router

1. Route参数

       <Route
           path='/'
           exact={true}
           component={Home}
       >
       </Route>
   
       <Route
           path='/about'
           render={props => <About {...props} />}
       >
       </Route>
   
       <Route
           path='/dashboard1'
           children={Dashboard}
       >
       </Route>
   
       <Route
           path='/dashboard2'
           children={(props) => <Dashboard {...props} />}
       >
       </Route>
   
       component 可以是类组件 不能是组件实例; 也可以是函数组件
       render渲染的组件,可以是函数组件, 不能是类组件, 在切换路由之后会卸载, 而children渲染的组件不会卸载, 只会调用一次
       children 不管路径是否匹配都会渲染 只能是函数组件 通过props.match可以判断当前组件是否是匹配的
   

2. router相关

       import {
           BrowserRouter,
           Route,
           NavLink,
           Switch,
           withRouter,
           Redirect
       } from 'react-router-dom'
   
       // 给组件添加路由信息
       @withRouter
       class MyNavLink extends Component {
           render() {
               const pathname = this.props.location.pathname;
               this.props.history.push('/home');
   
               return <div>
   
               </div>
           }
       }
   
       const Home = withRouter((props) => <div>Home</div>);
   
       render() {
           return <>
               <Route path="/home">
                   <Home></Home>
               </Route>
               <Redirect from='/' to='/home' />    
           </>
       }
       ```
   
   

3. Redirect & 传参

       function loginPage() {
           const { state: { from } } = useLocation();
           const history = useHistory();
   
           function login() {
               // history.push(from);
               history.replace(from);
           }
   
           return <div>
               页面来自于: {from}
           </div>  
       }
   
       const PrivateRoute = ({ children, ...rest }) => {
           const { pathname } = useLocation();
   
           return (
               <Route {...rest}>
                   {isAuth ? children : <Redirect to={{  path: '/login', state: { from: pathname } }}>}
               </Route>
           )
       }
       ```
   
   

4. 取参数

       // /about/:id
       // <NavLink to="/about/123"></NavLink>
       // <NavLink to={{ pathname: '/about', state: { id: 12 } }}></NavLink>
       // <NavLink to={{ pathname: '/about?sw=345', state: { id: 12 } }}></NavLink>
   
       const About = function() {
           const { id } = useParams();
           const { state: { id }, search } = useLocation();
           const query = new URLSearchParams(search);
           const sw = query.get('sw');
           return <>
               Params { id }
           </>
       }
       ```
   
   

5. Page 404

       const Page404 = () => {
           return <>
               404 
           </>
       }
   
       <Route path="*">
           <Page404 />
       </Route>
       ```
   
   

6. Route Config

       <Switch>
           {routes.map((item, index) => (
               <Route
                   key={index}
                   path={route.path}
                   exact={route.exact}
                   children={<route.main />}
               >
               </Route>
           ))}
       </Switch>
       ```
   
   

7. Children Config

       const routes = [
           { 
               path: '/a',
               component: Home
           },
           { 
               path: '/b',
               component: About,
               children: [
                   {
                       path: '/b1',
                       component: About1,
                   },
                   {
                       path: '/b2',
                       component: About2,
                   }
               ]
           },
       ]
   
       <div>
           {route.map((item,index) => {
               let { path } = item;
               return (
                   <Route
                       key={path}
                       path={path}
                   >
                       <RouteWithSubRoutes {...props} route={item}></RouteWithSubRoutes>
                   </RouteW>
               )
           }}
       </div>
   
       function About(props) {
           const { routes } = props;
           return <>
               <Switch>
                   {routes.map(item => (
                       <Route
                           key={item.path}
                           path={item.path}
                       >
                           <RouteWithSubRoutes {...props } key={item.path} route={item} >
                       </Route>
                   ))}
               </Switch>
           </>
       }
   
       function RouteWithSubRoutes(props) {
           const { route } = props
           return (
               <route.component
                   {...props}
                   routes={route.children}
               >
               </route.component>
           )
       }
       ```