useMemo vs. useState

useGreetings.js

function useGreetings(language) {
  const [greetings, setGreetings] = useState()
  
  // 1. language changes (render)
  // 2. useEffect triggers (post-render)
  // 3. greetings are updated (render)
  useEffect(() => {
    switch (language) {
      case "fr": {
        setGreetings(["salut", "bonjour"])

        break
      }
    }
  }, [language])

  // 1. language changes (render)
  // 2. useMemo triggers (same render)
  const memoizedGreetings = useMemo(() => {
    switch (language) {
      case "fr": {
        return ["salut", "bonjour"]
      }
    }
  }, [language])
  
  return memoizedGreetings
}