本文基于 Webpack v4 特性,对 React 脚手架进行打包性能优化。主要涵盖样式文件分离、第三方资源(React/antd)通过 externals 或 DLL 方式剥离、开发环境区分及热更新配置。针对 Webpack 4 升级中遇到的插件兼容报错,提供了版本锁定解决方案,并展示了公共代码提取与优化后的配置细节。
Webpack 4 React 项目优化背景
在前文介绍 Webpack v4 特性的基础上,本文将这些知识应用于实践,针对此前构建的一个 React 项目脚手架进行打包性能的优化处理。
优化方向概览
本次优化的主要方向包括以下几个方面:
- 样式文件分离处理
- 第三方依赖资源分离
- 区分开发与生产环境配置
- 启用模块热更新机制
- 提取并复用公共代码
样式分离与插件兼容处理
具体实施步骤如下:
npm install extract-text-webpack-plugin -D
配置文件为 webpack.config.js
首先,将 CSS、Less 以及 Sass 文件从主打包 bundle 中单独分离出来,以减少主包体积。
+ 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 中单独添加对应的处理规则,具体配置如下:
- test 属性用于匹配需要处理的文件扩展名正则表达式
- include 和 exclude 用于手动指定必须处理的文件夹路径,或屏蔽不需要处理的目录
{
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/
},
配置完成后运行 webpack 命令时,控制台报错提示:
compilation.mainTemplate.applyPluginsWaterfall is not a function
Use Chunks.groupsIterable and filter by instanceof Entrypoint instead
经排查发现,这是由于 Webpack 已升级至 v4 版本,但相关的插件(如 extract-text-webpack-plugin)未同步升级所致。
解决方法是安装指定兼容版本的依赖包:
"html-webpack-plugin": "^3.0.4"
"extract-text-webpack-plugin": "^4.0.0-beta.0"
此外,配置 resolve 字段
指定 extensions 后,在 require 或 import 模块时即可省略文件扩展名,Webpack 会依次尝试添加配置的扩展名进行匹配
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"
}
}
关于文件监听配置
在纯 webpack 模式下使用 watch 选项,若使用 webpack-dev-server 则无需此配置,可将 watch 设为 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
}
第三方资源与公共代码分离策略
接下来处理公共代码的提取与分离
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
}
}
}
}
目标是将 React、react-dom 以及 antd 等公共代码进行分离,避免重复打包
方法一:使用 externals 配置
在 HTML 页面中直接引入第三方资源库,并在配置中使用 externals 防止将某些 import 的包打包到最终的 bundle 中。这些扩展依赖将在运行时从外部获取。
<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:使用 DLL 插件
DLL 机制在前文已有提及,但在实际打包后一直出现资源加载问题

后来发现原因是 HTML 页面中并未引入生成的 DLL 资源文件(此前误以为 Webpack 会自动在页面中注入)
需要在 index.html 文件中手动引入生成的 DLL 脚本:
<script src="./vendor/react.dll.js"></script>
至此,资源分离配置成功。以下是相关代码片段:
基础配置文件 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
]
};
主配置文件 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})
]
}
原始脚手架项目地址

优化后的脚手架项目地址

经过上述优化,打包速度得到提升,打包文件结构更加细化,改造顺利完成。
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本站。