React Hooks

useReducer.js

import { createRef, useState, useEffect, useContext } from 'react'

export function useReducer(reducer, initialArg, init) {  
  const [stateRef] = useState(() => {
    if (init === undefined) {
      return createRef(initialArg)
    } else {
      return createRef(init(initialArg)))
    }
  })
  const dispatch = useCallback((action) => {
    stateRef.current = reducer(stateRef.current, action)
  }, [stateRef, reducer])
  
  return [stateRef.current, dispatch]
}

export function useCallback(fn, deps) {
  return useMemo(() => fn, deps)
}

export function useMemo(create, deps) {
  const [value, setValue] = useState(create)
  useEffect(() => {
    setValue(create())
  }, deps)
  return value
}

export function useRef(initialValue) {
  const [ref] = useState(() => createRef(initialValue))
  return ref
}

export function useImperativeHandle(ref, createHandler, deps) {
  
}