Detailed explanation of routing in React

This time I will bring you a detailed explanation of the use of routing in React. What are the precautions for using routing in React? The following is a practical case, let's take a look.

Routing

is implemented by mapping the URL to the corresponding function. To use React routing, react-router.js must be introduced first.
Note:
There is a big difference between version 4.0 and above of react-router and version 3.0 and below. This tutorial uses version 3.0.2, and tutorials for versions 4.0 and above will be updated later.
When installing using npm, the latest version is installed by default. If the installed version is the latest and the 3.0 version is used, an error will be reported.
So you need to specify the version when installing npm npm install react-router@3.0.2 --save-dev.

Routing Background-SPA

The traditional front-end basically switches between functional modules by jumping between pages. This approach will lead to a large number of html pages in a project. Moreover, each page has a lot of static resource files that need to be imported, which has always been a problem in terms of performance. Later, with the popularity of ajax and the convenient use of jQuery's encapsulation of ajax, developers will use ajax extensively to load an html page into a container of the current page to achieve non-refresh loading, but there is still no Solve the performance problems caused by the presence of a large number of html pages and the loading of a large number of static resource files on each page. With the popularity of mobile Internet, mobile terminals have increasingly higher performance requirements and traffic restrictions on page loading, so mainstream front-end frameworks are moving towards SPA.
SPA, the abbreviation of Single Page Application, single page application, its purpose is that the entire application has only one html page, combined with the unified packaging idea of ​​building webpack, packages all static resource files into a js file, in the only html page Page reference, thus truly realizing the idea of ​​an html file and a js file completing an application.
SPA optimizes the performance of static loading, but an application still has many functional modules. Switching between functional modules becomes switching between components, so so far, basically the mainstream front-end frameworks will There are two concepts of routing and components, and the implementation ideas are consistent.

Routing reference and usage

//es5
var {Router, Route, hashHistory, Link, IndexRoute, browserHistory} = require("react-router");

//es6
import {Router, Route, hashHistory, Link, IndexRoute, browserHistory} from 'react-router';

//es5 和 es6 的使用都是一样的
<Link to="/">Root</Link>
<Router>
    <Route path=&#39;/&#39; component={RootComponent}/>
</Router>

//使用 `<script>` 标签 
<script src="../js/ReactRouter.js"></script>
<ReactRouter.Link to="/">Root</ReactRouter.Link>
<ReactRouter.Router>
    <ReactRouter.Route path=&#39;/&#39; component={RootComponent}/>
</ReactRouter.Router>

Routing components and attributes

Link

• is used to jump between routes, the function is the same Tags a. The

• attribute to is equivalent to the href of the a tag.

• ##page, the function is equivalent to page.

Router

• is the outermost routing component, and there is only one in the entire Application.

• Attribute

  history has two attribute values:

• hashHistory The route will Switching through the hash part (#) of the URL is recommended.

• ##

  The corresponding URL format is similar to example.com/#/some/path

• browserHistory

  This situation requires server modification. Otherwise, the user directly requests a certain sub-route from the server, and a 404 error indicating that the web page cannot be found will be displayed.

##
• The corresponding URL format is similar to example.com/some/path.

Route component's properties

Route
• is a subcomponent of component

  Router, Route nesting can be achieved by nesting route.

  Attribute
path
• : Specifies the matching rule of the route. This attribute can be omitted. In this case, the specified component will always be loaded regardless of whether the path matches or not.
  Attribute
component
• : Refers to the corresponding component that will be rendered when the URL is mapped to the matching rule of the route.
  ##
When the URL is example.com/#/, the component RootComponent## will be rendered.

• #

  When the URL is example.com/#/page1, the component Page1Component## will be rendered.

• #Basic usage<div class="code" style="position:relative; padding:0px; margin:0px;"><pre class="brush:php;toolbar:false">import React from 'react' import ReactDOM from 'react-dom' import {Router, hashHistory, browserHistory} from 'react-router' const html = (     &lt;ul&gt;         &lt;li&gt;&lt;Link to=&quot;/&quot;&gt;Root&lt;/Link&gt;&lt;/li&gt;         &lt;li&gt;&lt;Link to=&quot;/page&quot;&gt;page&lt;/Link&gt;&lt;/li&gt;     &lt;/ul&gt; ) class RootComponent extends React.Component{     render(){         return (             &lt;p&gt;                 &lt;h1&gt;RootComponent&lt;/h1&gt;                 {html}             &lt;/p&gt;         )            } } class PageComponent extends React.Component{     render(){         return (             &lt;p&gt;                 &lt;h1&gt;PageComponent&lt;/h1&gt;                 {html}             &lt;/p&gt;         )            } } ReactDOM.render(     &lt;Router history={hashHistory}&gt;         &lt;Route path=&amp;#39;/&amp;#39; component={RootComponent}/&gt;         &lt;Route path=&amp;#39;/page&amp;#39; component={PageComponent}/&gt;     &lt;/Router&gt;,     document.getElementById('app') )</pre><div class="contentsignin">Copy after login</div></div>Effect preview

Routing parameters

Routing parameters are passed through the Route component path attribute to specify.

The parameter value can be obtained through
• this.props.params.paramName

  .

• :paramName

• Matches one part of the URL until it encounters the next /,?, #until.

• .

• Matching URL: /#/user/sam, the parameter sam must exist.

• The value of this.props.params.name

  is sam.

import React from 'react'
import ReactDOM from 'react-dom'
import {Router, hashHistory, browserHistory} from 'react-router'

class UserComponent extends React.Component{
    render(){
        return (
            <p>
                <h3>UserComponent 单个参数 </h3>
                <p>路由规则：path='/user/:username'</p>
                <p>URL 映射：{this.props.location.pathname}</p>
                <p>username：{this.props.params.username}</p>
            </p>
        )       
    }
}
ReactDOM.render(
    <Router history={hashHistory}>
        <Route path=&#39;/user/:username&#39; component={UserComponent}/>
    </Router>,
    document.getElementById('app')
)

• (:paramName)

• 表示URL的这个部分是可选的。

• <Route path="/order(/:orderid)"> 。

• 匹配 URL：/#/order，this.props.params.orderid 获取的值为 undefined。

• 匹配 URL：/#/order/001，this.props.params.orderid获取参数的值为 001。

import React from 'react'
import ReactDOM from 'react-dom'
import {Router, hashHistory, browserHistory} from 'react-router'

class UserComponent extends React.Component{
    render(){
        return (
            <p>
                <h3>OrderComponent 可选参数 </h3>
                <p>路由规则：path='/order(/:orderid)'</p>
                <p>URL 映射：{this.props.location.pathname}</p>
                <p>orderid：{this.props.params.orderid}</p>
            </p>
        )       
    }
}
ReactDOM.render(
    <Router history={hashHistory}>
        <ReactRouter.Route path=&#39;/order(/:orderid)&#39; component={UserComponent}/>
    </Router>,
    document.getElementById('app')
)

• *.*

• 匹配任意字符，直到模式里面的下一个字符为止。匹配方式是非贪婪模式。

• <Route path="/all1/*.*"> 。

• this.props.params 获取的参数为一个固定的对象： {splat: [*, *]}。

• 匹配 URL：/all1/001.jpg，参数为 {splat: ['001', 'jpg']}。

• 匹配 URL：/all1/001.html，参数为 {splat: ['001', 'html']}。

• *

• 匹配任意字符，直到模式里面的下一个字符为止。匹配方式是非贪婪模式。

• <Route path="/all2/*">。

• this.props.params 获取的参数为一个固定的对象： {splat: '*'}。

• 匹配 URL：/all2/，参数为 {splat: ''}。

• 匹配 URL：/all2/a，参数为 {splat: 'a'}。

• 匹配 URL：/all2/a/b，参数为 {splat: 'a/b'}。

• **

• 匹配任意字符，直到下一个/、?、#为止。匹配方式是贪婪模式。

• <Route path="/**/*.jpg">

• this.props.params 获取的参数为一个固定的对象： {splat: [**, *]}。

• 匹配 URL：/all3/a/001.jpg，参数为 {splat: ['a', '001']}。

• 匹配 URL：/all3/a/b/001.jpg，参数为 {splat: ['a/b', '001']}。

效果预览

IndexRoute

当访问一个嵌套路由时，指定默认显示的组件

AppComponent.js

import React from 'react'

export default class AppComponent extends React.Component{
    render(){
        return <p>{this.props.children}</p>
    }
}

LoginComponent.js

import React, {Component} from 'react'

export default class LoginComponent extends Component{
    login(){}
    render(){
        return <h1>Login</h1>
    }
}

HomeComponent.js

import React, {Component} from 'react'

export default class HomeComponent extends Component{
    login(){}
    render(){
        return <h1>Home</h1>
    }
}

Router.js

import React from 'react'
import {Route, IndexRoute} from 'react-router'

import AppComponent from '../components/app/app'
import HomeComponent from '../components/home/home'
import LoginComponent from '../components/login/login'

const routes = (
    <Route path="/" component={AppComponent}>
        <IndexRoute component={HomeComponent} />
        <Route path="login" component={LoginComponent} />
        <Route path="home" component={HomeComponent} />
    </Route>
)

export default routes;

• 如果没有加IndexRoute，则在访问 http://localhost/#/ 时页面是空白的

• 访问 http://localhost/#/login 才会显示内容

• 加上 IndexRoute，在访问http://localhost/#/时会默认渲染HomeComponent

模块化

可利用组件Router的属性routes来实现组件模块化

router.js

import React from 'react'
import ReactDOM from 'react-dom'

import {Route, Router, IndexRoute, hashHistory} from 'react-router'

import AppComponent from '../components/app/app'
import HomeComponent from '../components/home/home'
import LoginComponent from '../components/login/login'

const routes = (
    <Route path="/" component={AppComponent}>
        <IndexRoute component={HomeComponent} />
        <Route path="login" component={LoginComponent} />
        <Route path="home" component={HomeComponent} />
    </Route>
)

ReactDOM.render(
    <Router history={hashHistory} routes={routes} />,
    document.getElementById('app')
)

编程式导航

• 普通跳转 this.props.router.push('/home/cnode')

• 带参数跳转this.props.router.push({pathname: '/home/cnode', query: {name: 'tom'}})

路由钩子函数

每个路由都有enter和leave两个钩子函数，分别代表用户进入时和离开时触发。

onEnter

进入路由/home前会先触发onEnter方法，如果已登录，则直接next()正常进入目标路由，否则就先修改目标路径replace({ pathname: 'login' })，再next()跳转。

let isLogin = (nextState, replace, next) => {
    if(window.localStorage.getItem('auth') == 'admin'){
        next()
    } else {
        replace({ pathname: 'login' })
        next();
    }
    
}
const routes = (
    <Route path="/" component={AppComponent}>
        <Route path="login" component={LoginComponent} />
        <Route path="home" component={HomeComponent} onEnter={isLogin}/>
    </Route>
)

onLeave

对应的setRouteLeaveHook方法，如果return true则正常离开，否则则还是停留在原路由

import React from 'react'
import {Link} from 'react-router'

export default class Component1 extends React.Component{
    componentDidMount(){
        this.props.router.setRouteLeaveHook(
            this.props.route,
            this.routerWillLeave
        )
    }
    routerWillLeave(){
        return '确认要离开？'
    }
    render(){
        return (
            <p>
                <Link to="/login">Login</Ling>
            </p>
        )
    }
}

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