Changelog

• Add type support for arrays in sample target (PR #284, #445)

sample({
  clock: clickValidate,
  source: $formFields,
  target: [validateForm, sendStatsFx],
})

• Add support for case functions, case stores and matcher stores to split. Case functions and stores will choose target case by its name, matcher stores are boolean stores which indicate whether to choose given case

const source = createEvent()
const even = createEvent()
const odd = createStore(0)

split({
  source,
  // case function
  match(n) {
    if (n % 2 === 0) return 'even'
    return 'odd'
  },
  cases: {
    even,
    odd,
  }
})

const $currentPage = createStore('dashboard')

split({
  source,
  // case store
  match: $currentPage,
  cases: {
    dashboard: even,
    __: odd,
  }
})

const tryUpdatePage = createEvent()
const updatePageFx = createEffect()



const $hasWriteAccess = createStore(false)


split({
  source: tryUpdatePage,
  match: {
    // matcher store
    admin: $hasWriteAccess
  },
  cases: {
    admin: updatePageFx,
  }
})

• Add updateFilter config field to createStore to skip arbitrary store updates (discussion #428)

const $playerPosition = createStore({x: 0, y: 0}, {
  updateFilter: (update, current) => update.x !== current.x
})

• Add support for sample with clock without source. For example, it useful in cases when clock is array of units and no source stores is needed

sample({
  clock: [fx1.doneData, fx2.doneData],
  fn: data => ({url: '/stats', data})
  target: fetchFx,
})

• Add support for clock to guard to improve developer expirience in cases when update trigger (clock field) and data source (source field) are different things

guard({
  clock: validateForm,
  source: $formFields,
  filter: formFields => validator(formFields),
  target: submitFormFx,
})

• Add addNames field to babel plugin (PR #450)

• Add type support for Scope to clearNode (issue #441)

• Add compositeName to Domain typings, making it consistent with other units

• Add EventPayload and UnitValue type helpers (PR #434)

• Improve various edge cases with fork api and serialization

• Improve typechecking for attach (issue #439)

• Fix various type issues in sample and guard typings

• Add support for scopes to hydrate, to provide a way to fill additional values to existing scope (happens during SSG navigation in next.js)

• Improve prepend type inference (PR #415 (thanks @doasync))

• Add support for user-defined factories in fork api. Starting from this release, application developers can use their own functions and be sure that their content will be properly serialized and hydrated by fork api. New field factories in effector/babel-plugin accepts array of module names which exports will be treated as custom factories therefore each function call will provide unique prefix for sid properties of units inside them

{
  "plugins": [
    [
      "effector/babel-plugin",
      {
        "factories": ["src/createEffectStatus", "~/createCommonPending"]
      }
    ]
  ]
}

import {rootDomain} from './rootDomain'

export function createEffectStatus(fx) {
  const $status = rootDomain
    .createStore('init')
    .on(fx.finally, (_, {status}) => status)
  return $status
}

import {createEffectStatus} from './createEffectStatus'
import {fetchUserFx, fetchFriendsFx} from './api'

export const $fetchUserStatus = createEffectStatus(fetchUserFx)
export const $fetchFriendsStatus = createEffectStatus(fetchFriendsFx)

Import createEffectStatus from './createEffectStatus' was treated as factory function so each store created by it has its own sid and will be handled by serialize independently, although without factories they will share the same sid

factories in documentation

• Add user-friendly unit name in fork api error messages when given unit is not found in scope. This improves error messages in both effector and effector-react

• Add validation for values and handlers fields in fork and for values field in hydrate

• Add type support for createEffect<typeof handler, Error>(handler) to infer Params and Done types from given handler and provide custom Fail type at the same time

createEffect and custom errors in documentation

• Improve guard return type inference (PR #406 (thanks @doasync))

• Fix void params support for createEffect(name, config) (issue #404)

• Allow to use Event<void> in cases when only () => void is accepted (PR #400 (thanks @doasync))

• Add support for merge to effector/babel-plugin

• Add support for attach({effect}) to create effect which will call effect with params as it is. That allow to create separate effects with shared behavior (PR #396 and #397 (thanks @sergeysova and @oas89))

• Add reactSsr option to effector/babel-plugin to replace imports from effector-react to effector-react/ssr. Useful for building both server-side and client-side builds from the same codebase

• Add support for return status to allSettled. When allSettled is called with Effect, it return object with value and status fields (discussion)

import {createDomain, fork, allSettled} from 'effector'
const app = createDomain()
const fx = app.createEffect(() => 'ok')
const result = await allSettled(fx, {scope: fork(app)})
// => {status: 'done', value: 'ok'}

Try it

• Allow to expicitly define return/error types in createEffect(handler)

const fx = createEffect<number, string, Error>(x => x.toString())
// fx has type Effect<number, string, Error>

• Add types for domain.effect(handler)

• Fix effector/babel-plugin behavior in case when methods like createStore are imported from unrelated library and should be ignored. Import library could be defined by importName config field

• Improve fork api support for watchers

• Add support for createEffect(handler)

createEffect(handler) in documentation

import {createEffect} from 'effector'

const fetchUserReposFx = createEffect(async ({name}) => {
  const url = `https://api.github.com/users/${name}/repos`
  const req = await fetch(url)
  return req.json()
})

fetchUserReposFx.done.watch(({params, result}) => {
  console.log(result)
})

await fetchUserReposFx({name: 'zerobias'})

Try it

• Add support for attach({source, effect}) without mapParams: in case with source and effect only, inner effect will be triggered with source values

attach({effect, source}) in documentation

import {createStore, createEffect, attach} from 'effector'
const request = createEffect()
const token = createStore('')
const secureRequest = attach({effect: request, source: token})

it’s a shorthand for common use case:

import {createStore, createEffect, attach} from 'effector'
const request = createEffect()
const token = createStore('')
const secureRequest = attach({
  effect: request,
  source: token,
  mapParams: (_, source) => source,
})

Try it

• Handle throws in attach mapParams field: errors happened in mapParams function will force attached effect to fail
• Add babel plugin support for split and createApi
• Add name field to attach typings
• Add .filter and .filterMap to effect typings (PR #376)
• Improve config validation for forward, attach, sample and guard: attempt to call these methods without arguments will lead to error with user-friendly description
• Improve fork api support for stores and events

• Add array support for sample clock field which acts like a merge call

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

const showNotification = createEvent<string>()
const trigger = createEvent()
const fx = createEffect()
const store = createStore('')

// array of units in clock
sample({
  source: store,
  clock: [trigger, fx.doneData],
  target: showNotification,
})

// merged unit in clock
sample({
  source: store,
  clock: merge([trigger, fx.doneData]),
  target: showNotification,
})

• Improve ide type hints support for sample in case of config form
• Add package.json to package exports field (read more in nodejs documentation)

• Add onlyChanges option to serialize to ignore stores which didn’t changed in fork (prevent default values from being carried over network)

• Add type helpers for stores and effects: StoreValue, EffectParams, EffectResult and EffectError

import {
  createStore,
  createEffect,
  StoreValue,
  EffectParams,
  EffectResult,
} from 'effector'

const username = createStore('guest')

const getUserFX = createEffect<number, {name: string}>()

// string
type Username = StoreValue<typeof username>

// number
type GetUserParams = EffectParams<typeof getUserFX>

// {name: string}
type User = EffectResult<typeof getUserFX>

• Allow domain.createEffect to infer type from given handler (that feature was already implemented for createEffect method), this code now typechecked as expected:

import {createDomain} from 'effector'

const app = createDomain()

const voidFx = app.createEffect({
  async handler() {},
})

await voidFx()

• Allow to call allSettled with void units without params field, this code now typechecked as expected:

import {createDomain, fork, allSettled} from 'effector'

const app = createDomain()

const voidFx = app.createEffect({
  async handler() {},
})

voidFx()

const scope = fork(app)

await allSettled(voidFx, {scope})

• Improve native es modules support, add conditional exports declarations

• Add object form of split for pattern-matching without additional forwards

split in documentation

import {split, createEffect, createEvent} from 'effector'
const messageReceived = createEvent()
const showTextPopup = createEvent()
const playAudio = createEvent()
const reportUnknownMessageType = createEffect({
  handler({type}) {
    console.log('unknown message:', type)
  },
})

split({
  source: messageReceived,
  match: {
    text: msg => msg.type === 'text',
    audio: msg => msg.type === 'audio',
  },
  cases: {
    text: showTextPopup,
    audio: playAudio,
    __: reportUnknownMessageType,
  },
})

showTextPopup.watch(({value}) => {
  console.log('new message:', value)
})

messageReceived({
  type: 'text',
  value: 'Hello',
})
// => new message: Hello
messageReceived({
  type: 'image',
  imageUrl: '...',
})
// => unknown message: image

Try it

You can match directly to store api as well:

import {split, createStore, createEvent, createApi} from 'effector'

const textContent = createStore([])

const messageReceived = createEvent()

split({
  source: messageReceived,
  match: {
    text: msg => msg.type === 'text',
    audio: msg => msg.type === 'audio',
  },
  cases: createApi(textContent, {
    text: (list, {value}) => [...list, value],
    audio: (list, {duration}) => [...list, `audio ${duration} ms`],
    __: list => [...list, 'unknown message'],
  }),
})

textContent.watch(messages => {
  console.log(messages)
})

messageReceived({
  type: 'text',
  value: 'Hello',
})
// => ['Hello']
messageReceived({
  type: 'image',
  imageUrl: '...',
})
// => ['Hello', 'unknown message']
messageReceived({
  type: 'audio',
  duration: 500,
})
// => ['Hello', 'unknown message', 'audio 500 ms']

Try it

• Merge effector/fork into effector. Now all methods required for SSR are exported from the library itself, making effector/fork an alias
• Make Scope type alias for Fork
• Add support for es modules: import {createStore} from 'effector/effector.mjs'
• Effect without a handler now throws an error during a call instead of calling console.error with undefined return, which was violating the type of effect
• Remove restore aliases, event.filter(fn) alias for event.filterMap(fn), greedy in sample as separate last argument and unused blocks and Kind

• Add effects created via attach to domain effects, allowing these effects to be called within other effects when using fork

import {createDomain, attach} from 'effector'
import {fork, allSettled} from 'effector/fork'

const app = createDomain()

const add = app.createEffect({handler: _ => _})

const count = app.createStore(2).on(add.doneData, (x, y) => x + y)

const addWithCurrent = attach({
  source: count,
  effect: add,
  mapParams: (params, current) => params + current,
})

const start = app.createEffect({
  async handler(val) {
    await addWithCurrent(val)
  },
})

const scope = fork(app)

await allSettled(start, {
  scope,
  params: 3,
})

console.log(scope.getState(count))
// => 7

Try it

• Add validation for combine first argument which should be store, object with stores or array with stores PR #362 (thanks @doasync)

• Add validation for event.watch watcher, this code now throw error as expected:

import {createEvent} from 'effector'

const trigger = createEvent()

trigger.watch(NaN)
// => Error: .watch argument should be a function

Try it

• Add support for nested effect calls in forked scope. Parallel requests are supported as well

import {createDomain, forward} from 'effector'
import {fork, allSettled} from 'effector/fork'

const app = createDomain()

const addWord = app.createEffect({handler: async word => word})
const words = app
  .createStore([])
  .on(addWord.doneData, (list, word) => [...list, word])

const start = app.createEffect({
  async handler(word) {
    await addWord(`${word}1`)
    await addWord(`${word}2`)
    return word
  },
})

const next = app.createEffect({
  async handler(word) {
    await Promise.all([addWord(`${word}3`), addWord(`${word}4`)])
  },
})

forward({from: start.doneData, to: next})

const scopeA = fork(app)
const scopeB = fork(app)
const scopeC = fork(app)

await Promise.all([
  allSettled(start, {
    scope: scopeA,
    params: 'A',
  }),
  allSettled(start, {
    scope: scopeB,
    params: 'B',
  }),
])

await allSettled(start, {
  scope: scopeC,
  params: 'C',
})

console.log(scopeA.getState(words))
// => [A1, A2, A3, A4]
console.log(scopeB.getState(words))
// => [B1, B2, B3, B4]
console.log(scopeC.getState(words))
// => [C1, C2, C3, C4]

Try it

• Allow createNode to call without arguments

import {createNode} from 'effector'

const node = createNode()

• Make Step type alias for Node

• Allow typescript to refine type if guard got Boolean (a function) as filter

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

type User = {name: string}

const trigger = createEvent<User | null>()
const user = createStore<User>({name: 'alice'})

guard({
  source: trigger,
  filter: Boolean,
  target: user,
})

• Add support for handlers to fork to change effect handlers for forked scope (useful for testing)

import {createDomain} from 'effector'
import {fork, hydrate, serialize, allSettled} from 'effector/fork'

//app
const app = createDomain()
const fetchFriends = app.createEffect<{limit: number}, string[]>({
  async handler({limit}) {
    /* some client-side data fetching */
    return []
  },
})
const user = app.createStore('guest')
const friends = app
  .createStore([])
  .on(fetchFriends.doneData, (_, result) => result)

/*
  test to ensure that friends value is populated
  after fetchFriends call
*/
const testScope = fork(app, {
  values: {
    [user.sid]: 'alice',
  },
  handlers: {
    [fetchFriends.sid]: () => ['bob', 'carol'],
  },
})

/* trigger computations in scope and await all called effects */
await allSettled(fetchFriends, {
  scope: testScope,
  params: {limit: 10},
})

/* check value of store in scope */
console.log(testScope.getState(friends))
// => ['bob', 'carol']

Try it

• Add support for scope.getState(store) to access to store values in forked scopes
• Fix values support for fork

• Fix additional store updates during state hydration

import {createDomain, forward} from 'effector'
import {hydrate} from 'effector/fork'

const app = createDomain()

const username = app.createStore('guest')
const saveUser = app.createEffect({
  handler(value) {
    console.log('saveUser now called only after store update', value)
  },
})

forward({
  from: username,
  to: saveUser,
})

username.updates.watch(value => {
  console.log('event watches now called only after store update', value)
})

hydrate(app, {
  values: {
    [username.sid]: 'alice',
  },
})
// no event watches triggered yet and no effects called as we just hydrating app state

Try it

• Add support for array of units to store.on (PR #328)

import {createEvent, createStore} from 'effector'

const store = createStore(0)
const changedA = createEvent()
const changedB = createEvent()

store.on([changedA, changedB], (state, params) => state + params)

store.watch(value => {
  console.log('updated', value)
})

changedA(2)
// => updated 2

changedB(2)
// => updated 4

// You can unsubscribe from any trigger
store.off(changedA)

Try it

Documentation for store.on

• Add support for array of units to store.reset to make it consistent with merge and store.on

import {createEvent, createStore} from 'effector'

const store = createStore(0)
const increment = createEvent()
const reset = createEvent()

store.on(increment, state => state + 1).reset([reset])

store.watch(state => console.log('changed', state))
// changed 0
// watch method calls its function immediately

increment() // changed 1
increment() // changed 2
reset() // changed 0

Try it

Documentation for store.reset

• Remove units erased with clearNode(unit) from their parent domain hooks and history sets

• Add ignore parameter to serialize to skip stores during app state serialization PR #325 (thanks @sergeysova)

• Fix cases with effector/babel-plugin when inability to determine unit name led to the absence of sid property

• Extend typescript support for any to void forwarding: add support for forwarding to array of void units

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

const sourceA = createEvent<string>()
const sourceB = createEvent<number>()

const targetA = createEvent<void>()
const targetB = createEffect<void, any>()

forward({
  from: sourceA,
  to: targetA,
})

forward({
  from: sourceA,
  to: [targetA, targetB],
})

forward({
  from: [sourceA, sourceB],
  to: targetA,
})

forward({
  from: [sourceA, sourceB],
  to: [targetA, targetB],
})

• Fix computed stores support for hydrate
• Fix allSettled support for effects as first argument

• Introduce attach: wrapper for effect, which allow to map effect arguments and use data from stores.

Use cases: declarative passing values from stores to effects and argument preprocessing.

import {createEffect, attach, createStore} from 'effector'

const backendRequest = createEffect({
  async handler({token, data, resource}) {
    const req = fetch(`https://example.com/api${resource}`, {
      method: 'POST',
      headers: {
        Authorization: `Bearer ${token}`,
      },
      body: JSON.stringify(data),
    })
  },
})

const requestsSend = createStore(0).on(backendRequest, total => total + 1)

requestsSend.watch(total => {
  console.log(`client analytics: sent ${total} requests`)
})

const token = createStore('guest_token')

const authorizedRequest = attach({
  effect: backendRequest,
  source: token,
  mapParams: ({data, resource}, token) => ({data, resource, token}),
})

const createRequest = resource =>
  attach({
    effect: authorizedRequest,
    mapParams: data => ({data, resource}),
  })

const getUser = createRequest('/user')
const getPosts = createRequest('/posts')

const user = await getUser({name: 'alice'})
/*
POST https://example.com/api/user
{"name": "alice"}
Authorization: Bearer guest_token
*/

// => client analytics: sent 1 requests

const posts = await getPosts({user: user.id})
/*
POST https://example.com/api/posts
{"user": 18329}
Authorization: Bearer guest_token
*/

// => client analytics: sent 2 requests

Documentation for attach

• Add noDefaults option for effector/babel-plugin for making custom unit factories with clean configuration

{
  "plugins": [
    ["effector/babel-plugin", {"addLoc": true}],
    [
      "effector/babel-plugin",
      {
        "importName": "@lib/createInputField",
        "storeCreators": ["createInputField"],
        "noDefaults": true
      },
      "createInputField"
    ]
  ]
}

// @lib/createInputField.js
import {createStore} from 'effector'
import {resetForm} from './form'

export function createInputField(defaultState, {sid, name}) {
  return createStore(defaultState, {sid, name}).reset(resetForm)
}

// src/state.js
import {createInputField} from '@lib/createInputField'

const foo = createInputField('-')
/*

will be treated as store creator and compiled to

const foo = createInputField('-', {
  name: 'foo',
  sid: 'z&si65'
})

*/

• Add type support for sample with target and without clock (in that case, source will become clock as well)

import {createStore, sample} from 'effector'

const source = createStore([{foo: 0}])
const target = createStore(0)

sample({
  source,
  target,
  fn: list => list.length,
})

Try it

• Add support for guard to babel-plugin
• Add support for forward to babel-plugin
• Add support for explicit domain.hooks calls as escape hatch for imperative adding units to given domain

• Add effect.doneData and effect.failData events with effect result and error values as shorthands for common use cases effect.done.map(({result}) => result) and effect.fail.map(({error}) => error)

import {createEffect, merge} from 'effector'

const fetchUserFx = createEffect()
const fetchFriendsFx = createEffect()

/* create event with results of any request to api */

/* new way, using .doneData events */

const apiResult = merge([fetchUserFx.doneData, fetchFriendsFx.doneData])

/* old way, using .done events */

const apiResultOld = merge([
  fetchUserFx.done.map(({result}) => result),
  fetchFriendsFx.done.map(({result}) => result),
])

Try it

Documentation for effect.doneData

Documentation for effect.failData

• 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.

• 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.

• 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

• 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

• 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

• 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

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

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

• 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

• 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

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

• 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"

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

• 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'

• 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

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

• 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

• 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

• 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)

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

• 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)

• 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

• 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

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 ☄️

• 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

• 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

• 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)

• 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

• 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

• 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>

• 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))

• 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

• 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)

• Keep and replay the whole domain history for every new hook

• 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

• 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)

• 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

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

• Memoize store.map and store updates

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

• Removed most-subject dependency
• New api

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

• 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)

• Build via rollup
• New module architechture

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

• Remove source files from npm release

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

• Fix overriding of flow modules

• 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',
}))

• 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

First stable version

Proof of concept

• Add createGate implementation to effector-react/ssr

import {createDomain} from 'effector'
import {createGate, useGate} from 'effector-react/ssr'

const app = createDomain()

const currentRouteGate = createGate({
  domain: app,
  defaultState: 'dashboard',
})

export const Layout = ({routeName, children}) => {
  useGate(currentRouteGate, routeName)
  return (
    <>
      <h1>{routeName}</h1>
      {children}
    </>
  )
}

• Add support for object and array of events to useEvent. It’s a shorthand for calling several useEvent at once (PR #425 by @sergeysova)

export function ExampleComponent() {
  const handlers = useEvent({emailChanged, passwordChanged})

  return (
    <div>
      <input onChange={handlers.emailChanged} />
      <input onChange={handlers.passwordChanged} />
    </div>
  )
}

export function ExampleComponent() {
  const [changeEmail, changePassword] = useEvent([
    emailChanged,
    passwordChanged,
  ])

  return (
    <div>
      <input onChange={changeEmail} />
      <input onChange={changePassword} />
    </div>
  )
}

• Improve native es modules support, add conditional exports declarations

• Add support for es modules
• Remove experimental Gate.isOpen plain property, which was incompatibile with concurrent mode and ssr, use Gate.status instead

Gate.status in documentation

• Export useGate with fork support from effector-react/ssr

import {useGate, useStore, Provider} from 'effector-react/ssr'
import {createGate} from 'effector-react'
import {createDomain, forward} from 'effector'
import {fork} from 'effector/fork'

const app = createDomain()

const activeChatGate = createGate({domain: app})

const getMessagesFx = app.createEffect({
  async handler({chatId}) {
    return ['hi bob!', 'Hello, Alice']
  },
})
const messagesAmount = app
  .createStore(0)
  .on(getMessagesFx.doneData, (_, messages) => messages.length)

forward({
  from: activeChatGate.open,
  to: getMessagesFx,
})

const ChatPage = ({chatId}) => {
  useGate(activeChatGate, {chatId})
  return (
    <div>
      <header>Chat {chatId}</header>
      <p>Messages total: {useStore(messagesAmount)}</p>
    </div>
  )
}
const App = ({root}) => (
  <Provider value={root}>
    <ChatPage chatId="chat01" />
  </Provider>
)

const scope = fork(app)

ReactDOM.render(<App root={scope} />, document.getElementById('root'))

Try it

• Add domain optional field to createGate which will be used to create gate units (useful for ssr)

createGate({domain}) in documentation

• Improve useList hook typings for typescript exported from effector-react/ssr by allowing usage as components’ return value (fix DefinitelyTyped issue)

• Add ability to define default Gate state in createGate via defaultState field

createGate({defaultState}) in documentation

• Remove object restriction from createGate Props type in typescript, as it becomes useless with introduction of useGate. This code now passes type checking successfully

import {createGate} from 'effector-react'

const RouteGate = createGate<string>()

const UserGate = createGate({defaultState: 'guest'})

• Improve useStore support for React.StrictMode

• Fix regression in effector-react/compat and effector-vue/compat compatibility with IE11

• Improve useList hook typings for typescript by allowing usage as components’ return value (fix DefinitelyTyped issue)

This code now works without type errors:

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

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: '- - -',
  },
])
const UserList = () => useList(users, ({username}) => <p>{username}</p>)
const App = () => (
  <div>
    <UserList />
  </div>
)

• Use shallow compare for skipping updates with useGate, thereby making it consistent with <Gate />
• Remove nesting from components, created by createContextComponent and createReactState, which previously were based on createComponent

• Add type support for stores with ReadonlyArray to useList for typescript

• Fix umd build of effector-react and effector-vue

Cdn with umd build of effector-react Cdn with umd build of effector-vue

• 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

• 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>
}

• 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

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

• 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

• Add support for react hooks in createComponent

• 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)

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

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

• 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

• Fix irrelevant react memory leak warning in a few cases

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

• 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

• Fix bug with additional rerender in case of useStore argument change

• Fix flow typings for useStoreMap

• Removed unstable_createStoreProvider

• 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

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 ☄️

• 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

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

• Add support for vue@next (vue 3)
• useStore useVModel useGate createGate see docs

• Improve native es modules support, add conditional exports declarations

• Add support for es modules

• Migrated from Vue.util.defineReactive to Vue.observable

• Effector stores will show in Vue devtools

• Cosmetic improvements for support plugin in the future.

• Now we can add some units to effector object (will be return Store<number>)

const fx = createEffect({...});
export default Vue.extend({
  effector: {
    isCompleted: fx.done
  },
  watch: {
    isCompleted(sid) {
      this.isPopupOpened = false;
    }
  },
  data: () => ({
    isPopupOpened: true,
  })
})

• Support v-model directive for scalar values

const $msg = createStore()
export default Vue.extend({
  effector: {
    $msg,
  },
})

<template>
  <input v-model="$msg" />
</template>

• Fix regression in effector-react/compat and effector-vue/compat compatibility with IE11

• Improve typescript typings for usage via Vue.extend (PR #343)

• Add support for vue component watch option (PR #313) (thanks @Fl0pZz)

import {createStore} from 'effector'
import {createComponent} from 'effector-vue'

const counter = createStore(0)

const component = createComponent(
  {
    template: '<div>{{ counter }}</div>',
    watch: {
      counter() {
        /* side-effects here */
      },
    },
  },
  {counter},
)

• Fix umd build of effector-react and effector-vue

Cdn with umd build of effector-react Cdn with umd build of effector-vue

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

• 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},
)

• 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
  },
})

• Add support for object shape

const counter = createStore(0)

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

• 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)

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

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

Vue adapter for effector 20

• Fix typescript typings #116

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 ☄️