我正在尝试在 react 中使用带映射循环渲染的条件,但我收到错误。
代码如下:
const navbarValue = [{"Category":"Home","Status":1},{"Category":"About","Status":0},{"Category":"Contact","Status":0}];
function NavbarActive(props) {
return (
<li className="active"><a href="">{props.Category}</a></li>
);
};
function NavbarNotActive(props) {
return (
<li><a href="">{props.Category}</a></li>
);
};
function NavbarList(props) {
return (
<div className="navbar-wrapper">
<div className="container">
<nav className="navbar navbar-fixed-static-top navbar-inverse">
<div className="container">
<div className="navbar-header">
<button type="button" className="navbar-toggle collapsed" data-toggle="collapse" data-target="#navbar" aria-expanded="false" aria-controls="navbar">
<span className="sr-only">Toggle navigation</span>
<span className="icon-bar"></span>
<span className="icon-bar"></span>
<span className="icon-bar"></span>
</button>
<a className="navbar-brand" href="#">Brand</a>
</div>
<div id="navbar" className="collapse navbar-collapse">
<ul className="nav navbar-nav">
{navbarValue.map((obj, index) =>
if (obj.Status) {
<NavbarActive key={index} Category ={obj.Category }/>
}
<NavbarNotActive key={index} Category ={obj.Category }/>
)}
</ul>
</div>
</div>
</nav>
</div>
</div>
);
};
ReactDOM.render(
<NavbarList />,
document.getElementById('root')
);
<link href="https://netdna.bootstrapcdn.com/bootstrap/3.0.0/css/bootstrap.min.css" rel="stylesheet"/>
<script src="https://netdna.bootstrapcdn.com/bootstrap/3.0.0/js/bootstrap.min.js"></script>
<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>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id="root"></div>
没有条件语句的工作代码:
const navbarValue = [{"Category":"Home","Status":1},{"Category":"About","Status":0},{"Category":"Contact","Status":0}];
function NavbarActive(props) {
return (
<li className="active"><a href="">{props.Category}</a></li>
);
};
function NavbarNotActive(props) {
return (
<li><a href="">{props.Category}</a></li>
);
};
function NavbarList(props) {
return (
<div className="navbar-wrapper">
<div className="container">
<nav className="navbar navbar-fixed-static-top navbar-inverse">
<div className="container">
<div className="navbar-header">
<button type="button" className="navbar-toggle collapsed" data-toggle="collapse" data-target="#navbar" aria-expanded="false" aria-controls="navbar">
<span className="sr-only">Toggle navigation</span>
<span className="icon-bar"></span>
<span className="icon-bar"></span>
<span className="icon-bar"></span>
</button>
<a className="navbar-brand" href="#">Brand</a>
</div>
<div id="navbar" className="collapse navbar-collapse">
<ul className="nav navbar-nav">
{navbarValue.map((obj, index) =>
<NavbarNotActive key={index} Category ={obj.Category }/>
)}
</ul>
</div>
</div>
</nav>
</div>
</div>
);
};
ReactDOM.render(
<NavbarList />,
document.getElementById('root')
);
<script src="https://netdna.bootstrapcdn.com/bootstrap/3.0.0/js/bootstrap.min.js"></script>
<link href="https://netdna.bootstrapcdn.com/bootstrap/3.0.0/css/bootstrap.min.css" rel="stylesheet"/>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<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 id="root"></div>
我使用 obj.Status 作为“True”或“False”来指示节点是否必须呈现为事件状态或非事件状态。
最佳答案
首先需要使用{}
,然后在map body中放入if-else
语句,并返回结果。
这样写:
{navbarValue.map((obj, index) => {
if (obj.Status)
return <NavbarActive key={index} Category ={obj.Category }/>
return <NavbarNotActive key={index} Category ={obj.Category }/>
})}
或者使用ternary operator :
{navbarValue.map((obj, index) => obj.Status ?
<NavbarActive key={index} Category ={obj.Category }/>
:
<NavbarNotActive key={index} Category ={obj.Category }/>}
)}
关于javascript - 条件渲染在 React 映射循环中不起作用,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/45128066/