react-router4按需加载(踩坑填坑)

react-router4如何去实现按需加载Component，在router4以前，我们是使用getComponent的方式来实现按

react-router4如何去实现按需加载Component，在router4以前，我们是使用getComponent的方式来实现按需加载的，router4中，getComponent方法已经被移除，网上有好几种方案大多都解决的不太彻底，下面我说一下我的方案：

一：创建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;
 }
 
 render() {
 const C = this.state.component;

 return C ? <C {...this.props} /> : null;
 }
 }

 return AsyncComponent;
}

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 ? <C {...this.props} /> : null;
 }
 }

 return AsyncComponent;
}

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脚本之家。