分割代入を利用したstate[ ]の更新 - Qiita

const [state, setState] = useState({id:1, firstName:"taro", lastName:"sato"}); const obj = {firstName:"hanako", lastName:"sato"}; const pushFunction = (state) => { setState( [...state, {id:2, ...obj}] ) } // ...state => {id:1, firstName:"taro", lastName:"sato"} // ...arr => firstName:"hanako", lastName:"sato" // id:2, ...arr => id:2, firstName:"hanako", lastName:"sato" // [...state, {id:2, ...obj}