如何在单击时从另一个同级组件中增加一个值？

Question

function LeagueBadge(props) {
    return (
        <img src={props.badgeUrl} alt="missing alt text" />
    );
}

class LeagueInfo extends Component {
    constructor(props) {
        super(props);
        this.state = {
            amountOfPlayers: null,
            rpPerSecond: null,
            rpCost: null,
        };
    }
    render() {
        return (
            <div>
                <h4>{this.props.name} players: {this.props.amountOfPlayers}</h4>
                <h4>RP per second: {this.props.rpPerSecond}</h4>
                <h4>RP cost: {this.props.rpCost}</h4>
            </div>
        );
    }
}

class League extends Component {
    render() {
        return (
            <div>
                <LeagueBadge badgeUrl={this.props.badge} />
                <LeagueInfo name={this.props.name} />
            </div>
        );
    }
}

class App extends Component {
    render() {
        return (
            <div className="App">
                <h1>Players</h1>
                <League name="Bronze" badge={ require('./bronze.png') }></League>
                <League name="Silver" badge={ require('./silver.png') }></League>
                <League name="Gold" badge={ require('./gold.png') }></League>
                <League name="Platinum" badge={ require('./platinum.png') }></League>
                <League name="Diamond" badge={ require('./diamond.png') }></League>
                <League name="Master" badge={ require('./master.png') }></League>
                <League name="Challenger" badge={ require('./challenger.png') }></League>
            </div>
        );
    }
}

我希望能够单击作为 LeagueBadge 组件的图像并增加其兄弟 LeagueInfo 中 amountOfPlayers 的值。我已经用谷歌搜索了 react siblings communication，只找到了带有 input 标签和 onChange 的例子，但在这里我想要 img 标签或按钮和 onClick。

Answer 1

您可以将 amountOfPlayers 的状态提升到 <Leauge /> 组件中，以便： - 可以从 <LeagueBadge /> 触发更新 - 而且，该状态可以传递给您的 <LeagueInfo /> 组件

这将允许您根据需要在 <LeagueInfo /> 和 <LeagueBadge /> 兄弟姐妹之间共享和同步状态。

为此，您需要向 <LeagueBadge /> 添加一个 onClick 回调，当 img 元素被点击时触发。在 <Leauge /> 渲染方法中，您可以提供在 <Leauge /> 中递增 amountOfPlayers 状态的逻辑。当 amountOfPlayers 递增并调用 setState 时（在 <Leauge /> 中），这反过来会导致您的 <Leauge /> 组件重新呈现自身（并且 children/siblings).因为 amountOfPlayers 的更新值作为 prop 传递给 <LeagueInfo /> 组件，所以这个更新值将在 <LeagueInfo /> 中呈现 - 有效地实现你所追求的。

类似这样的东西可能对你有用：

class LeagueBadge extends Component {
    render() {

    // Add props.onClick callback to trigger click event in <League /> 
    // component
    return (
        <img src={this.props.badgeUrl} alt="missing alt text" 
             onClick={() => this.props.onClick()} />
    );
    }
}

class LeagueInfo extends Component {
    constructor(props) {
        super(props);
        this.state = {
            // amountOfPlayers: null, // This is not needed, as it's supplied by props
            rpPerSecond: null,
            rpCost: null,
        };
    }
    render() {
        return (
            <div>
                <h4>{this.props.name} players: {this.props.amountOfPlayers}</h4>
                <h4>RP per second: {this.props.rpPerSecond}</h4>
                <h4>RP cost: {this.props.rpCost}</h4>
            </div>
        );
    }
}

class League extends Component {

    componentWillMount() {

        this.setState({
            amountOfPlayers : 0
        })
    }

    render() {

        // Locally defined function that increments amountOfPlayers and
        // updates state
        const incrementAmountOfPlayers  = () => {
            this.setState({ amountOfPlayers : 
            this.state.amountOfPlayers + 1 })
        }

        return (
            <div>
                <LeagueBadge badgeUrl={this.props.badge} 
                             onClick={ () => incrementAmountOfPlayers() } />
                <LeagueInfo name={this.props.name} amountOfPlayers={ this.state.amountOfPlayers } />
            </div>
        );
    }
}

Answer 2

将您的状态保留在联赛组件中，并传递负责将其更改为 LeagueBadge 的函数，例如：

class League extends Component {
    constructor(props) {
        super(props);
        this.state = {
            amountOfPlayers: null,
        };
    }
    handleClick = () => {
    this.setState(prevState => {
       return {amountOfPlayers: prevState.amountOfPlayers + 1}
    })
  }
    render() {
        return (
            <div>
                <LeagueBadge badgeUrl={this.props.badge} incrementPlayers={this.handleClick}/>
                <LeagueInfo name={this.props.name} amountOfPlayers={this.state.amountOfPlayers}/>
            </div>
        );
    }
}


function LeagueBadge(props) {
    return (
        <img src={props.badgeUrl} alt="missing alt text" onClick={this.props.incrementPlayers}/>
    );
}

在您的信息组件中使用 this.props.amountOfPlayers。

如何在单击时从另一个同级组件中增加一个值？

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