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分割代入を利用したstate[ ]の更新

JavaScript
React

Posted at 2021-09-12

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}] => [{id:1, firstName:"taro", lastName:"sato"}, {id:2, firstName:"hanako", lastName:"sato"}]

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