react-router4按需加载(踩坑填坑)

import React, { Component } from "react";

export default function asyncComponent(importComponent) {
 class AsyncComponent extends Component {
 constructor(props) {
  super(props);

  this.state = {
  component: null
  };
 }

 async componentDidMount() {
  if(this.hasLoadedComponent()){
   return;
  }
  const { default: component } = await importComponent();
  this.setState({
  component: component
  });
 }

 hasLoadedComponent() {
  return this.state.component !== null;
 }
 
 render() {
  const C = this.state.component;

  return C "color: #ff0000">二：在引入asyncComponent.js,并导入需要按需加载的模块




 import asyncComponent from "utils/asyncComponent"

 const Home = asyncComponent(() => import("./home"))
 const About = asyncComponent(() => import("./about"))




二：render部分




 const routes = () => (
 <BrowserRouter>
  <Switch>
   <Route exact path="/" component={Home} />
   <Route exact path="/about" component={About} />
   <Redirect to="/" />
  </Switch>
 </BrowserRouter>
)



三：预览效果

可以看到有一个警告，内容是



Warning: Can't perform a React state update on an unmounted component. This is a no-op, but it indicates a memory leak in your application. To fix, cancel all subscriptions and asynchronous tasks in the componentWillUnmount method



这个警告其实是在组件卸载的时候执行了setState，虽然这个警告并不影响正常使用，但是看着总是不爽，所以我们要在组件卸载的时候结束setState，如下：




componentWillUnmount(){
 this.setState = (state,callback)=>{
  return
  }
}



四：完整版asyncComponent.js




import React, { Component } from "react";

export default function asyncComponent(importComponent) {
 class AsyncComponent extends Component {
 constructor(props) {
  super(props);

  this.state = {
  component: null
  };
 }

 async componentDidMount() {
  if(this.hasLoadedComponent()){
   return;
  }
  const { default: component } = await importComponent();
  this.setState({
  component: component
  });
 }

 hasLoadedComponent() {
  return this.state.component !== null;
 }
 componentWillUnmount(){
  this.setState = (state,callback)=>{
  return
  }
 }

 render() {
  const C = this.state.component;

  return C "color: #ff0000">五： webpack部分配置需要配置chunkFilename




eturn {
 output: {
  path: path.resolve(CWD, config.build),
  publicPath: config.static[process.env.MODE],
  chunkFilename: 'js/[name]-[chunkhash:8].js',
  filename: 'js/[name].js',
 },



结尾推广一下我的react-native开源项目：https://github.com/duheng/Mozi
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。