1.lazyLoad用处

默认例如首页，如果有好十几个甚至百个路由，react是会默认一下全部把路由组件一下全部加载的，极可能造成页面卡顿。react lazyLoad就可以解决这个问题。

2.使用

我用的react版本是18,注意在主index.js中<React.StrictMode>要去掉，不然会出现路由变化了，控制台也不报错但是页面不跳转的问题.
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2.1 react-router-dom5版本写法

import React, { Component,lazy,Suspense} from 'react'
import {NavLink,Route} from 'react-router-dom'

import Loading from './Loading'
const Home = lazy(()=> import('./Home') )
const About = lazy(()=> import('./About'))

export default class Demo extends Component {
	render() {
		return (
			<div>
				<div className="row">
					<div className="col-xs-offset-2 col-xs-8">
						<div className="page-header"><h2>React Router Demo</h2></div>
					</div>
				</div>
				<div className="row">
					<div className="col-xs-2 col-xs-offset-2">
						<div className="list-group">
							{/* 在React中靠路由链接实现切换组件--编写路由链接 */}
							<NavLink className="list-group-item" to="/about">About</NavLink>
							<NavLink className="list-group-item" to="/home">Home</NavLink>
						</div>
					</div>
					<div className="col-xs-6">
						<div className="panel">
							<div className="panel-body">
								 {/* fallback可以写一个组件,但是这个组件就不能懒加载了，本来的作用就是如果网络等原因导致页面空白的话就用组件来替代 */}
								<Suspense fallback={<Loading/>}>
									{/* 注册路由 */}
									<Route path="/about" component={About}/>
									<Route path="/home" component={Home}/>
								</Suspense>
							</div>
						</div>
					</div>
				</div>
			</div>
		)
	}
}

2.2 react-router-dom6版本写法

主要是引入和Suspense的改变

import React, { Component, lazy, Suspense } from "react";
import { NavLink, Route,Routes } from "react-router-dom";

import Loading from "./Loading";
const Home = lazy(() => import("./Home"));
const About = lazy(() => import("./About"));

export default class Demo extends Component {
  render() {
    return (
      <div>
        <div className="row">
          <div className="col-xs-offset-2 col-xs-8">
            <div className="page-header">
              <h2>React Router Demo</h2>
            </div>
          </div>
        </div>
        <div className="row">
          <div className="col-xs-2 col-xs-offset-2">
            <div className="list-group">
              {/* 在React中靠路由链接实现切换组件--编写路由链接 */}
              <NavLink className="list-group-item" to="/about">
                About
              </NavLink>
              <NavLink className="list-group-item" to="/home">
                Home
              </NavLink>
            </div>
          </div>
          <div className="col-xs-6">
            <div className="panel">
              <div className="panel-body">
                {/* fallback可以写一个组件,但是这个组件就不能懒加载了，本来的作用就是如果网络等原因导致页面空白的话就用组件来替代 */}
                <Suspense fallback={<Loading />}>
                  {/* 注册路由 */}
                  <Routes>
                    <Route path="/about" element={<About/>} />
                    <Route path="/home" element={<Home/>} />
                  </Routes>
                </Suspense>
              </div>
            </div>
          </div>
        </div>
      </div>
    );
  }
}