React:Conditional Rendering(条件渲染) 就像JS中常常会根据条件(比如if/else、switch)返回不同的值,React中也可以根据组件的状态或其他参考条件返回不同的React Element。 比如根据用户是否登陆渲染对应的UI面板。 1class LoginControl extends React.Component {2constructor(props) {3super(props);4this.handleLoginCli...
if (renderComponent1) { component = <Component1 />; } return component; } 三元运算符 三元运算符的语法如下: condition ? expr_if_true : expr_if_false 用在JSX 上也很方便: function render() { return renderComponent1 ? <Component1 /> : null; } 但三元运算符产生嵌套时,理解成本会变得很高。
importReact, {Component}from"react";importReactDOMfrom"react-dom";import"./styles.css";classAppextendsComponent{constructor(props) {super(props);this.state= {isLoggedIn:true}; }render() {return(This is a Demo showing several ways to implement Conditional Rendering in React.LoginLogout); } }...
在React中,你还可以利用render函数将子组件传递给其他组件。这时通常使用特殊的props,如children或自定义的prop来实现。 class ParentComponent extends React.Component { render() { return ( <Sidebar> <Navigation /> </Sidebar> ); } } class Sidebar extends React.Component { render() { const { children...
{this.state.showWarning ? 'Hide' : 'Show'} ); } } ReactDOM.render( <Page />, document.getElementById('root') ); [在线尝试]() 组件的render方法返回null不影响触发组件的声明周期方法。例如componentDidUpdate仍然会被调用。
render(<Goal isGoal={true} />); Run Example » Logical && OperatorAnother way to conditionally render a React component is by using the && operator.Example: We can embed JavaScript expressions in JSX by using curly braces: function Garage(props) { const cars = props.cars; return ( <...
class App extends Component { constructor(props) { super(props); this.state = { isLoggedIn: true }; } render() { return ( This is a Demo showing several ways to implement Conditional Rendering in React. Login Logout ); } } const...
function ConditionalComponent({ shouldRender }) { return shouldRender && This component is rendered conditionally.; } 使用条件语句 代码语言:txt 复制 function ConditionalComponent({ condition }) { let content; if (condition) { content = Condition is true.; } else { content = Condition is false....
React conditional rendering 1. DEMO#1 * Greeting.js import React from 'react'; class Greeting extends React.Component { constructor(props) { super(props) } render() { const isLoggedIn = this.props.isLoggedIn; if (isLoggedIn) { return <UserGreeting />...
class App extends React.Component { state = { isLoggedIn: false }; handleLogin = () => { this.setState({ isLoggedIn: true }); }; render() { return ( {this.state.isLoggedIn ? <UserProfile /> : <LoginPrompt />} Login ); } } 3. 组件未正确导入 确保你已经正确导入了需要渲...