React之js實現跳轉路由

1、新增知識

/*
實現js跳轉路由：https://reacttraining.com/react-router/web/example/auth-workflow
1、要引入Redirect
    import {BrowserRouter as Router,Route,Link,Redirect,withRouter} from "react-router-dom";

2、定義一個flag
        this.state = { 
              loginFlag:false            
        };

3、render里面判斷flag 來決定是否跳轉
        if(this.state.loginFlag){
            return <Redirect to={{ pathname: "/" }} />;
        }

4、要執行js跳轉
        通過js改變loginFlag的狀態
        改變以后從新render 就可以通過Redirect自己來跳轉
*/

2、代碼實現js跳轉路由

import React, { Component } from 'react';
import {Redirect} from "react-router-dom";
class Login extends Component {
    constructor(props) {
        super(props);
        this.state = { 
            loginFlag:false            
        };
    }

    doLogin=(e)=>{
        e.preventDefault();
        let username=this.refs.username.value;
        let password=this.refs.password.value;
        console.log(username,password)
        if(username=='admin' && password=='123456'){
            //登錄成功   跳轉到首頁
            this.setState({
                loginFlag:true
            })
        }else{
            alert('登錄失敗')
        }
    }

    render() {
        if(this.state.loginFlag){
            // return <Redirect to={{ pathname: "/" }} />;
            return <Redirect to='/' />;
        }
        return (    
            <div>
                 <br /> <br /> <br />
                <form onSubmit={this.doLogin}>
                        <input type="text"  ref="username" />  <br /> <br />
                        <input type="password"  ref="password" /> <br /> <br />
                         <input type="submit"  value="執行登錄"/>
                </form>
            </div> 
        );
    }
}
export default Login;

3、