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posted at

updated at

ReactのsetStateで配列の一部を変更する

備忘録

Reactの勉強をはじめて2時間詰まったところ↓
reactのstateに配列を設定した時、インデックスを利用して一部を変更したい。

解決策

スライスで配列をコピーしてからコピーの中身を変更して、それをsetStateする

constructor(props) {
        super(props);
        this.state = {
            humans: ["", "", ""]
        }
    }

    change(i) {
        const humans_copy = this.state.humans.slice();
        humans_copy[i] = "変更"
        this.setState({humans: humans_copy})
    }
}

結局チュートリアルでした。

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26
Help us understand the problem. What are the problem?