目录

在之前的文章中了解了webpack v4的特性，现在将知识用于实践，对之前写的一个react脚手架进行打包性能的优化。

优化类目

1. 样式分离
2. 第三方资源分离
3. 区分开发环境
4. 热更新
5. 提取公共代码

1. CSS分离

npm install extract-text-webpack-plugin -D

webpack.config.js

将css、less、sass文件单独从打包文件中分离

+ let cssExtract = new ExtractTextWebpackPlugin({
+ filename: 'css.css',
+ allChunks: true
+ });
+ let sassExtract = new ExtractTextWebpackPlugin('sass.css')
+ let lessExtract = new ExtractTextWebpackPlugin('less.css')

在webpack.config.js中单独添加规则，

1. test：匹配处理文件的扩展名的正则表达式
2. include/exclude手动指定必须处理的文件夹或屏蔽不需要处理的文件夹

{
 test: /\.css$/,
 use: cssExtract.extract({
 fallback: "style-loader",
 use: ['css-loader?minimize','postcss-loader'],
 publicPath: "/dist"
 }),
 include:path.join(__dirname,'./src'),
 exclude:/node_modules/
},
{
 test: /\.scss$/,
 use: sassExtract.extract({
 fallback: "style-loader",
 use: ["css-loader?minimize","sass-loader"],
 publicPath: "/dist"
 }),
 include:path.join(__dirname,'./src'),
 exclude:/node_modules/
},
{
 test: /\.less$/,
 loader: lessExtract.extract({
 use: ["css-loader?minimize", "less-loader"]
 }),
 include:path.join(__dirname,'./src'),
 exclude:/node_modules/
},

然后运行webpack命令时报错

compilation.mainTemplate.applyPluginsWaterfall is not a function

Use Chunks.groupsIterable and filter by instanceof Entrypoint instead

研究得出结论：webpack升级到v4然而响应的插件没有升级的原故。

解决方法：安装指定版本的依赖

"html-webpack-plugin": "^3.0.4"
"extract-text-webpack-plugin": "^4.0.0-beta.0"

resolve

指定extension之后可以不用在require或是import的时候加文件扩展名,会依次尝试添加扩展名进行匹配

resolve: {
 //引入模块的时候，可以不用扩展名
 extensions: [".js", ".less", ".json"],
 alias: {//别名
 "bootstrap": "bootstrap/dist/css/bootstrap.css"
 }
}

监听文件修改

webpack模式下使用，webpack-dev-server模式不用，可以将watch改为false

watchOptions: {
 ignored: /node_modules/,
 aggregateTimeout: 300, //监听到变化发生后等300ms再去执行动作，防止文件更新太快导致编译频率太高
 poll: 1000 //通过不停的询问文件是否改变来判断文件是否发生变化，默认每秒询问1000次
}

提取公共代码

optimization: {
 splitChunks: {
 cacheGroups: {
 commons: {
  chunks: "initial",
  minChunks: 2,
  maxInitialRequests: 5, // The default limit is too small to showcase the effect
  minSize: 0 // This is example is too small to create commons chunks
 },
 vendor: {
  test: /node_modules/,
  chunks: "initial",
  name: "vendor",
  priority: 10,
  enforce: true
 }
 }
 }
 }

分离react react-dom ant公共代码

方法一：externals

在页面上引入第三方资源库，然后使用externals防止将某些 import 的包(package)打包到 bundle 中，而是在运行时(runtime)再去从外部获取这些扩展依赖(external dependencies)。

<script src="https://cdn.bootcss.com/react/16.4.0-alpha.0911da3/cjs/react.production.min.js"></script>
<script src="https://cdn.bootcss.com/react-dom/16.4.0-alpha.0911da3/cjs/react-dom-server.browser.production.min.js"></script>
externals: { 'react': 'React', 'react-dom': 'ReactDOM', // 提出ant design的公共资源, }

方法二：DLL

DLL在上篇文章中写过，但是打包后一直出现

后来才发现是页面上没有引入资源。。。。（我一直以为会webpack自动生成在页面上....）

在index.html文件中引入

<script src="./vendor/react.dll.js"></script>

分离成功！上代码

webpack.base.js

var path = require('path');
var webpack = require('webpack');
var ExtractTextWebpackPlugin = require("extract-text-webpack-plugin");
const HtmlWebpackPlugin = require("html-webpack-plugin");
const CleanWebpackPlugin = require('clean-webpack-plugin');
const CopyWebpackPlugin = require('copy-webpack-plugin')

let cssExtract = new ExtractTextWebpackPlugin({
 filename: 'css.css',
 allChunks: true
});
let sassExtract = new ExtractTextWebpackPlugin('sass.css')
let lessExtract = new ExtractTextWebpackPlugin('less.css')

module.exports = {
 entry:'./src/index.js',
 output: {
 path: path.resolve(__dirname, './dist'),
 filename: 'bundle.[hash:8].js',
 publicPath: ''
 },
 resolve: {
 //引入模块的时候，可以不用扩展名
 extensions: [".js", ".less", ".json"],
 alias: {//别名
 "bootstrap": "bootstrap/dist/css/bootstrap.css"
 },
 modules: [path.resolve(__dirname, 'node_modules')]
 },
/* externals: {
 'react': 'React',
 'react-dom': 'ReactDOM',
 // 提出ant design的公共资源
 //'antd': 'antd',
 },*/
 devtool: 'source-map',
 devServer: {
 contentBase:path.resolve(__dirname,'dist'),
 publicPath: '/',
 port: 8080,
 hot:true,
 compress:true,
 historyApiFallback: true,
 inline: true
 },
 watch: false, //只有在开启监听模式时，watchOptions才有意义
 watchOptions: {
 ignored: /node_modules/,
 aggregateTimeout: 300, //监听到变化发生后等300ms再去执行动作，防止文件更新太快导致编译频率太高
 poll: 1000 //通过不停的询问文件是否改变来判断文件是否发生变化，默认每秒询问1000次
 },
 optimization: {
 splitChunks: {
 cacheGroups: {
 commons: {
  chunks: "initial",
  minChunks: 2,
  maxInitialRequests: 5, // The default limit is too small to showcase the effect
  minSize: 0 // This is example is too small to create commons chunks
 },
 vendor: {
  test: /node_modules/,
  chunks: "initial",
  name: "vendor",
  priority: 10,
  enforce: true
 }
 }
 }
 },
 module: {
 rules:[
 {
 test: /\.js$/,
 use: {
  loader:'babel-loader',
  options: {
  presets: ['env','es2015', 'react'],
  }
 },
 include:path.join(__dirname,'./src'),
 exclude:/node_modules/
 },
 {
 test: /\.css$/,
 use: cssExtract.extract({
  fallback: "style-loader",
  use: ['css-loader?minimize','postcss-loader'],
  publicPath: "/dist"
 }),
 include:path.join(__dirname,'./src'),
 exclude:/node_modules/
 },
 {
 test: /\.scss$/,
 use: sassExtract.extract({
  fallback: "style-loader",
  use: ["css-loader?minimize","sass-loader"],
  publicPath: "/dist"
 }),
 include:path.join(__dirname,'./src'),
 exclude:/node_modules/
 },
 {
 test: /\.less$/,
 loader: lessExtract.extract({
  use: ["css-loader?minimize", "less-loader"]
 }),
 include:path.join(__dirname,'./src'),
 exclude:/node_modules/
 },
 {
 test: /\.(html|htm)/,
 use: 'html-withimg-loader'
 },
 {
 test: /\.(png|jpg|gif|svg|bmp|eot|woff|woff2|ttf)/,
 use: {
  loader:'url-loader',
  options:{
  limit: 5 * 1024,
  //指定拷贝文件的输出目录
  outputPath: 'images/'
  }
 }
 }
 ]
 },
 plugins: [
 //定义环境变量
 new webpack.DefinePlugin({
 __development__: JSON.stringify(process.env.NODE_ENV)
 }),
 new CleanWebpackPlugin(['dist']),
 cssExtract,
 lessExtract,
 sassExtract,
 new HtmlWebpackPlugin({
 title: 'React Biolerplate by YuanYuan',
 template: './src/index.html',
 filename: `index.html`,
 hash: true
 }),
 new webpack.DllReferencePlugin({
 manifest: path.join(__dirname, 'vendor', 'react.manifest.json')
 }),
 new CopyWebpackPlugin([{
 from: path.join(__dirname,'vendor'),//静态资源目录源地址
 to:'./vendor' //目标地址，相对于output的path目录
 }]),
/* new webpack.optimize.CommonsChunkPlugin({
 name: 'common' // 指定公共 bundle 的名称。
 + })*/
 new webpack.HotModuleReplacementPlugin(), // 热替换插件
 new webpack.NamedModulesPlugin() // 执行热替换时打印模块名字
 ]
};

webpack.config.js

const path = require('path');
const webpack = require('webpack');
const merge = require('webpack-merge');//用来合并配置文件
const base = require('./webpack.base');
let other = '';

//console.log(process.env.NODE_ENV )
if (process.env.NODE_ENV == 'development') {
 other = require('./webpack.dev.config');
} else {
 other = require('./webpack.prod.config');
}
//console.log(merge(base, other));

module.exports = merge(base, other);
webpack.prod.config.js

const path = require('path');
const webpack = require('webpack');
const UglifyJSPlugin = require('uglifyjs-webpack-plugin')

module.exports = {
 output: {
 filename: 'bundle.min.js',
 },
 plugins: [
 new UglifyJSPlugin({sourceMap: true})
 ]
}

原脚手架地址

优化后手架地址

打包速度优化，打包文件细化，改造成功~

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。