1. Advanced
  2. Component State

Component State

To isolate component state for reusability, Valtio must live in the React lifecycle. You can wrap a proxy in a ref, passing it with props or context.

import { createContext, useContext } from 'react'
import { proxy, useSnapshot } from 'valtio'

const MyContext = createContext()

const MyProvider = ({ children }) => {
  const state = useRef(proxy({ count: 0 })).current
  return <MyContext.Provider value={state}>{children}</MyContext.Provider>
}

const MyCounter = () => {
  const state = useContext(MyContext)
  const snap = useSnapshot(state)
  return (
    <>
      {snap.count} <button onClick={() => ++state.count}>+1</button>
    </>
  )
}

If you are not happy with useRef usage, consider use-constant instead. You may also create custom hooks wrapping useContext and optionally useSnapshot.

Codesandbox example