Immer

Install

You have to install immer and jotai-immer to use this feature.

npm install immer jotai-immer

atomWithImmer

atomWithImmer creates a new atom similar to the regular atom with a different writeFunction. In this bundle, we don't have read-only atoms, because the point of these functions is the immer produce(mutability) function. The signature of writeFunction is (get, set, update: (draft: Draft<Value>) => void) => void.

import { useAtom } from 'jotai'
import { atomWithImmer } from 'jotai-immer'

const countAtom = atomWithImmer({ value: 0 })

const Counter = () => {
  const [count] = useAtom(countAtom)
  return <div>count: {count.value}</div>
}

const Controls = () => {
  const [, setCount] = useAtom(countAtom)
  // setCount === update : (draft: Draft<Value>) => void
  const inc = () =>
    setCount((draft) => {
      ++draft.value
    })
  return <button onClick={inc}>+1</button>
}

Examples

Check this example with atomWithImmer:

withImmer

withImmer takes an atom and returns a derived atom, same as atomWithImmer it has a different writeFunction.

import { useAtom, atom } from 'jotai'
import { withImmer } from 'jotai-immer'

const primitiveAtom = atom({ value: 0 })
const countAtom = withImmer(primitiveAtom)

const Counter = () => {
  const [count] = useAtom(countAtom)
  return <div>count: {count.value}</div>
}

const Controls = () => {
  const [, setCount] = useAtom(countAtom)
  // setCount === update : (draft: Draft<Value>) => void
  const inc = () =>
    setCount((draft) => {
      ++draft.value
    })
  return <button onClick={inc}>+1</button>
}

Examples

Check this example with withImmer:

useImmerAtom

This hook takes an atom and replaces the atom's writeFunction with the new immer-like writeFunction like the previous helpers.

import { atom } from 'jotai'
import { useImmerAtom } from 'jotai-immer'

const primitiveAtom = atom({ value: 0 })

const Counter = () => {
  const [count] = useImmerAtom(primitiveAtom)
  return <div>count: {count.value}</div>
}

const Controls = () => {
  const [, setCount] = useImmerAtom(primitiveAtom)
  // setCount === update : (draft: Draft<Value>) => void
  const inc = () =>
    setCount((draft) => {
      ++draft.value
    })
  return <button onClick={inc}>+1</button>
}

It would be better if you don't use withImmer and atomWithImmer with useImmerAtom because they provide the immer-like writeFunction and we don't need to create a new one.

You can use useSetImmerAtom if you need only the setter part of useImmerAtom.

Examples

Check this example with useImmerAtom:

Demo