = createDomain()

withRegion(domain, () => {
  trigger.watch(n => {
    console.log(n)
  })
})

trigger(0)
// => 0
clearNode(domain)
trigger(1)
// no reaction

Try it

Add support for Map<Store, any> to values property in fork.
Fix concurrent requests support in effect.pending: it will become false only after all pending effect calls becomes settled.

effector 20.10.0

Add launch({target: unit, params}) overload for launch - low level method for running computation in units (events, effects or stores). Mostly used by library developers for fine-grained control of computations.

effector 20.9.0, effector-react 20.6.0

Introduce effector/fork and effector-react/ssr: api for server side rendering and managing independent instances of application in general.

/**
 * app
 */
import {createDomain, forward, restore} from 'effector'
import {useStore, useList, Provider, useEvent} from 'effector-react/ssr'

export const app = createDomain()

const requestUsername = app.createEffect<{login: string}, string>()
const requestFriends = app.createEffect<string, string[]>()

const username = restore(requestUsername, 'guest')
const friends = restore(requestFriends, [])

forward({
  from: requestUserName.done.map(({result: username}) => username),
  to: requestFriends,
})

const Friends = () => (
  <ul>
    {useList(friends, friend => (
      <li>{name}</li>
    ))}
  </ul>
)

const Title = () => <header>Hello {useStore(username)}</header>

export const View = ({root}) => (
  <Provider value={root}>
    <Title />
    <Friends />
  </Provider>
)

/**
 * client
 */
import ReactDOM from 'react-dom'
import {fork} from 'effector/fork'
import {app, View} from './app'

// initialize app with values from server

const clientScope = fork(app, {
  values: window.__initialState__,
})

ReactDOM.hydrate(<View root={clientScope} />, document.getElementById('root'))

/**
 * server
 */
import express from 'express'
import {renderToString} from 'react-dom/server'
import {fork, serialize, allSettled} from 'effector/fork'

import {app, View} from './app'

export const server = express()

server.get('/user/:login', async (req, res) => {
  // clone application
  const scope = fork(app)
  // call requestUsername(req.params) in scope
  // and await all triggered effects
  await allSettled(requestUsername, {
    scope,
    params: req.params, // argument for requestUsername call
  })
  // save all stores in application to plain object
  const data = serialize(scope)
  // render dom content
  const content = renderToString(<View root={scope} />)
  res.send(`
    <body>
      ${content}
      <script>
        window.__initialState__ = ${JSON.stringify(data)};
      </script>
    </body>
  `)
})

This solution requires effector/babel-plugin in babel configuration:

{
  "plugins": ["effector/babel-plugin"]
}

Example application with express Serverless example

Add events created with createApi, stores created with restore and events created with .prepend to domain of given source units

import {createDomain, createApi, restore} from 'effector'
const domain = createDomain()
domain.onCreateStore(store => {
  console.log('store created')
})
domain.onCreateEvent(event => {
  console.log('event created')
})

const position = domain.createStore({x: 0})
// => store created
const {move} = createApi(position, {
  move: ({x}, payload) => ({x: x + payload}),
})
// => event created
const lastMove = restore(move, 0)
// => store created

Try it

effector 20.8.2

Improve combine batching in a few edge cases with nested combine calls

import {createEvent, createStore, combine} from 'effector'

const event = createEvent()
const store = createStore(0).on(event, s => s + 1)

const combined = combine([store, combine([store.map(d => d + 1)])])
combined.watch(e => fn(e))
// => [0, [1]]
event()
// => [1, [2]]

Try it

effector-react 20.5.2

Add ability to infer fn argument types without as const in useStoreMap. In effector-react 20.0.3 we introduced an improvement for useStoreMap types, which helps to infer types of fn arguments from keys. And now useStoreMap types improved even more: every item in second argument will have its own type even without as const, out from a box

Type tests

useStoreMap in docs

PR #274 (thanks @abliarsar)

import React from 'react'
import {createStore} from 'effector'
import {useStoreMap} from 'effector-react'

type User = {
  username: string
  email: string
  bio: string
}

const users = createStore<User[]>([
  {
    username: 'alice',
    email: 'alice@example.com',
    bio: '. . .',
  },
  {
    username: 'bob',
    email: 'bob@example.com',
    bio: '~/ - /~',
  },
  {
    username: 'carol',
    email: 'carol@example.com',
    bio: '- - -',
  },
])

export const UserProperty = ({id, field}: {id: number; field: keyof User}) => {
  const value = useStoreMap({
    store: users,
    keys: [id, field],
    fn: (users, [id, field]) => users[id][field] || null,
  })
  return <div>{value}</div>
}

effector 20.8.0

Allow to use objects and arrays with stores in sample source

import {createStore, createEvent, sample, combine} from 'effector'

const trigger = createEvent()
const objectTarget = createEvent()
const arrayTarget = createEvent()

const a = createStore('A')
const b = createStore('B')

sample({
  source: {a, b},
  clock: trigger,
  target: objectTarget,
})

sample({
  source: [a, b],
  clock: trigger,
  target: arrayTarget,
})

objectTarget.watch(obj => {
  console.log('sampled object', obj)
})
arrayTarget.watch(array => {
  console.log('sampled array', array)
})

trigger()
// sampled object {a: 'A', b: 'B'}
// sampled array ['A', 'B']

/* old way to do this: */

sample({
  source: combine({a, b}),
  clock: trigger,
  target: objectTarget,
})

sample({
  source: combine([a, b]),
  clock: trigger,
  target: arrayTarget,
})

Try it

effector-react 20.5.0

Pass props to Gate.open & Gate.close events

import {createGate} from 'effector-react'
const PageMeta = createGate()

PageMeta.open.watch(props => {
  console.log('page meta', props)
})

const App = () => (
  <>
    <PageMeta name="admin page" />
    <div>body</div>
  </>
)
ReactDOM.render(<App />, document.getElementById('root'))
// => page meta {name: 'admin page'}

Try it

effector 20.7.0

Add domain.createStore as alias for domain.store (proposal)
Add domain.createEvent as alias for domain.event
Add domain.createEffect as alias for domain.effect
Add domain.createDomain as alias for domain.domain

effector 20.6.2

Improve sample typings for typescript (PR #248, fix #247) (thanks @bloadvenro)

effector 20.6.1, effector-react 20.4.1, effector-vue 20.3.2

Add typescript typings for compat builds
Improve built-in source maps

effector 20.6.0

Add support for arrays to forward

import {createEvent, forward} from 'effector'

const firstSource = createEvent()
const secondSource = createEvent()
const firstTarget = createEvent()
const secondTarget = createEvent()

forward({
  from: [firstSource, secondSource],
  to: [firstTarget, secondTarget],
})

firstTarget.watch(e => console.log('first target', e))
secondTarget.watch(e => console.log('second target', e))

firstSource('A')
// => first target A
// => second target A
secondSource('B')
// => first target B
// => second target B

Try it

effector-vue 20.3.0

Add createComponent HOC for TypeScript usage. This HOC provides type-safe properties in vue components.

// component.vue
import {createStore, createApi} from 'effector'
import {createComponent} from 'effector-vue'

const $counter = createStore(0)
const {update} = createApi($counter, {
  update: (_, value: number) => value,
})

export default createComponent(
  {
    name: 'Counter',
    methods: {
      update,
      handleClick() {
        const value = this.$counter + 1 // this.$counter <- number ( typescript tips )
        this.update(value)
      },
    },
  },
  {$counter},
)

effector 20.5.0

Merge createStoreObject to combine to reduce api surface. Wherever createStoreObject was used, it can be replaced with combine

import {createStore, combine, createStoreObject} from 'effector'

const r = createStore(255)
const g = createStore(0)
const b = createStore(255)

const color = combine({r, g, b})
color.watch(console.log)
// => {r: 255, b: 0, b: 255}

const colorOld = createStoreObject({r, g, b})
colorOld.watch(console.log)
// => {r: 255, b: 0, b: 255}

Try it

Add ability to use arrays of stores with combine

import {createStore, combine} from 'effector'

const r = createStore(255)
const g = createStore(0)
const b = createStore(255)

const color = combine([r, g, b])
color.watch(console.log)
// => [255, 0, 255]

Try it

effector 20.4.4

Ensure that both effect.done and effect.fail are called before effect.finally watchers, thereby preventing side-effects from interrupting pure computations

effector 20.4.3

Throw expected error in case with sample({clock: undefined})

import {createStore, sample} from 'effector'
sample({
  source: createStore(null),
  clock: undefined,
})
// Throw "config.clock should be defined"

effector 20.4.1

Improve forward typings for typescript (PR #229, fix #174) (thanks @bloadvenro)
Add typescript typings for clearNode(domain), introduced in effector 20.2.0

effector-vue 20.2.1

Add typescript typings for object shape, introduced in effector-vue 20.2.0

const counter = createStore(0)

new Vue({
  effector: {
    counter, // would create `counter` in template
  },
})

effector 20.4.0

Introduce guard: conditional event routing Control one event with the help of another: when the condition and the data are in different places, then we can use guard with stores as a filters to trigger events when condition state is true, thereby modulate signals without mixing them

import {createStore, createEffect, createEvent, guard, sample} from 'effector'

const clickRequest = createEvent()
const fetchRequest = createEffect({
  handler: n => new Promise(rs => setTimeout(rs, 2500, n)),
})

const clicks = createStore(0).on(clickRequest, x => x + 1)
const requests = createStore(0).on(fetchRequest, x => x + 1)

const isIdle = fetchRequest.pending.map(pending => !pending)

/*
on clickRequest, take current clicks value,
and call fetchRequest with it
if isIdle value is true 
*/
guard({
  source: sample(clicks, clickRequest),
  filter: isIdle,
  target: fetchRequest,
})

See ui visualization

Also, guard can accept common function predicate as a filter, to drop events before forwarding them to target

import {createEffect, createEvent, guard} from 'effector'

const searchUser = createEffect()
const submitForm = createEvent()

guard({
  source: submitForm,
  filter: user => user.length > 0,
  target: searchUser,
})

submitForm('') // nothing happens
submitForm('alice') // ~> searchUser('alice')

Type inference Implementation tests

Introduce name property in sample parameters list

Each basic entity in Effector (event/effect/store/domain) may have a name. You now can name sampled entities in the same manner as basic ones.

import {createStore, sample} from 'effector'

const foo = createStore(null)

const sampled = sample({
  source: foo,
  name: 'sampled foo',
})

console.log(sampled.shortName) // 'sampled foo'

effector 20.3.2

Allow typescript to refine type with split method (PR)
Improve type inference of effects with optional arguments in Typescript (PR)
Ensure that effect handler is called only after effect update itself, thereby preventing side-effects from interrupting pure computations

import React from 'react'
import ReactDOM from 'react-dom'
import {createStore, createEvent, createEffect, sample} from 'effector'
import {useList} from 'effector-react'

const items$ = createStore([
  {id: 0, status: 'NEW'},
  {id: 1, status: 'NEW'},
])

const updateItem = createEvent()
const resetItems = createEvent()

const processItems = createEffect({
  async handler(items) {
    for (let {id} of items) {
      //event call inside effect
      //should be applied to items$
      //only after processItems itself
      updateItem({id, status: 'PROCESS'})
      await new Promise(r => setTimeout(r, 3000))
      updateItem({id, status: 'DONE'})
    }
  },
})

items$
  .on(updateItem, (items, {id, status}) =>
    items.map(item => (item.id === id ? {...item, status} : item)),
  )
  .on(processItems, items => items.map(({id}) => ({id, status: 'WAIT'})))
  .reset(resetItems)

const processClicked = createEvent()

sample({
  source: items$,
  clock: processClicked,
  target: processItems,
})

const App = () => (
  <section>
    <header>
      <h1>Jobs list</h1>
    </header>
    <button onClick={processClicked}>run tasks</button>
    <button onClick={resetItems}>reset</button>
    <ol>
      {useList(items$, ({status}) => (
        <li>{status}</li>
      ))}
    </ol>
  </section>
)

ReactDOM.render(<App />, document.getElementById('root'))

Try it

effector 20.3.1

Fix edge case when clearNode been called on store belonged to certain domain led to the removal of the entire domain

effector-react 20.4.0

Add support for keys field in useList. By default, useList rerenders only when some of its items was changed. Howewer, sometimes we need to update items when some external value (e.g. props field or state of another store) is changed. In such cases we need to tell react about our dependencies and pass keys explicitly.

import React from 'react'
import ReactDOM from 'react-dom'

import {createEvent, createStore, restore} from 'effector'
import {useStore, useList} from 'effector-react'

const renameUser = createEvent()
const user = restore(renameUser, 'alice')
const friends = createStore(['bob'])
const List = () => {
  const userName = useStore(user)
  return useList(friends, {
    keys: [userName],
    fn: friend => (
      <div>
        {friend} is a friend of {userName}
      </div>
    ),
  })
}
ReactDOM.render(<List />, document.getElementById('root'))
// => <div> bob is a friend of alice </div>
setTimeout(() => {
  renameUser('carol')
  // => <div> bob is a friend of carol </div>
}, 500)

Try it

effector 20.3.0

Add shortName to domains

import {createDomain} from 'effector'
const domain = createDomain('feature')
console.log(domain.shortName)
// => feature

Try it

Add history to domains with read-only sets of events, effects, stores and subdomains

import {createDomain} from 'effector'
const domain = createDomain()
const eventA = domain.event()
const storeB = domain.store(0)
console.log(domain.history)
// => {stores: Set{storeB}, events: Set{eventA}, domains: Set, effects: Set}

Try it

effector-vue 20.2.0

Add support for object shape

const counter = createStore(0)

new Vue({
  effector: {
    counter, // would create `counter` in template
  },
})

effector 20.2.0

Add support for domains to clearNode

import {createDomain, clearNode} from 'effector'
const root = createDomain()
const child = root.domain()
clearNode(child)

Add .sid - stable hash identifier for events, effects, stores and domains, preserved between environments, to handle client-server interaction within the same codebase.

/* common.js */

import {createEffect} from 'effector'

export const getUser = createEffect({sid: 'GET /user'})
console.log(getUsers.sid)
// => GET /user

/* worker.js */

import {getUsers} from './common'

getUsers.use(userID => fetch(userID))

getUsers.done.watch(({result}) => {
  postMessage({sid: getUsers.sid, result})
})

onmessage = async ({data}) => {
  if (data.sid !== getUsers.sid) return
  getUsers(data.userID)
}

/* client.js */

import {createEvent} from 'effector'
import {getUsers} from './common'

const onMessage = createEvent()

const worker = new Worker('worker.js')
worker.onmessage = onMessage

getUsers.use(
  userID =>
    new Promise(rs => {
      worker.postMessage({sid: getUsers.sid, userID})
      const unwatch = onMessage.watch(({data}) => {
        if (data.sid !== getUsers.sid) return
        unwatch()
        rs(data.result)
      })
    }),
)

The key is that sid can be autogenerated by effector/babel-plugin with default config and it will be stable between builds

See example project

Add support for implicit void params in createEffect for typescript #106

const handler = () => console.log()

const effect = createEffect({handler})

effect()

Fix bug with cannot read property .toString of undefined error during store initialization

effector-react 20.3.0

Add support for react hooks in createComponent

effector-react 20.2.2, effector-vue 20.1.2

effector-react, effector-vue and effector itself have compat builds for compatibility with old devices without babel. In such versions, it should import effector/compat, not just effector (Fix #173)

effector 20.1.2

Allow typescript to refine type of payload if event.filter({fn}) got a predicate function as a callback PR

import {createEvent} from 'effector'

const event = createEvent<string | number>()

const isString = (value: any): value is string => typeof value === 'string'
const isNumber = (value: any): value is number => typeof value === 'number'

const str = event.filter({fn: isString}) // Event<string>
const num = event.filter({fn: isNumber}) // Event<number>

str.watch(value => value.slice()) // OK now
num.watch(value => value.toFixed(2)) // OK now

Allow typescript to refine type with is methods PR

import {is} from 'effector'

//result has type Event<any> | void
function getEvent(obj: unknown) {
  if (is.event(obj)) return obj
  if (is.store(obj)) return obj.updates
}

Add new fields to definition of graph nodes (discussion)

effector 20.1.1

Add support for IE11 to effector/compat
Fix flow typings for sample
Allow effector/babel-plugin to work in browser

effector-react 20.2.1, effector-vue 20.1.1

Add support for IE11 to effector-react/compat and effector-vue/compat

effector 20.1.0

Add effector/compat module to use with Smart TV (Chrome 47) apps without babel (fix #152). Starting with this release, the library code is tested by browserstack.com for compatibility with our targets, including smart tv
Improve typescript typings for sample (thanks @abliarsar) (PR #156)
Fix webpack issue, which generated incorrect code with some ancient targets (IE10)

effector-react 20.2.0

Add effector-react/compat module to use with Smart TV (Chrome 47) apps without babel

effector-vue 20.1.0

Add effector-vue/compat module to use with Smart TV (Chrome 47) apps without babel

effector-react 20.1.1

Add useList for efficient rendering of store lists

import React from 'react'
import ReactDOM from 'react-dom'

import {createStore} from 'effector'
import {useList} from 'effector-react'

const list = createStore([
  {name: 'alice', age: 21},
  {name: 'bob', age: 20},
  {name: 'carol', age: 22},
])

const List = () => {
  // note that we don't need keys here any more
  const users = useList(list, ({name}, i) => (
    <div>
      {i}) {name}
    </div>
  ))
  return <div>{users}</div>
}

ReactDOM.render(<List />, document.getElementById('root'))

Try it

effector-react 20.0.5

Fix irrelevant react memory leak warning in a few cases

effector-react 20.0.4

Fix a bug in useStore with lack of store updates triggered by react hooks in children components

effector-react 20.0.3

Allow as const typescript assertion for useStoreMap keys. It helps us to infer type for fn arguments

import React from 'react'
import {createStore} from 'effector'
import {useStoreMap} from 'effector-react'

type User = {
  username: string
  email: string
  bio: string
}

const users = createStore<User[]>([
  {
    username: 'alice',
    email: 'alice@example.com',
    bio: '. . .',
  },
  {
    username: 'bob',
    email: 'bob@example.com',
    bio: '~/ - /~',
  },
  {
    username: 'carol',
    email: 'carol@example.com',
    bio: '- - -',
  },
])

export const UserProperty = ({id, field}: {id: number; field: keyof User}) => {
  const value = useStoreMap({
    store: users,
    keys: [id, field] as const,
    fn: (users, [id, field]) => users[id][field] || null,
  })
  return <div>{value}</div>
}

In typescript versions below 3.4, you can still use an explicit type assertion

import React from 'react'
import {createStore} from 'effector'
import {useStoreMap} from 'effector-react'

type User = {
  username: string
  email: string
  bio: string
}

const users = createStore<User[]>([
  {
    username: 'alice',
    email: 'alice@example.com',
    bio: '. . .',
  },
  {
    username: 'bob',
    email: 'bob@example.com',
    bio: '~/ - /~',
  },
  {
    username: 'carol',
    email: 'carol@example.com',
    bio: '- - -',
  },
])

export const UserProperty = ({id, field}: {id: number; field: keyof User}) => {
  const value = useStoreMap({
    store: users,
    keys: [id, field] as [number, keyof User],
    fn: (users, [id, field]) => users[id][field] || null,
  })
  return <div>{value}</div>
}

as const in typescript docs

effector-react 20.0.2

Fix bug with additional rerender in case of useStore argument change

effector-react 20.0.1

Fix flow typings for useStoreMap

effector 20.0.0

Add merge for merging events

import {createEvent, merge} from 'effector'
const foo = createEvent()
const bar = createEvent()
const baz = merge([foo, bar])
baz.watch(v => console.log('merged event triggered: ', v))

foo(1)
// => merged event triggered: 1
bar(2)
// => merged event triggered: 2

Try it

Add split for pattern-matching over events

import {createEvent, split} from 'effector'
const message = createEvent()

const messageByAuthor = split(message, {
  bob: ({user}) => user === 'bob',
  alice: ({user}) => user === 'alice',
})
messageByAuthor.bob.watch(({text}) => {
  console.log('[bob]: ', text)
})
messageByAuthor.alice.watch(({text}) => {
  console.log('[alice]: ', text)
})

message({user: 'bob', text: 'Hello'})
// => [bob]: Hello
message({user: 'alice', text: 'Hi bob'})
// => [alice]: Hi bob

/* default case, triggered if no one condition met */
const {__: guest} = messageByAuthor
guest.watch(({text}) => {
  console.log('[guest]: ', text)
})
message({user: 'unregistered', text: 'hi'})
// => [guest]: hi

Try it

Allow clearNode to automatically dispose all related intermediate steps

import {createEvent, clearNode} from 'effector'
const source = createEvent()
const target = source.map(x => {
  console.log('intermediate step')
  return x
})
target.watch(x => console.log('target watcher'))
source()
// => intermediate step
// => target watcher
clearNode(target)
source() // ~ no reaction ~

Try it

Fix promise warning for effects
Add effect.finally

import {createEffect} from 'effector'
const fetchApi = createEffect({
  handler: n =>
    new Promise(resolve => {
      setTimeout(resolve, n, `${n} ms`)
    }),
})
fetchApi.finally.watch(response => {
  console.log(response)
})

await fetchApi(10)
// => {status: 'done', result: '10 ms', params: 10}

// or

// => {status: 'fail', error: Error, params: 10}

Try it

Add types for createEvent with config instead of string
Add types for createEffect with config instead of string
Add event.filterMap as new alias for event.filter(fn)
Remove extract, withProps, is.* re-exports

effector-react 20.0.0

Removed unstable_createStoreProvider

effector-vue 20.0.0

Vue adapter for effector 20

effector-react 19.1.2

Add useStoreMap hook to select part from a store. Motivation

import {createStore} from 'effector'
import {useStore, useStoreMap} from 'effector-react'
import React from 'react'
import ReactDOM from 'react-dom'

const User = ({id}) => {
  const user = useStoreMap({
    store: user$,
    keys: [id],
    fn: (users, [id]) => users[id],
  })
  return (
    <div>
      {user.name} ({user.age})
    </div>
  )
}

const UserList = () => useStore(userID$).map(id => <User id={id} key={id} />)

const user$ = createStore({
  alex: {age: 20, name: 'Alex'},
  john: {age: 30, name: 'John'},
})

const userID$ = user$.map(users => Object.keys(users))

ReactDOM.render(<UserList />, document.getElementById('root'))

Try it

effector 19.1.0

Add support for event.filter with common predicate functions

import {createEvent} from 'effector'

const event = createEvent()

// that event will be triggered only when fn returns true
const filtered = event.filter({
  fn: x => x > 0,
})

filtered.watch(x => console.log('x =', x))

event(-2) // nothing happens
event(2) // => x = 2

effector-vue 19.0.1

Fix typescript typings #116

effector, effector-react, effector-vue 19.0.0

To indicate the stability of the project, we adopting semantic versioning and happy to announce version 19.0.0 for all packages. And to make the transition easier, that release contains no breaking changes; simple replacement of “^0.18.*” to “^19.0.0” is safe for sure ☄️

effector 0.18.10-0.18.11

Implement event store.updates, representing updates of given store. Use case: watchers, which will not trigger immediately after creation (unlike store.watch)

see spec for store.updates in tests

import {createStore, is} from 'effector'

const clicksAmount = createStore(0)
is.event(clicksAmount.updates) // => true

clicksAmount.watch(amount => {
  console.log('will be triggered with current state, immediately, sync', amount)
})

clicksAmount.updates.watch(amount => {
  console.log('will not be triggered unless store value is changed', amount)
})

Try it

effector 0.18.9

Allow clearNode to erase information from the node itself, in addition to the existing opportunity to erase subscribers (thanks @artalar)

use cases for clearNode checked in tests

effector 0.18.7-0.18.8

Add support for passing multiply items at once in store.reset

import {createStore, createEvent} from 'effector'

const firstTrigger = createEvent()
const secondTrigger = createEvent()

const target = createStore(0).reset(firstTrigger, secondTrigger)

Add support for createEvent and createEffect with config (see next code example)
Add .pending property for effects

import {createEffect} from 'effector'
import {createComponent} from 'effector-react'
import React from 'react'
const fetchApi = createEffect({
  handler: n => new Promise(resolve => setTimeout(resolve, n)),
})

fetchApi.pending.watch(console.log)

const Loading = createComponent(
  fetchApi.pending,
  (props, pending) => pending && <div>Loading...</div>,
)

fetchApi(5000)

it’s a shorthand for common use case

import {createEffect, createStore} from 'effector'

const fetchApi = createEffect()

//now you can use fetchApi.pending instead
const isLoading = createStore(false)
  .on(fetchApi, () => true)
  .on(fetchApi.done, () => false)
  .on(fetchApi.fail, () => false)

Try it

Introduce sample. Sample allows to integrate rapidly changed values with common ui states

import {createStore, createEvent, sample} from 'effector'
import {createComponent} from 'effector-react'
import React from 'react'

const tickEvent = createEvent()
const tick = createStore(0).on(tickEvent, n => n + 1)

setInterval(tickEvent, 1000 / 60)

const mouseClick = createEvent()
const clicks = createStore(0).on(mouseClick, n => n + 1)

const sampled = sample(tick, clicks, (tick, clicks) => ({
  tick,
  clicks,
}))

const Monitor = createComponent(sampled, (props, {tick, clicks}) => (
  <p>
    <b>tick: </b>
    {tick}
    <br />
    <b>clicks: </b>
    {clicks}
  </p>
))

const App = () => (
  <div>
    <Monitor />
    <button onClick={mouseClick}>click to update</button>
  </div>
)

see sample in action here

Sampling (signal processing)

Add babel plugin for automatic naming of events, effects and stores (useful for identifying resources with SSR)
Add babel plugin for automatic displayName for react components

import {createStore, createEvent} from 'effector'
import {createComponent} from 'effector-react'
import React from 'react'

const title = createStore('welcome')

console.log('store.shortName', title.shortName)
// store.shortName title

const clickTitle = createEvent()

console.log('event.shortName', clickTitle.shortName)
// store.shortName clickTitle

const Title = createComponent(title, (props, title) => <h1>{title}</h1>)

console.log('Component.displayName', Title.displayName)
// Component.displayName Title

Plugins are available out from a box

.babelrc:

{
  "plugins": ["effector/babel-plugin", "effector/babel-plugin-react"]
}

see plugins in action

Add support for passing events and effects to watchers

import {createStore, createEvent} from 'effector'

const updates = createEvent()
const state = createStore(0)
state.watch(updates)

Improve execution order for sync effects
Improve typescript typings for createApi (#102)

effector-react 0.18.10

Add initial props factory to createComponent

import {users} from './feature'

const UserItem = createComponent(
  initialProps => users.map(users => users[initialProps.id]),
  (_, user) => {
    return <div>{user.username}</div>
  },
)

const UserList = createComponent(users, (_, users) => {
  return users.map(user => <TodoItem key={user.id} id={user.id} />)
})

Implicitly convert objects to createStoreObject in createComponent

const deposit = createEvent()
const username = createStore('zerobias')
const balance = createStore(0)

const Profile = createComponent(
  {username, balance},
  (_, {username, balance}) => {
    return (
      <div>
        Hello, {username}. Your balance is {balance}
        <button onClick={deposit}>Deposit</button>
      </div>
    )
  },
)

Add mounted and unmounted events to components created by createComponent

import {counter, increment} from './feature'

const Counter = createComponent(counter, (_, state) => {
  return (
    <div>
      {state}
      <button onClick={increment}>+</button>
    </div>
  )
})

Counter.mounted.watch(({props, state}) => {
  counter.on(increment, s => s + 1)
})

Counter.unmounted.watch(({props, state}) => {
  counter.off(increment)
})

Replace useLayoutEffect with useIsomorphicLayoutEffect to support server-side rendering

effector-react 0.18.9

Replace useEffect with useLayoutEffect in useStore hook to response to state changes immediately

0.18.5-0.18.6

Optimize combined stores: no intermediate steps no more

import {createStore, createEvent, createStoreObject, combine} from 'effector'

const field = createStore('')
const isEmpty = field.map(value => value.length === 0)
const isTooLong = field.map(value => value.length > 12)
const isValid = combine(
  isEmpty,
  isTooLong,
  (isEmpty, isTooLong) => !isEmpty && !isTooLong,
)

const updateField = createEvent('update field value')

field.on(updateField, (state, upd) => upd.trim())

createStoreObject({
  field,
  isEmpty,
  isTooLong,
  isValid,
}).watch(data => {
  console.log(data)
})

// => {field: '', isEmpty: true, isTooLong: false, isValid: false}

updateField('bobby')

// => {field: 'bobby', isEmpty: false, isTooLong: false, isValid: true}

Use the new kernel. Provide improved eventual consistency: any side effects will be triggered only after performing all pure computations
Add is namespace for all type validators

import {createStore, createEvent, is} from 'effector'
const store = createStore('value')
const event = createEvent('some event')

is.store(store) // => true
is.event(store) // => false
is.unit(store) // => true

is.store(event) // => false
is.event(event) // => true
is.unit(event) // => true

is.store(null) // => false
is.event(null) // => false
is.unit(null) // => false

Add clearNode to break references and subscriptions between events, stores, etc
Add support for custom datatypes by making step constructors, createNode and launch functions public

import {createNode, launch, step, createStore} from 'effector'

const target = createStore(0)
target.watch(n => console.log('current n = ', n))
// => current n = 0

const customNode = createNode({
  scope: {max: 100, lastValue: -1, add: 10},
  child: [target], // you can forward later as well
  node: [
    step.compute({
      fn: (arg, {add}) => arg + add,
    }),
    step.filter({
      fn: (arg, {max, lastValue}) => arg < max && arg !== lastValue,
    }),
    step.compute({
      fn(arg, scope) {
        scope.lastValue = arg
        return arg
      },
    }),
  ],
})

launch(customNode, 3)
// => current n = 13
launch(customNode, 95)
// no reaction, as 95 + 10 > 100
launch(customNode, 5)
// => current n = 15
launch(customNode, 5)
// no reaction, as we filtered it out with step.filter

Fix fromObservable, ensure it works with redux as a typical library with Symbol.observable support

import {fromObservable} from 'effector'
import * as redux from 'redux'

const INCREMENT_STATE = 'INCREMENT_STATE'
const reduxStore = redux.createStore((state = 1, action) => {
  switch (action.type) {
    case INCREMENT_STATE:
      return state + 1
    default:
      return state
  }
})

const updateEvent = fromObservable(reduxStore)
updateEvent.watch(state => {
  console.log('redux state = ', state)
})

reduxStore.dispatch({type: INCREMENT_STATE})
// => redux state = 1

Fix version, now it always equals version in package.json

import {version} from 'effector'
console.log(version)
// => 0.18.6

Add support forwarding to effects

import {createEffect, createEvent, forward} from 'effector'

const trigger = createEvent()

const sideEffect = createEffect('side-effect', {
  async handler(args) {
    await new Promise(rs => setTimeout(rs, 500))
    console.log('args: ', args)
  },
})

forward({
  from: trigger,
  to: sideEffect,
})

trigger('payload')
// ~ after 500 ms
// => args: payload

0.18.3-0.18.4

Add version variable to public exports

import {version} from 'effector'
console.log(version)

Add effect handler to domain 4c6ae8
Add Unit<T> as common interface implemented by Event, Effect and Store
Add isStore, isEvent, isEffect and isUnit validators

import {createStore, createEvent, isStore, isEvent, isUnit} from 'effector'
const store = createStore('value')
const event = createEvent('some event')

isStore(store) // => true
isEvent(store) // => false
isUnit(store) // => true

isStore(event) // => false
isEvent(event) // => true
isUnit(event) // => true

isStore(null) // => false
isEvent(null) // => false
isUnit(null) // => false

Add extended createStore with config

import {createStore} from 'effector'
const store = createStore('value', {
  name: 'value store',
})

Publish babel-plugins
Improve naming for chrome performance timeline
Fix typescript typings #45
Fix event.prepend bug #35

0.18.2

Fix webpack usage issue. To prevent this in a future, webpack integration test was added.
Improve typescript typings for createApi. This code example became type checked

import {createStore, createApi} from 'effector'

const text = createStore('')

const {addMessage, cut} = createApi(text, {
  addMessage: (text, message) => text + `\n` + message
  cut: (text, {fromIndex, size}) => text.slice(fromIndex, fromIndex + size),
})

Add umd bundle to npm. Therefore, you can use cdn to include library without bundlers

<!DOCTYPE html>
<html>
  <head>
    <script src="https://unpkg.com/effector@0.18.2/effector.umd.js"></script>
  </head>
  <body>
    <script>
      const header = document.createElement('h1')
      document.body.appendChild(header)
      const text = effector.createStore('hello')
      text.watch(str => (header.innerHTML = str))
    </script>
  </body>
</html>

0.18.1

Add forward: common function for forwarding updates and events

import {forward} from 'effector'
const unsubscribe = forward({
  from: Event | Store,
  to: Event | Store | Effect,
})

add support for storages in store.on

import {createStore} from 'effector'
const name = createStore('name')
const counter = createStore(0).on(name, (count, name) => count++)

Allow to pass {handler: Function} as second argument to createEffect

import {createEffect} from 'effector'
const callApi = createEffect('call api', {
  async handler(url) {
    const res = await fetch(url)
    return res
  },
})

Make effect.use return the same effect instead of void (ability to chain method calls)

import {createEffect} from 'effector'
const callApi = createEffect('call api').use(url => fetch(url))

0.18.0

Log events into Chrome devtools performance timeline
Add notifications about errors inside computation chain
Add store.defaultState property
effector-react: Add createComponent
Make withProps static function
Make effect return plain promise

0.18.0-beta.10

Add Gate

import {type Gate, createGate} from 'effector-react'
const AppGate = createGate('app')
const MainPageGate = AppGate.childGate('main page')

export default ({isLoading, meta}) => (
  <div>
    Application
    <AppGate isLoading={isLoading} />
    {!isLoading && (
      <div>
        Main page
        <MainPageGate meta={meta} />
      </div>
    )}
  </div>
)
AppGate.state.watch(({isLoading}) => isLoading)

0.17.7

Keep and replay the whole domain history for every new hook

0.17.6

Add domain hooks for handle new events, effects or stores in domain.

import {createDomain} from 'effector'
const mainPage = createDomain('main page')
mainPage.onCreateEvent(event => {
  console.log('new event: ', event.getType())
})
mainPage.onCreateStore(store => {
  console.log('new store: ', store.getState())
})
const mount = mainPage.event('mount')
// => new event: main page/mount

const pageStore = mainPage.store(0)
// => new store: 0

Improve TypeScript typings

0.17.5

Add ability to use createEvent, createEffect and createDomain without arguments (omit name)
Fix wrong order of effect names
Add createWrappedDomain to watch all nested events and updates
Add extract to watch only part of nested storages
Deprecate .epic method (library supports symbol-observable, so assumed that most.from(event) or Observable.Of(store) covered all use cases)

0.17.4

effector-react: Add check for mounting of store consumer
Add effect.use.getCurrent() method to get current used function
Improve type inference in flow typing for createStoreObject
Improve public ts and flow typings

0.17.3

Fix effector-react typings
Build with node 6 target, add engine field to package.json
Add warning dependency

0.17.2

Memoize store.map and store updates

0.17.0

Added sync graph reduction engine (it’s internal)
Added store updates memoization
Introduced effector-react

0.16.0

Removed most-subject dependency
New api

0.15.0-rc.2

Add AVar: low-level interface for asynchronous variables
Clean up builds before publishing
Add types dir into npm build

0.14.0

Add independent createStore method
Replace console.warn with console.error in warnings
Make reducers full-featured store elements (add .get(), .set(x) and .map(fn) methods)
Add observable declaration to effects, events and reducers, which allow interop in this way: from(effect)

0.13.0

Build via rollup
New module architechture

0.12.0

Exclude coverage from npm build
Rename mill to collect
Rename joint to combine

0.11.1

Remove source files from npm release

0.11.0

Add support for sync functions in .use
breaking Rename config option effectImplementationCheck to unused

0.10.2

Fix overriding of flow modules

0.10.0

breaking Removed rootDomain alias for createRootDomain
Fixed duplication of typeConstant events
Added sync event propagation
Catching of watch function errors
Added warning to port errors
Added type aliases DomainAuto, EventAuto and EffectAuto
Added mill fluent “AND” reducer combinator

import {mill, type MillType, type Reducer} from 'effector'

type A = 'foo'
type B = 'bar'
declare var reducerA: Reducer<A>
declare var reducerB: Reducer<B>

const tuple: MillType<A, B> = mill()
  .and(reducerA)
  .and(reducerB)

const union: Reducer<{
  a: A,
  b: B,
  staticField: string,
}> = tuple.joint((a: A, b: B) => ({
  a,
  b,
  staticField: 'its ok',
}))

0.9.1

Added hot reload support for root domains
Added support for dispatching halt action

import {createHaltAction} from 'effector'

store.dispatch(createHaltAction()) //This store will be unsubscribed

0.9.0

First stable version

Before 0.9.0

Proof of concept