• 第一种方法 移除resolve('node_modules/webpack-dev-server/client')
webpack.base.conf.js

module.exports = { ... module: { rules: [ { test: /\.js$/, loader: 'babel-loader' // include: [resolve('src'), resolve('test'), resolve('node_modules/webpack-dev-server/client')] include: [resolve('src'),resolve('test')], exclude: /node_modules/ },] } }

• 第二种方法 移除transform-runtime
.babelrc

{ "presets": [ ["env", { "modules": false, "targets": { "browsers": ["> 1%", "last 2 versions", "not ie <= 8"] } }], "stage-2" ], // "plugins": ["transform-vue-jsx", "transform-runtime"] "plugins": ["transform-vue-jsx"] }

const webpackConfig = merge(baseWebpackConfig, { ..., mode: 'production' })

• webpack.optimize.CommonsChunkPlugin
• webpack.optimize.CommonsChunkPlugin
• webpack.optimize.CommonsChunkPlugin
• webpack.optimize.ModuleConcatenationPlugin
• OptimizeCSSPlugin
• UglifyJsPlugin

const webpackConfig = merge(baseWebpackConfig, { ..., plugins: [ //new webpack.optimize.CommonsChunkPlugin(), //new webpack.optimize.CommonsChunkPlugin({}), //new webpack.optimize.CommonsChunkPlugin({})， //new webpack.optimize.ModuleConcatenationPlugin(), //new OptimizeCSSPlugin({}), //new UglifyJsPlugin({}) ], })

const webpackConfig = merge(baseWebpackConfig, { ..., optimization: { //取代 new UglifyJsPlugin minimizer: [ // 压缩代码 new UglifyJsPlugin({ uglifyOptions: { compress: { warnings: false, drop_debugger: true,//关闭debug drop_console: true,//关闭console } }, sourceMap: config.build.productionSourceMap, parallel: true }), // 可自己配置，建议第一次升级先不配置 new OptimizeCSSPlugin({ // cssProcessorOptions: config.build.productionSourceMap //? {safe: true, map: {inline: false}, autoprefixer: false} //: {safe: true} }), ], // 识别package.json中的sideEffects以剔除无用的模块，用来做tree-shake // 依赖于optimization.providedExports和optimization.usedExports sideEffects: true, // 取代 new webpack.optimize.ModuleConcatenationPlugin() concatenateModules: true, // 取代 new webpack.NoEmitOnErrorsPlugin()，编译错误时不打印输出资源。 noEmitOnErrors: true, splitChunks: { cacheGroups: { vendors: { test: /[\\/]node_modules[\\/]/, chunks: 'initial', name: 'vendors', }, 'async-vendors': { test: /[\\/]node_modules[\\/]/, minChunks: 2, chunks: 'async', name: 'async-vendors' } } }, runtimeChunk: { name: 'runtime' } }, })

• utils.js

// const ExtractTextPlugin = require('extract-text-webpack-plugin') const MiniCssExtractPlugin = require('mini-css-extract-plugin')exports.cssLoaders = function (options) { ... // Extract CSS when that option is specified // (which is the case during production build) // if (options.extract) { //return ExtractTextPlugin.extract({ //use: loaders, //fallback: 'vue-style-loader', //publicPath: '../../', //注意: 此处根据路径, 自动更改,添加publicPath，可以在css中使用背景图 //}) // } else { //return ['vue-style-loader'].concat(loaders) // } return [ options.extract ? MiniCssExtractPlugin.loader : 'vue-style-loader', ].concat(loaders) }

• webpack.prod.conf.js
  添加mini-css-extract-plugin,移除ExtractTextPlugin

//const ExtractTextPlugin = require('extract-text-webpack-plugin') const MiniCssExtractPlugin = require('mini-css-extract-plugin') const webpackConfig = merge(baseWebpackConfig, { ..., plugins: [ new MiniCssExtractPlugin({ filename: utils.assetsPath('css/[name].[contenthash].css'), allChunks: true, }), // new ExtractTextPlugin({ //filename: utils.assetsPath('css/[name].[contenthash].css'), // Setting the following option to `false` will not extract CSS from codesplit chunks. // Their CSS will instead be inserted dynamically with style-loader when the codesplit chunk has been loaded by webpack. // It's currently set to `true` because we are seeing that sourcemaps are included in the codesplit bundle as well when it's `false`, // increasing file size: https://github.com/vuejs-templates/webpack/issues/1110 //allChunks: true, // }), ] })

if (options.extract) { return ExtractTextPlugin.extract({ use: loaders, fallback: 'vue-style-loader', publicPath: '../../', //注意: 此处根据路径, 自动更改,添加publicPath，可以在css中使用背景图 }) } else { return ['vue-style-loader'].concat(loaders) }

return [ options.extract ? MiniCssExtractPlugin.loader : 'vue-style-loader', ].concat(loaders)

return [ options.extract ? {loader:MiniCssExtractPlugin.loader, options: {publicPath: '../../'}} : 'vue-style-loader', ].concat(loaders)

1. 如果你的项目中使用了web worker,那么你在升级到webpack4运行dev的时候，会出现报错，如下：
   Uncaught ReferenceError: window is not defined
   
   文章图片
   
   其实在worker-loader插件的issues已经有了解决办法，想要了解更多，请戳我
   解决办法: 在webpack.base.conf.js文件下加入globalObject: 'this'

module.exports = { ... output: { path: config.build.assetsRoot, filename: '[name].js', publicPath: process.env.NODE_ENV === 'production' ? config.build.assetsPublicPath : config.dev.assetsPublicPath, globalObject: 'this' } }

Vue packages version mismatch: - vue@2.5.21 - vue-template-compiler@2.5.16 This may cause things to work incorrectly. Make sure to use the same version for both. If you are using vue-loader@>=10.0, simply update vue-template-compiler. If you are using vue-loader@<10.0 or vueify, re-installing vue-loader/vueify should bump vue-template-compiler to the latest. @ ./resources/assets/js/app.js 12:13-46 @ multi ./resources/assets/js/app.js ./resources/assets/sass/app.scss ERROR in ./resources/assets/js/components/steps.vue Module build failed (from ./node_modules/vue-loader/lib/index.js): TypeError: Cannot read property 'parseComponent' of undefined

3. 如果你的项目使用了eslint报错

TypeError: Cannot read property 'eslint' of undefined

const HappyPack = require('happypack') const os = require('os') // 创建 happypack 共享进程池 const happyThreadPool = HappyPack.ThreadPool({size: os.cpus().length}) module.exports = { ... module: { rules: [ ... { test: /\.js$/, //loader: 'babel-loader', use: ['happypack/loader?id=babel'], // include: [resolve('src'), resolve('test'), resolve('node_modules/webpack-dev-server/client')] include: [resolve('src'),resolve('test')], exclude: /node_modules/ } ] }, plugins: [ new HappyPack({ /* * 必须配置项 */ // id 标识符，要和 rules 中指定的 id 对应起来 id: 'babel', // 需要使用的 loader，用法和 rules 中 Loader 配置一样 // 可以直接是字符串，也可以是对象形式 loaders: ['babel-loader?cacheDirectory'], // 使用共享进程池中的进程处理任务 threadPool: happyThreadPool, verbose: true }) ] }

const path= require('path'); const webpack = require('webpack'); const dllConfig= require('./webpack.dll.conf'); const chalk = require('chalk') const rm= require('rimraf') const ora = require('ora') const spinner = ora({ color: 'green', text: '正为生产环境打包dll包中...' }) spinner.start() rm(path.resolve(__dirname, '../dll'),err => { if (err) throw err webpack(dllConfig,function (err, stats) { spinner.stop() if (err) throw err process.stdout.write(stats.toString({ colors: true, modules: false, children: false, chunks: false, chunkModules: false }) + '\n\n') console.log(chalk.cyan('dll打包已完成啦!\n')) }) });

const path = require('path') const webpack = require('webpack') const CleanWebpackPlugin = require('clean-webpack-plugin') const AssetsPlugin = require('assets-webpack-plugin') module.exports = { mode: 'development', entry: { vendor: [ 'vue/dist/vue.esm.js' ] }, output: { path: path.join(__dirname, '../static/js/'), // 生成的文件存放路径 filename: 'dll.[name].[chunkhash].js', // 生成的文件名字(默认为dll.vendor.[hash].js) library: '[name]_[chunkhash]' // 生成文件的映射关系，与下面DllPlugin中配置对应 }, plugins: [ new CleanWebpackPlugin(['dll','../static/js']), new webpack.DllPlugin({ // 会生成一个json文件，里面是关于dll.js的一些配置信息 path:path.join(__dirname, '../dll/[name]-manifest.json'), name: '[name]_[chunkhash]', // 与上面output中配置对应 context: __dirname // 上下文环境路径（必填，为了与DllReferencePlugin存在与同一上下文中） }), new AssetsPlugin({// filename: 'bundle-conf.json', path: './dll' }) ] }

4. 安装依赖npm i -D clean-webpack-plugin@latest assets-webpack-plugin@latest
   5.在webpack.prod.conf.js文件下

const AddAssetHtmlPlugin = require('add-asset-html-webpack-plugin') const CleanWebpackPlugin = require('clean-webpack-plugin') const boundConf = require('../dll/bundle-conf.json') //bundle-confi.json目录结构要正确 const webpackConfig = merge(baseWebpackConfig, { ... plugins: [ new CleanWebpackPlugin(['dist']), new webpack.DllReferencePlugin({ context: __dirname, manifest: require('../dll/vendor-manifest.json') }), //这个主要是将生成的vendor.dll.js文件加上hash值插入到页面中。 new AddAssetHtmlPlugin([{ filepath: path.resolve(`./static/js/${boundConf.vendor.js}`), outputPath: utils.assetsPath('js'), publicPath: path.posix.join(config.build.assetsPublicPath, 'static/js'), includeSourcemap: false, hash: true, }]), ] })

5. 在package.sjon下添加配置"build:dll": "node build/dll.js",

"scripts": { "dev": "webpack-dev-server --inline --progress --config build/webpack.dev.conf.js", "start": "npm run dev", "build": "node build/build.js", "build:dll": "node build/dll.js" },

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