Molecules

Jotai atoms provide a basic solution to optimize re-renders. Atoms defined globally can depend on other atoms, but they can't depend on props and state within a component tree. It's possible to define atoms within a component tree, but then you would need to pass those atoms in some ways (for example, atoms-in-atom.)

jotai-molecules is a third-party library to help such use cases.

See Motivation for more details.

Install

yarn add jotai-molecules

Counter Example

import { atom, useAtom } from 'jotai'
import {
  molecule,
  useMolecule,
  createScope,
  ScopeProvider,
} from 'jotai-molecules'

const InitialCountScope = createScope(0)
const countMolecule = molecule((getMol, getScope) => {
  const initialCont = getScope(InitialCountScope)
  return atom(initialCont)
})

const Counter = () => {
  const countAtom = useMolecule(countMolecule)
  const [count, setCount] = useAtom(countAtom)
  return (
    <div>
      {count} <button onClick={() => setCount((c) => c + 1)}>+1</button>
    </div>
  )
}

const App = () => (
  <div>
    <h1>With initial value 1</h1>
    <ScopeProvider scope={InitialCountScope} value={1}>
      <Counter />
      <Counter />
    </ScopeProvider>
    <h1>With initial value 2</h1>
    <ScopeProvider scope={InitialCountScope} value={2}>
      <Counter />
      <Counter />
    </ScopeProvider>
    <h1>Default</h1>
    <Counter />
    <Counter />
  </div>
)