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。