react列表中，当key改变后发生的事情

Main.jsx

export default class Main extends PureComponent {
    constructor(props) {
        super(props);
        this.state = {
            list: [
                {
                    key: ,
                    value:
                },
                {
                    key: ,
                    value:
                },
                {
                    key: ,
                    value:
                }
            ]
        }
        this.setKey = ::this.setKey;
    }    componentWillMount() {
        console.log('main will mount');
    }    componentDidMount() {
        console.log('main did mount');
    }    componentWillUpdate() {
        console.log('main will update');
    }    componentDidUpdate() {
        console.log('main did update');
    }    componentWillUnmount() {
        console.log('main will unmount');
    }    setKey() {
        const { list } = this.state;        this.setState({
            list: Array.from(list, item => {
                return Object.assign(item, {
                    key: item.key +
                });
            })
        });
    }    render() {
        const { list } = this.state;
        return (
            <div>
                {list.map(item => <List key={item.key} value={item.value} />)}
                <button onClick={this.setKey}>key</button>
            </div>
        )
    }
}        

List.jsx

export default class List extends PureComponent {
    constructor(props) {
        super(props);
    }    componentWillMount() {
        console.log(`list${this.props.value} will mount`);
    }    componentDidMount() {
        console.log(`list${this.props.value} did mount`);
    }    componentWillUpdate() {
        console.log(`list${this.props.value} will update`);
    }    componentDidUpdate() {
        console.log(`list${this.props.value} did update`);
    }    componentWillUnmount() {
        console.log(`list${this.props.value} will unmount`);
    }    render() {
        const { value } = this.props;
        return(
            <div>
                list{value}
            </div>
        )
    }
}

当点击key按钮后会发生什么呢？先分析一下