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react-router4按需加載(踩坑填坑)

 更新時(shí)間：2019年01月06日 15:24:57   作者：墨子攻城  
這篇文章主要介紹了react-router4按需加載(踩坑填坑)，小編覺得挺不錯(cuò)的，現(xiàn)在分享給大家，也給大家做個(gè)參考。一起跟隨小編過來(lái)看看吧

react-router4如何去實(shí)現(xiàn)按需加載Component，在router4以前，我們是使用getComponent的方式來(lái)實(shí)現(xiàn)按需加載的，router4中，getComponent方法已經(jīng)被移除，網(wǎng)上有好幾種方案大多都解決的不太徹底，下面我說(shuō)一下我的方案：

一：創(chuàng)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,并導(dǎo)入需要按需加載的模塊

 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：預(yù)覽效果

可以看到有一個(gè)警告，內(nèi)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

這個(gè)警告其實(shí)是在組件卸載的時(shí)候執(zhí)行了setState，雖然這個(gè)警告并不影響正常使用，但是看著總是不爽，所以我們要在組件卸載的時(shí)候結(jié)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',
 },

結(jié)尾推廣一下我的react-native開源項(xiàng)目：https://github.com/duheng/Mozi

以上就是本文的全部?jī)?nèi)容，希望對(duì)大家的學(xué)習(xí)有所幫助，也希望大家多多支持腳本之家。

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