https://github.com/dkzlv/nanostores

https://github.com/dkzlv/nanostores

Last synced: 26 days ago
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• Host: GitHub
• URL: https://github.com/dkzlv/nanostores
• Owner: dkzlv
• License: mit
• Created: 2023-08-26T13:19:44.000Z (about 1 year ago)
• Default Branch: main
• Last Pushed: 2023-08-26T13:49:37.000Z (about 1 year ago)
• Last Synced: 2023-08-26T14:51:34.845Z (about 1 year ago)
• Language: TypeScript
• Size: 2.17 MB
• Stars: 0
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • Changelog: CHANGELOG.md
  • Funding: .github/FUNDING.yml
  • License: LICENSE

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README

        
# Nano Stores



A tiny state manager for **React**, **React Native**, **Preact**, **Vue**,

**Svelte**, **Solid**, **Lit**, **Angular**, and vanilla JS.

It uses **many atomic stores** and direct manipulation.

* **Small.** Between 297 and 1045 bytes (minified and gzipped).

  Zero dependencies. It uses [Size Limit] to control size.

* **Fast.** With small atomic and derived stores, you do not need to call

  the selector function for all components on every store change.

* **Tree Shakable.** A chunk contains only stores used by components

  in the chunk.

* Designed to move logic from components to stores.

* Good **TypeScript** support.

```ts

// store/users.ts

import { atom } from 'nanostores'

export const $users = atom([])

export function addUser(user: User) {

  $users.set([...$users.get(), user]);

}

```

```ts

// store/admins.ts

import { computed } from 'nanostores'

import { $users } from './users.js'

export const $admins = computed($users, users => users.filter(i => i.isAdmin))

```

```tsx

// components/admins.tsx

import { useStore } from '@nanostores/react'

import { $admins } from '../stores/admins.js'

export const Admins = () => {

  const admins = useStore($admins)

  return (

    


      {admins.map(user => )}

    

  )

}

```




  



[Size Limit]: https://github.com/ai/size-limit

## Table of Contents

* [Smart Stores](#smart-stores)

* [Devtools](#devtools)

* [Guide](#guide)

* Integration

  * [React & Preact](#react--preact)

  * [Vue](#vue)

  * [Svelte](#svelte)

  * [Solid](#solid)

  * [Lit](#lit)

  * [Angular](#angular)

  * [Vanilla JS](#vanilla-js)

  * [Server-Side Rendering](#server-side-rendering)

  * [Tests](#tests)

* [Best Practices](#best-practices)

* [Known Issues](#known-issues)

## Install

```sh

npm install nanostores

```

## Smart Stores

* [Persistent](https://github.com/nanostores/persistent) store to save data

  to `localStorage` and synchronize changes between browser tabs.

* [Router](https://github.com/nanostores/router) store to parse URL

  and implements SPA navigation.

* [I18n](https://github.com/nanostores/i18n) library based on stores

  to make application translatable.

* [Query](https://github.com/nanostores/query) store that helps you with smart

  remote data fetching.

* [Logux Client](https://github.com/logux/client): stores with WebSocket

  sync and CRDT conflict resolution.

## Devtools

* [Logger](https://github.com/nanostores/logger) of lifecycles, changes

  and actions in the browser console.

* [Vue Devtools](https://github.com/nanostores/vue#devtools) plugin that detects

  stores and attaches them to devtools inspectors and timeline.

## Guide

### Atoms

Atom store can be used to store strings, numbers, arrays.

You can use it for objects too if you want to prohibit key changes

and allow only replacing the whole object (like we do in [router]).

To create it call `atom(initial)` and pass initial value as a first argument.

```ts

import { atom } from 'nanostores'

export const $counter = atom(0)

```

In TypeScript, you can optionally pass value type as type parameter.

```ts

export type LoadingStateValue = 'empty' | 'loading' | 'loaded'

export const $loadingState = atom('empty')

```

`store.get()` will return store’s current value.

`store.set(nextValue)` will change value.

```ts

$counter.set($counter.get() + 1)

```

`store.subscribe(cb)` and `store.listen(cb)` can be used to subscribe

for the changes in vanilla JS. For React/Vue we have extra special helpers

to re-render the component on any store changes.

```ts

const unbindListener = $counter.subscribe(value => {

  console.log('counter value:', value)

})

```

`store.subscribe(cb)` in contrast with `store.listen(cb)` also call listeners

immediately during the subscription.

[router]: https://github.com/nanostores/router

### Maps

Map store can be used to store objects with one level of depth and change keys

in this object.

To create map store call `map(initial)` function with initial object.

```ts

import { map } from 'nanostores'

export const $profile = map({

  name: 'anonymous'

})

```

In TypeScript you can pass type parameter with store’s type:

```ts

export interface ProfileValue {

  name: string,

  email?: string

}

export const $profile = map({

  name: 'anonymous'

})

```

`store.set(object)` or `store.setKey(key, value)` methods will change the store.

```ts

$profile.setKey('name', 'Kazimir Malevich')

```

Setting `undefined` will remove optional key:

```ts

$profile.setKey('email', undefined)

```

Store’s listeners will receive second argument with changed key.

```ts

$profile.listen((profile, changed) => {

  console.log(`${changed} new value ${profile[changed]}`)

})

```

### Deep Maps

Deep maps work the same as `map`, but it supports arbitrary nesting of objects

and arrays that preserve the fine-grained reactivity.

```ts

import { deepMap, listenKeys } from 'nanostores'

export const $profile = deepMap({

  hobbies: [

    {

      name: 'woodworking',

      friends: [{ id: 123, name: 'Ron Swanson' }]

    }

  ]

})

listenKeys($profile, ['hobbies[0].friends[0].name'])

// Won't fire subscription

$profile.setKey('hobbies[0].name', 'Scrapbooking')

// But this one will fire subscription

$profile.setKey('hobbies[0].friends[0].name', 'Leslie Knope')

```

### Lazy Stores

A unique feature of Nano Stores is that every state has two modes:

* **Mount:** when one or more listeners is mounted to the store.

* **Disabled:** when store has no listeners.

Nano Stores was created to move logic from components to the store.

Stores can listen for URL changes or establish network connections.

Mount/disabled modes allow you to create lazy stores, which will use resources

only if store is really used in the UI.

`onMount` sets callback for mount and disabled states.

```ts

import { onMount } from 'nanostores'

onMount($profile, () => {

  // Mount mode

  return () => {

    // Disabled mode

  }

})

```

For performance reasons, store will move to disabled mode with 1 second delay

after last listener unsubscribing.

Call `keepMount()` to test store’s lazy initializer in tests and `cleanStores`

to unmount them after test.

```js

import { cleanStores, keepMount } from 'nanostores'

import { $profile } from './profile.js'

afterEach(() => {

  cleanStores($profile)

})

it('is anonymous from the beginning', () => {

  keepMount($profile)

  // Checks

})

```

### Computed Stores

Computed store is based on other store’s value.

```ts

import { computed } from 'nanostores'

import { $users } from './users.js'

export const $admins = computed($users, users => {

  // This callback will be called on every `users` changes

  return users.filter(user => user.isAdmin)

})

```

By default, `computed` stores update _each_ time any of their dependencies

gets updated. If you are fine with waiting until the end of a tick, you can

use `batched`. The only difference with `computed` is that it will wait until

the end of a tick to update itself.

```ts

import { batched } from 'nanostores'

const $sortBy = atom('id')

const $categoryId = atom('')

export const $link = batched([$sortBy, $categoryId], (sortBy, categoryId) => {

  return `/api/entities?sortBy=${sortBy}&categoryId=${categoryId}`

})

// `batched` will update only once even you changed two stores

export function resetFilters () {

  $sortBy.set('date')

  $categoryIdFilter.set('1')

}

```

Both `computed` and `batched` can be calculated from multiple stores:

```ts

import { $lastVisit } from './lastVisit.js'

import { $posts } from './posts.js'

export const $newPosts = computed([$lastVisit, $posts], (lastVisit, posts) => {

  return posts.filter(post => post.publishedAt > lastVisit)

})

```

### Actions

Action is a function that changes a store. It is a good place to move

business logic like validation or network operations.

Wrapping functions with `action()` can track who changed the store

in the [logger](https://github.com/nanostores/logger).

```ts

import { action } from 'nanostores'

export const increase = action($counter, 'increase', (store, add) => {

  if (validateMax(store.get() + add)) {

    store.set(store.get() + add)

  }

  return store.get()

})

increase(1) //=> 1

increase(5) //=> 6

```

All running async actions are tracked by `allTasks()`. It can simplify

tests with chains of actions.

```ts

import { allTasks } from 'nanostores'

renameAllPosts()

await allTasks()

```

### Tasks

`startTask()` and `task()` can be used to mark all async operations

during store initialization.

```ts

import { task } from 'nanostores'

onMount($post, () => {

  task(async () => {

    $post.set(await loadPost())

  })

})

```

You can wait for all ongoing tasks end in tests or SSR with `await allTasks()`.

```jsx

import { allTasks } from 'nanostores'

$post.listen(() => {}) // Move store to active mode to start data loading

await allTasks()

const html = ReactDOMServer.renderToString()

```

Async actions will be wrapped to `task()` automatically.

```ts

rename($post1, 'New title')

rename($post2, 'New title')

await allTasks()

```

### Store Events

Each store has a few events, which you listen:

* `onMount(store, cb)`: first listener was subscribed with debounce.

  We recommend to always use `onMount` instead of `onStart + onStop`,

  because it has a short delay to prevent flickering behavior.

* `onStart(store, cb)`: first listener was subscribed. Low-level method.

  It is better to use `onMount` for simple lazy stores.

* `onStop(store, cb)`: last listener was unsubscribed. Low-level method.

  It is better to use `onMount` for simple lazy stores.

* `onSet(store, cb)`: before applying any changes to the store.

* `onNotify(store, cb)`: before notifying store’s listeners about changes.

* `onAction(store, cb)`: start, end and errors of asynchronous actions.

`onSet` and `onNotify` events has `abort()` function to prevent changes

or notification.

```ts

import { onSet } from 'nanostores'

onSet($store, ({ newValue, abort }) => {

  if (!validate(newValue)) {

    abort()

  }

})

```

`onAction` event has two event handlers as properties inside:

* `onError` that catches uncaught errors during the execution of actions.

* `onEnd` after events has been resolved or rejected.

```ts

import { onAction } from 'nanostores'

onAction($store, ({ id, actionName, onError, onEnd }) => {

  console.log(`Action ${actionName} was started`)

  onError(({ error }) => {

    console.error(`Action ${actionName} was failed`, error)

  })

  onEnd(() => {

    console.log(`Action ${actionName} was stopped`)

  })

})

```

Event listeners can communicate with `payload.shared` object.

## Integration

### React & Preact

Use [`@nanostores/react`] or [`@nanostores/preact`] package

and `useStore()` hook to get store’s value and re-render component

on store’s changes.

```tsx

import { useStore } from '@nanostores/react' // or '@nanostores/preact'

import { $profile } from '../stores/profile.js'

export const Header = ({ postId }) => {

  const profile = useStore($profile)

  return Hi, {profile.name}

}

```

[`@nanostores/preact`]: https://github.com/nanostores/preact

[`@nanostores/react`]: https://github.com/nanostores/react

### Vue

Use [`@nanostores/vue`] and `useStore()` composable function

to get store’s value and re-render component on store’s changes.

```vue

import { useStore } from '@nanostores/vue'

import { $profile } from '../stores/profile.js'

const props = defineProps(['postId'])

const profile = useStore($profile)

  Hi, {{ profile.name }}

```

[`@nanostores/vue`]: https://github.com/nanostores/vue

### Svelte

Every store implements [Svelte's store contract]. Put `$` before store variable

to get store’s value and subscribe for store’s changes.

```svelte

  import { profile } from '../stores/profile.js'

Hi, {$profile.name}

```

In other frameworks, Nano Stores promote code style to use `$` prefixes

for store’s names. But in Svelte it has a special meaning, so we recommend

to not follow this code style here.

[Svelte's store contract]: https://svelte.dev/docs#component-format-script-4-prefix-stores-with-$-to-access-their-values-store-contract

### Solid

Use [`@nanostores/solid`] and `useStore()` composable function

to get store’s value and re-render component on store’s changes.

```js

import { useStore } from '@nanostores/solid'

import { $profile } from '../stores/profile.js'

export function Header({ postId }) {

  const profile = useStore($profile)

  return Hi, {profile().name}

}

```

[`@nanostores/solid`]: https://github.com/nanostores/solid

### Lit

Use [`@nanostores/lit`] and `StoreController` reactive controller

to get store’s value and re-render component on store’s changes.

```ts

import { StoreController } from '@nanostores/lit'

import { $profile } from '../stores/profile.js'

@customElement('my-header')

class MyElement extends LitElement {

  @property()

  private profileController = new StoreController(this, $profile)

  render() {

    return html\`Hi, ${profileController.value.name}`

  }

}

```

[`@nanostores/lit`]: https://github.com/nanostores/lit

### Angular

Use [`@nanostores/angular`] and `NanostoresService` with `useStore()`

method to get store’s value and subscribe for store’s changes.

```ts

// NgModule:

import { NANOSTORES, NanostoresService } from '@nanostores/angular';

@NgModule({

  providers: [{ provide: NANOSTORES, useClass: NanostoresService }]

})

```

```tsx

// Component:

import { Component } from '@angular/core'

import { NanostoresService } from '@nanostores/angular'

import { Observable, switchMap } from 'rxjs'

import { profile } from '../stores/profile'

import { IUser, User } from '../stores/user'

@Component({

  selector: "app-root",

  template: '
{{ user.name }}
'

})

export class AppComponent {

  currentUser$: Observable = this.nanostores.useStore(profile)

    .pipe(switchMap(userId => this.nanostores.useStore(User(userId))))


  constructor(private nanostores: NanostoresService) { }

}

```

[`@nanostores/angular`]: https://github.com/nanostores/angular

### Vanilla JS

`Store#subscribe()` calls callback immediately and subscribes to store changes.

It passes store’s value to callback.

```js

import { $profile } from '../stores/profile.js'

$profile.subscribe(profile => {

  console.log(`Hi, ${profile.name}`)

})

```

`Store#listen(cb)` in contrast calls only on next store change. It could be

useful for a multiple stores listeners.

```js

function render () {

  console.log(`${$post.get().title} for ${$profile.get().name}`)

}

$profile.listen(render)

$post.listen(render)

render()

```

See also `listenKeys(store, keys, cb)` to listen for specific keys changes

in the map.

### Server-Side Rendering

Nano Stores support SSR. Use standard strategies.

```js

if (isServer) {

  $settings.set(initialSettings)

  $router.open(renderingPageURL)

}

```

You can wait for async operations (for instance, data loading

via isomorphic `fetch()`) before rendering the page:

```jsx

import { allTasks } from 'nanostores'

$post.listen(() => {}) // Move store to active mode to start data loading

await allTasks()

const html = ReactDOMServer.renderToString()

```

### Tests

Adding an empty listener by `keepMount(store)` keeps the store

in active mode during the test. `cleanStores(store1, store2, …)` cleans

stores used in the test.

```ts

import { cleanStores, keepMount } from 'nanostores'

import { $profile } from './profile.js'

afterEach(() => {

  cleanStores($profile)

})

it('is anonymous from the beginning', () => {

  keepMount($profile)

  expect($profile.get()).toEqual({ name: 'anonymous' })

})

```

You can use `allTasks()` to wait all async operations in stores.

```ts

import { allTasks } from 'nanostores'

it('saves user', async () => {

  saveUser()

  await allTasks()

  expect(analyticsEvents.get()).toEqual(['user:save'])

})

```

## Best Practices

### Move Logic from Components to Stores

Stores are not only to keep values. You can use them to track time, to load data

from server.

```ts

import { atom, onMount } from 'nanostores'

export const $currentTime = atom(Date.now())

onMount($currentTime, () => {

  $currentTime.set(Date.now())

  const updating = setInterval(() => {

    $currentTime.set(Date.now())

  }, 1000)

  return () => {

    clearInterval(updating)

  }

})

```

Use derived stores to create chains of reactive computations.

```ts

import { computed } from 'nanostores'

import { $currentTime } from './currentTime.js'

const appStarted = Date.now()

export const $userInApp = computed($currentTime, currentTime => {

  return currentTime - appStarted

})

```

We recommend moving all logic, which is not highly related to UI, to the stores.

Let your stores track URL routing, validation, sending data to a server.

With application logic in the stores, it is much easier to write and run tests.

It is also easy to change your UI framework. For instance, add React Native

version of the application.

### Separate changes and reaction

Use a separated listener to react on new store’s value, not an action where you

change this store.

```diff

  const increase = action($counter, 'increase', store => {

    store.set(store.get() + 1)

-   printCounter(store.get())

  }

+ $counter.listen(counter => {

+   printCounter(counter)

+ })

```

An action is not the only way for store to a get new value.

For instance, persistent store could get the new value from another browser tab.

With this separation your UI will be ready to any source of store’s changes.

### Reduce `get()` usage outside of tests

`get()` returns current value and it is a good solution for tests.

But it is better to use `useStore()`, `$store`, or `Store#subscribe()` in UI

to subscribe to store changes and always render the actual data.

```diff

- const { userId } = $profile.get()

+ const { userId } = useStore($profile)

```

## Known Issues

### ESM

Nano Stores use ESM-only package. You need to use ES modules

in your application to import Nano Stores.

In Next.js ≥11.1 you can alternatively use the [`esmExternals`] config option.

For old Next.js you need to use [`next-transpile-modules`] to fix

lack of ESM support in Next.js.

[`next-transpile-modules`]: https://www.npmjs.com/package/next-transpile-modules

[`esmExternals`]: https://nextjs.org/blog/next-11-1#es-modules-support