如何使用写三元运算符在React.js中的点击事件

  • Z时代
  • 2024-01-10
  • 分类：问答

我在我的应用程序中使用了几个三元运算符，但我无法弄清楚如何在点击事件中使用三元运算符。如何使用写三元运算符在React.js中的点击事件

我在做的是一个弹出菜单。一旦该菜单项已被选择，其中一个菜单项将不可点击。只有另一个菜单项应该是可点击的。

图片

我尝试下面的代码，但没有奏效。我们不能在React中使用三元运算符来进行点击事件吗？

<p id="menuItem" {!this.sate.priceBar? onClick={this.clickHandle} : "" } style={!this.state.priceBar? { color:'white'} : {color : '#BBBBBB'} }>{!this.state.priceBar? "Spent Last 14 Days" : "Spent Last 14 Days"}</p>

完整代码

class Home extends React.Component{ 
constructor(props){ 
    super(props); 
    this.state = { 
     slideOpen : false, 
     priceBar: false, 
     open: false, 
    } 
this.handleClick = this.handleClick.bind(this); 
this.clickHandle = this.clickHandle.bind(this); 
} 
handleClick() { 
    this.setState({ 
     slideOpen : !this.state.slideOpen 
    }) 
console.log("slideOpen" + !this.state.slideOpen) 
} 
clickHandle() { 
this.setState({ 
      priceBar : !this.state.priceBar, 
      open: false 
    }) 
console.log(!this.state.priceBar) 
} 
handleTouchTap = (event) => { 
// This prevents ghost click. 
event.preventDefault(); 
this.setState({ 
    open: true, 
    anchorEl: event.currentTarget, 
}); 
}; 
handleRequestClose =() => { 
this.setState({ 
    open: false, 
}); 
}; 
render(){ 
    const PaymentPanel = this.state.slideOpen? "slideOpen" : ""; 
    const Dropdown = this.state.open? "show" : ""; 
return(
<div> 
<div id="PaymentPanel" className={PaymentPanel} > 
<div id="PaymentTitle" >{!this.state.priceBar? "Spent Last 14 Days" : "Spent Last 30 Days"}<img src={PaymentArrow} className="PaymentArrow PaymentToggle" onClick={this.handleTouchTap}/></div> 
<div id="Dropdown" className={Dropdown} open={this.state.open}> 
<p className="popoverToggle" onClick={this.handleRequestClose}> </p> 
<p id="menuItem" onClick={this.clickHandle} style={!this.state.priceBar? { color:'white'} : {color : '#BBBBBB'} }>{!this.state.priceBar? "Spent Last 14 Days" : "Spent Last 14 Days"}</p> 
<p id="menuItem" onClick={this.clickHandle} style={this.state.priceBar? { color:'white'} : {color : '#BBBBBB'} }>{this.state.priceBar? "Spent Last 30 Days" : "Spent Last 30 Days"}</p> 
</div> 
<h2 id="paymentSum" className={!this.state.open? "" : "close"}>{!this.state.priceBar? "$9,964.55" : "$19,929.1"}</h2> 
<ul className="paymentTool"> 
<li> 
<div onClick={this.handleTouchTap} className="tool">VISA <br /> {!this.state.priceBar? "$9,504.13" : "$19,008.26"}</div></li> 
<li><div className="tool">MasterCard <br /> {!this.state.priceBar? "$490.64" : "$981.28"}</div></li> 
<li><div className="tool">PayPal <br /> {!this.state.priceBar? "$824.52" : "$1,649.04"}</div></li> 
</ul> 
<div className="paymentSlide" onClick={this.handleClick}>{this.state.slideOpen? <img src={Arrowup} alt="arrowup" className="arrowup" /> : <img src={Arrowdown} alt="arrowdown" className="arrowdown"/>}</div> 
</div> 
<div className="PaymentTable" > 
<PaymentTable /> 
<ul> 
</ul> 
</div> 
</div> 
    ) 
} 
}

回答：

当然，三元操作不能用于返回DOM的属性，因为表达的返回值是一个字符串，浏览器和react.js引擎不会将字符串视为属性。

相反：

onClick={!this.state.priceBar ? this.clickHandle : ''}

修改代码：

handleTouchTap(event){ 
} 
handleRequestClose() { 
} 

class Home extends React.Component{  
constructor(props){  
    super(props);  
    this.state = {  
     slideOpen : false,  
     priceBar: false,  
     open: false,  
    }  
this.handleClick = this.handleClick.bind(this);  
this.clickHandle = this.clickHandle.bind(this);  
}  
handleClick() {  
    this.setState({  
     slideOpen : !this.state.slideOpen  
    })  
console.log("slideOpen" + !this.state.slideOpen)  
}  
clickHandle() {  
this.setState({  
      priceBar : !this.state.priceBar,  
      open: false  
    })  
console.log(!this.state.priceBar)  
}  
handleTouchTap (event) {  
// This prevents ghost click.  
event.preventDefault();  
this.setState({  
    open: true,  
    anchorEl: event.currentTarget,  
});  
}  
handleRequestClose() {  
this.setState({  
    open: false,  
});  
}  
render(){  
    const PaymentPanel = this.state.slideOpen? "slideOpen" : "";  
    const Dropdown = this.state.open? "show" : "";  
return( 
<div>  
<div id="PaymentPanel" className={PaymentPanel} >  
<div id="PaymentTitle" >{!this.state.priceBar? "Spent Last 14 Days" : "Spent Last 30 Days"}</div>  
<p id="menuItem" onClick={this.clickHandle} style={!this.state.priceBar? { color:'white'} : {color : '#BBBBBB'} }>{!this.state.priceBar? "Spent Last 14 Days" : "Spent Last 14 Days"} (Click me!)</p>  
click top line  
</div>  
</div>  
    )  
}  
}  
ReactDOM.render(<Home />, document.querySelector('.app'))

<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react.min.js"></script>  
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react-dom.min.js"></script>  
<div class="app"></div>

回答：

<p id="menuItem" onClick={!this.state.priceBar ? this.clickHandle : null}>

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