lovecoding
/
w1020


			
				
					
						
						
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							<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="./babel.min.js"></script>
    <script src="./react.development.js"></script>
    <script src="./react-dom.development.js"></script>
</head>

<body>
    <div id="root"></div>
    <script type="text/babel">
        const root = ReactDOM.createRoot(document.getElementById("root"));
        /**
         * 条件判断：
         * if/else/else-if
         * switch-case
         * 三元判断
        */
        function App() {
            return (
                <div>
                    <News />
                </div>
            )
        }
        class News extends React.Component {
            constructor() {
                super();
                this.state = {
                    msg: {
                        user: "图图",
                        age: 3
                    },
                    token: JSON.parse(localStorage.getItem("token"))
                }
            }
            handleLogin() {
                localStorage.setItem('token',JSON.stringify('haha'));
                this.setState({
                    token:'haha'
                })
            }
            render() {
                let { token, msg } = this.state;
                console.log(token, msg)
                // 逻辑： 如果存在 token 显示已登录； 不存在 显示 请登录
                // if (token) {
                //     return (
                //         <div>
                //             已登录
                //         </div>
                //     )
                // } else {
                //     return (
                //         <div>
                //             请登录
                //         </div>
                //     )
                // }
                return token ? (
                    <h1>已登录</h1>
                ) : (
                    <div>
                        <h2>请登录</h2>
                        <button onClick={this.handleLogin.bind(this)}>请登录</button>    
                    </div>
                )
            }
        }
        root.render(<App />);
    </script>
</body>

</html>