反应路由器切换行为 [英] React router Switch behavior

问题描述

(react-router-dom 版本:4.1.1)

我已经设置了工作路线，但我对为什么需要 感到有些困惑:

index.js

从'react'导入React；从react-router-dom"导入 { HashRouter, Route, Switch };从'./components/App.jsx'导入应用程序；从'./components/FridgePage.jsx'导入FridgePage；ReactDOM.render(<HashRouter><开关><路由精确路径="/" component={App}/><Route path="/fridge" 组件={FridgePage}/></开关></HashRouter>,document.getElementById('root'))

App.jsx

import Header from './Header.jsx';从 'react-router-dom' 导入 {Link}；导出默认类 App 扩展 React.Component {使成为() {console.log(this.props);返回 (<div><h1>Herbnew</h1><Link to="fridge">冰箱</Link>{this.props.children}

);}}

Frid​​gePage.jsx

从'react'导入React；导出默认类 FridgePage 扩展 React.Component {使成为() {返回 (<div><h1>冰箱</h1>你终于找到冰箱了！

);}}

我曾经有一个 div 来包装路由，而不是一个 Switch.在这种情况下，我看到 App 呈现并尝试单击 Fridge 链接，但没有任何反应(Frid​​gePage 未呈现)，并且没有错误输出到控制台.

据我所知，Switch 唯一能做的就是只渲染它匹配的第一个路由，而忽略它的常见问题是同时渲染两个页面.如果我的 "/" 路由是准确的，那么即使没有 Switch，冰箱也应该是唯一匹配的路由，对吧?为什么它根本不渲染?

解决方案

只返回第一个匹配的路由.

exact 返回任意数量的完全匹配的路由.

例如:

<开关><路由精确路径="/animals" component={Animals}/><Route path="/animals/fish" component={Fish}/><路由组件={Missing}/></开关><Route path="/animals" component={Order}/>

如果 Missing 组件不在 <Switch> 中，它将在每条路线上返回.

使用exact，/animals"路由不会捕获包含/animals"的所有路由，例如animals/fish".

如果没有exact，/animals/fish"路由也会返回animals/fish/cod"、/animals/fish/salmon"等的Fish组件.

在 语句之外且没有 exact 的情况下，Order 组件在每个包含/animals"的路径上呈现.

<小时>

通常，如果您不使用精确，您会使用通配符，这样您就不会返回随机页面.

(react-router-dom version: 4.1.1)

I have working routes set up, but I'm a bit confused about why the <Switch> was necessary:

index.js

import React from 'react';
import { HashRouter, Route, Switch } from 'react-router-dom';

import App from './components/App.jsx';
import FridgePage from './components/FridgePage.jsx';

ReactDOM.render(
    <HashRouter>
        <Switch>
            <Route exact path="/" component={App} />
            <Route path="/fridge" component={FridgePage} />
        </Switch>
    </HashRouter>,
    document.getElementById('root')
)

App.jsx

import Header from './Header.jsx';
import {Link} from 'react-router-dom';

export default class App extends React.Component {
    render() {
        console.log(this.props);
        return (
            <div>
                <h1>Herbnew</h1>
                <Link to="fridge">Fridge</Link>
                {this.props.children}
            </div>
        );
    }
}

FridgePage.jsx

import React from 'react';

export default class FridgePage extends React.Component {
    render() {
        return (
            <div>
                <h1>Fridge</h1>
                You finally found the fridge!
            </div>
        );
    }
}

I used to have a div wrapping the routes instead of a Switch. In that case, I see the App rendered and try to click the Fridge link, but nothing happens (the FridgePage isn't rendered), and no error is output into the console.

As I understand it, the only thing the Switch does is exclusively render the first route it matches, and the common problem as a result of omitting it is rendering both pages at once. If my "/" route is exact, then even without the Switch, the Fridge should be the only route that matches, right? Why does it not render at all?

解决方案

<Switch> returns only one first matching route.

exact returns any number of routes that match exactly.

For example:

<Switch>
  <Route exact path="/animals" component={Animals} />
  <Route path="/animals/fish" component={Fish} />
  <Route component={Missing} />
</Switch>
<Route path="/animals" component={Order} />

If the Missing component was not inside a <Switch>, it would be returned on every single route.

With exact, the "/animals" route will not catch every route containing "/animals" such as "animals/fish".

Without exact, the "/animals/fish" route will also return the Fish component for "animals/fish/cod", "/animals/fish/salmon", etc.

Being outside the <Switch> statement and without exact, the Order component is rendered on every path containing "/animals".

---

Usually, if you're not using exact you would use a wildcard, so you don't return random pages.

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