Setup

Reatom is a framework-agnostic state manager, and you can use it with various adapters for different frameworks. This guide provides a common usage with React.js, as it is the most commonly used view library currently.

Create new project from template

The base template project includes Vite, TypeScript, React and Reatom ecosystem: https://github.com/artalar/reatom-react-ts

You could try it online: codesandbox, stackblitz, gitpod

To setup it in your machine you can use degit package.

npx degit github:artalar/reatom-react-ts PROJECT-NAME
cd PROJECT-NAME

npm install
npm run dev

Add to existing project

npm i @reatom/core

With React

Installation

npm i @reatom/npm-react

You need to set up the main context and put it into the provider at the top of your application.

import { createCtx } from '@reatom/core'
import { reatomContext } from '@reatom/npm-react'
import { Main } from './path/to/an/Main'

const ctx = createCtx()

export const App = () => (
  <reatomContext.Provider value={ctx}>
    <Main />
  </reatomContext.Provider>
)

Usage

The useAtom function allows you to have an experience similar to useState, but with shared atom state.

const nameAtom = atom('Joe')
const greetingAtom = atom((ctx) => `Hello, ${ctx.spy(nameAtom)}!`)

const Greeting = () => {
  const [name, setName] = useAtom(nameAtom)
  const [greeting] = useAtom(greetingAtom)

  return (
    <br>
      What is your name?:
      <input value={name} onChange={(e) => setName(e.currentTarget.value)} />
      </br>
      <h1>Hello {greeting}!</h1>
    </>
  )
}

Also, you can create computed atoms (kind of selectors) right inside useAtom.

const nameAtom = atom('Joe')

const Greeting = () => {
  const t = useTranslation()
  const [name, setName] = useAtom(nameAtom)
  const [greeting] = useAtom((ctx) => `${t('common:GREETING')} ${ctx.spy(nameAtom)}!`, [t])

  return (
    <br>
      What is your name?:
      <input value={name} onChange={(e) => setName(e.currentTarget.value)} />
      </br>
      <h1>{greeting}!</h1>
    </>
  )
}

This is very basic functionality of reatom-react bindings, see more in @reatom/npm-react package documentation