FullStackOpen Part1-c 演習の気づき
useStateで配列を一定の長さで0で初期化
useState(Array(anecdotes.length).fill(0))
配列をsetStateで更新
const copy = […points]
copy[selected]++
setPoints(copy)
useState(Array(anecdotes.length).fill(0))
const copy = […points]
copy[selected]++
setPoints(copy)