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 "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

react-router4按需加载(踩坑填坑)

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。

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