React lazyLoad懒加载

在React中使用lazy懒加载
效果图

目录结构

index.js

import React from "react";
import ReactDOM from "react-dom";
import App from "./App";
import { BrowserRouter } from "react-router-dom";

ReactDOM.render(
  <BrowserRouter>
    <App />
  </BrowserRouter>,
  document.getElementById("root")
);
/*  */

App.js

import React, { Component } from 'react'
import Demo from './components/2_lazyLoad'

export default class App extends Component {
  render() {
    return (
      <div>
          <Demo/>
      </div>
    )
  }
}

2_lazyLoad/index.jsx

import React, { Component, lazy, Suspense } from "react";
import { NavLink, Route, Routes } from "react-router-dom";
// import Home from "./Home";
// import About from "./About";
import Loading from './Loading'
const Home = lazy(() => import("./Home"));
const About = lazy(() => import("./About"));
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">
            {/* 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 className="col-xs-6">
            <div className="panel">
              <div className="panel-body">
                <Suspense fallback={<Loading/>}>
                  <Routes>
                    <Route path="" element={<About />} />
                    <Route path="/about" element={<About />} />
                    <Route path="/home" element={<Home />} />
                  </Routes>
                  {/* 注册路由 */}
                </Suspense>
              </div>
            </div>
          </div>
        </div>
      </div>
    );
  }
}

export default Demo;

2_lazyLoad/About/index.jsx

import React, { Component } from 'react'

export default class About extends Component {
  render() {
    return (
      <div><h2>About组件</h2></div>
    )
  }
}

2_lazyLoad/Home/index.jsx

import React, { Component } from 'react'

export default class Home extends Component {
  render() {
    return (
      <div><h2>Home组件</h2></div>
    )
  }
}

2_lazyLoad/Loading/index.jsx

import React, { Component } from 'react'

export default class Loading extends Component {
  render() {
    return (
      <div>
          <h1 style={{backgroundColor:'orange',color:'green'}}>Loading...</h1>
      </div>
    )
  }
}