一次webpack3升级为webpack4的实践

这次webpack升级提升了不少构建速度：生产打包提升了30%；开发构建提升40%，开发热更新提升70%

之前尝试过一些在webpack3的基础上做的构建优化，例如引入HappyPack优化构建速度，开启loader缓存和优化包查找路径等等，详情可以查看前端webpack构建优化

但是随着时间的推移，这种优化产生的效果越来越弱化，手上的项目体积越来越大，对本地开发热更新速度和生产打包发布速度都有了很大的影响。

webpack3升级到webpack4迫在眉睫，这篇博文将记录一些我在升级过程中遇到的坑。

当你遇到这些坑时，通过搜索引擎找到我这篇文章，如果能够解决了手上的webpack配置问题，然后发自内心的感到 ”Save my day！“，”It helps me！“，”Solved my problem！“，”Works for me！“ ，我会感觉自己的这篇博文很有意义。

• 升级到 webpack 4
• 移除 CommonsChunkPlugin，默认使用 SplitChunksPlugin 分割代码
• 升级 html-webpack-plugin
• 移除 extract-text-webpack-plugin，引入 mini-css-extract-plugin 并配置 css-loader
• 配置 mode 属性
• 升级 vue-loader 到 v14.2.2
• 更新 HtmlWebpackPlugin 的 chunkSortMode
• 修复大小限制的报错
• 重命名 app.js，生成 vendors.js
• mini-css-extract-plugin 的配置放在 webpack.base.conf.js
• 调试开发环境可用
• 引入analyzer分析分析包大小
• webpack3与webpack4打包对比
• 文件可以更小一些吗？构建速度可以更快一些吗？
• 升级vue-loader到v15并且替换happyPack为thread-loader
• webpack3与webpack4开发依赖对比
• 总结

升级 webpack 到 4

"webpack": "^3.6.0" -> "webpack": "^4.43.0"

yarn add -D [email protected]

移除 CommonsChunkPlugin

plugins: [
  // // split vendor js into its own file
  // new webpack.optimize.CommonsChunkPlugin({
  //   name: 'vendor',
  // }),
  // // extract webpack runtime and module manifest to its own file in order to
  // // prevent vendor hash from being updated whenever app bundle is updated
  // new webpack.optimize.CommonsChunkPlugin({
  //   name: 'manifest',
  //   minChunks: Infinity,
  // }),
  // // This instance extracts shared chunks from code splitted chunks and bundles them
  // // in a separate chunk, similar to the vendor chunk
  // // see: https://webpack.js.org/plugins/commons-chunk-plugin/#extra-async-commons-chunk
  // new webpack.optimize.CommonsChunkPlugin({
  //   name: 'app',
  //   async: 'vendor-async',
  //   children: true,
  //   minChunks: 3,
  // }),
];

升级 html-webpack-plugin

"html-webpack-plugin": "^2.30.1" -> "html-webpack-plugin": "^4.3.0"

// https://stackoverflow.com/questions/49942558/deprecationwarning-tapable-plugin-is-deprecated-use-new-api-on-hooks-instea
// error
Tapable.apply is deprecated. Call apply on the plugin directly instead

yarn add -D html-webpack-plugin@latest

移除 extract-text-webpack-plugin，引入 mini-css-extract-plugin 并配置 css-loader

// const ExtractTextPlugin = require('extract-text-webpack-plugin');
// plugins:[
// extract css into its own file
// 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,
// }),
// ]

// extract: true
// if (options.extract) {
//   return ExtractTextPlugin.extract({
//     use: loaders,
//     fallback: 'vue-style-loader',
//   });
// }

yarn add -D mini-css-extract-plugin

// webpack.prod.conf.js
const MiniCssExtractPlugin = require("mini-css-extract-plugin");
plugins: [
    new MiniCssExtractPlugin(filename: utils.assetsPath('css/[name].[contenthash].css'))
];

// webpack.base.conf.js
module.exports = {
  module: {
    rules: [
      {
        test: /\.(sa|sc|c)ss$/,
        use: [
          {
            loader: MiniCssExtractPlugin.loader,
            options: {
              hmr: process.env.NODE_ENV === "development",
            },
          },
          "css-loader",
          "postcss-loader",
          "sass-loader",
        ],
      },
    ],
  },
};

配置 mode 属性

The 'mode' option has not been set, webpack will fallback to 'production' for this value. Set 'mode' option to 'development' or 'production' to enable defaults for each environment.

mode: "production";

升级 vue-loader

"vue-loader": "^13.3.0" -> "vue-loader": "14.2.2"

TypeError: Cannot read property ' vueOptions' of undefined

yarn add -D vue-loader@latest

vue-loader was used without the corresponding plugin. Make sure to include VueLoaderPlugin in your webpack config

// https://github.com/symfony/webpack-encore/issues/311
You probably use vue-loader v15 which was released yesterday and introduces a lot of changes compared to v14. One of these changes is that you have to use an extra plugin: VueLoaderPlugin (that's not handled yet by Encore).

In the meantime could you try removing your version of the vue-loader/VueLoaderPlugin and adding vue-loader@^14.2.2 instead?

yarn add -D [email protected]

(1:1) Unknown word

> 1 | // extracted by mini-css-extract-plugin

移除 postcss-loader。

// postcss: generateLoaders()

更新 HtmlWebpackPlugin 的 chunkSortMode

// https://www.cnblogs.com/wyliunan/p/10238717.html
Unhandled rejection Error: "dependency" is not a valid chunk sort mode

设置为 HtmlWebpackPlugin 的 chunkSortMode 为"auto": https://github.com/jantimon/h...

修复大小限制的报错

AssetsOverSizeLimitWarning: asset size limit: The following asset(s) exceed the recommended size limit (244 KiB 250000Byte).
This can impact web performance.

// webpack.config.js
module.exports = {
  performance: {
    hints: "warning",
    maxEntrypointSize: 5000 * 1024,
    maxAssetSize: 5000 * 1024,
  },
};

生成 manifest.js，生成 vendors.js

// https://webpack.js.org/configuration/optimization/#optimizationsplitchunks
// 生成manifest.js
optimization: {
    runtimeChunk: {
        name:'manifest'
    }
},

// https://webpack.js.org/plugins/split-chunks-plugin/#split-chunks-example-1
// 生成 vendors.js
optimization: {
  splitChunks: {
    cacheGroups: {
      commons: {
        test: /[\\/]node_modules[\\/]/,
        name: 'vendors',
        chunks: 'all',
      },
    },
  },
}

  output: {
-   chunkFilename: utils.assetsPath('js/[id].[chunkhash].js'),
+   chunkFilename: utils.assetsPath('js/[name].[chunkhash].js'),
  },

调试开发环境可用

Error: Cannot find module 'webpack/bin/config-yargs'

https://github.com/mzgoddard/jest-webpack/issues/27

"webpack-cli": "^2.1.3",
"webpack-dev-server": "^3.1.4"

mode: 'development',

// webpack Error: Callback was already called.
// https://github.com/webpack-contrib/mini-css-extract-plugin/issues/493
// webpack.dev.js
plugins:[
    new MiniCssExtractPlugin(),
]

// https://segmentfault.com/q/1010000012054980
// BaseClient.js:12 Uncaught TypeError: Cannot assign to read only property 'exports' of object '#