Skip to content
forked from pmndrs/jotai

πŸ‘» Primitive and flexible state management for React

License

Notifications You must be signed in to change notification settings

noteverseio/jotai

This branch is 243 commits behind pmndrs/jotai:main.

Folders and files

NameName
Last commit message
Last commit date

Latest commit

c974d15 Β· Mar 4, 2024
May 6, 2023
Feb 28, 2024
Feb 12, 2024
Jan 1, 2024
Feb 28, 2024
Nov 14, 2023
Jun 22, 2022
Feb 28, 2024
Feb 28, 2024
Mar 4, 2024
Jul 31, 2023
Nov 10, 2021
Aug 21, 2023
Jan 1, 2023
Jul 18, 2021
Feb 28, 2024
Dec 26, 2023
Feb 28, 2024
Feb 21, 2024
Feb 23, 2024
Feb 28, 2024

Repository files navigation


Jotai (light mode) Jotai (dark mode)


visit jotai.org or npm i jotai

Build Status Build Size Version Downloads Discord Shield Open Collective

Jotai scales from a simple useState replacement to an enterprise TypeScript application.

  • Minimal core API (2kb)
  • Many utilities and extensions
  • No string keys (compared to Recoil)

Examples: Demo 1 | Demo 2

First, create a primitive atom

An atom represents a piece of state. All you need is to specify an initial value, which can be primitive values like strings and numbers, objects, and arrays. You can create as many primitive atoms as you want.

import { atom } from 'jotai'

const countAtom = atom(0)
const countryAtom = atom('Japan')
const citiesAtom = atom(['Tokyo', 'Kyoto', 'Osaka'])
const mangaAtom = atom({ 'Dragon Ball': 1984, 'One Piece': 1997, Naruto: 1999 })

Use the atom in your components

It can be used like React.useState:

import { useAtom } from 'jotai'

function Counter() {
  const [count, setCount] = useAtom(countAtom)
  return (
    <h1>
      {count}
      <button onClick={() => setCount((c) => c + 1)}>one up</button>
      ...

Create derived atoms with computed values

A new read-only atom can be created from existing atoms by passing a read function as the first argument. get allows you to fetch the contextual value of any atom.

const doubledCountAtom = atom((get) => get(countAtom) * 2)

function DoubleCounter() {
  const [doubledCount] = useAtom(doubledCountAtom)
  return <h2>{doubledCount}</h2>
}

Creating an atom from multiple atoms

You can combine multiple atoms to create a derived atom.

const count1 = atom(1)
const count2 = atom(2)
const count3 = atom(3)

const sum = atom((get) => get(count1) + get(count2) + get(count3))

Or if you like fp patterns ...

const atoms = [count1, count2, count3, ...otherAtoms]
const sum = atom((get) => atoms.map(get).reduce((acc, count) => acc + count))

Derived async atoms needs suspense

You can make the read function an async function too.

const urlAtom = atom('https://json.host.com')
const fetchUrlAtom = atom(async (get) => {
  const response = await fetch(get(urlAtom))
  return await response.json()
})

function Status() {
  // Re-renders the component after urlAtom is changed and the async function above concludes
  const [json] = useAtom(fetchUrlAtom)
  ...

You can create a writable derived atom

Specify a write function at the second argument. get will return the current value of an atom. set will update the value of an atom.

const decrementCountAtom = atom(
  (get) => get(countAtom),
  (get, set, _arg) => set(countAtom, get(countAtom) - 1)
)

function Counter() {
  const [count, decrement] = useAtom(decrementCountAtom)
  return (
    <h1>
      {count}
      <button onClick={decrement}>Decrease</button>
      ...

Write only derived atoms

Just do not define a read function.

const multiplyCountAtom = atom(null, (get, set, by) =>
  set(countAtom, get(countAtom) * by),
)

function Controls() {
  const [, multiply] = useAtom(multiplyCountAtom)
  return <button onClick={() => multiply(3)}>triple</button>
}

Async actions

Just make the write function an async function and call set when you're ready.

const fetchCountAtom = atom(
  (get) => get(countAtom),
  async (_get, set, url) => {
    const response = await fetch(url)
    set(countAtom, (await response.json()).count)
  }
)

function Controls() {
  const [count, compute] = useAtom(fetchCountAtom)
  return (
    <button onClick={() => compute('http://count.host.com')}>compute</button>
    ...

Links

About

πŸ‘» Primitive and flexible state management for React

Resources

License

Stars

Watchers

Forks

Releases

No releases published

Packages

No packages published

Languages

  • TypeScript 80.4%
  • JavaScript 18.2%
  • CSS 1.4%