Vue 打包优化之 externals 抽离公共的第三方库

使用 @vue/cli 脚手架构建的 Vue 全家桶项目，默认配置下，打包后会把 vue、vue-router、axios、vuex、element-ui、echarts 等公共库打包在一起，导致基础 chunk、vendor 包体积特别大，有时一个文件能达到 3-5MB，这会大大影响首次加载速度。因此需要抽离第三方公共库，配合使用 CDN 加速。

一、前言

项目依赖：

{
  "name": "vue-web",
  "version": "1.0.0",
  "private": true,
  "scripts": {
    "start": "vue-cli-service serve --mode local",
    "dev": "vue-cli-service serve --mode dev",
    "test": "vue-cli-service build --mode test",
    "serve": "vue-cli-service serve ",
    "s": "nodemon --watch vue.config.js --exec \"npm start\"",
    "build": "vue-cli-service build",
    "build:az": "vue-cli-service build --report",
    "git": "tive git -c tive.git.config.js",
    "lint": "vue-cli-service lint"
  },
  "dependencies": {
    "axios": "^0.18.1",
    "d3": "^6.7.0",
    "dagre-d3": "^0.6.4",
    "echarts": "^5.3.3",
    "element-ui": "^2.15.9",
    "v-clipboard": "^2.2.3",
    "vue": "^2.7.10",
    "vue-router": "^3.6.5",
    "vuex": "^3.6.2"
  },
  "devDependencies": {
    "@vue/cli-plugin-babel": "^3.12.1",
    "@vue/cli-plugin-eslint": "^3.12.1",
    "@vue/cli-service": "^3.12.1",
    "compression-webpack-plugin": "^3.0.0",
    "html-webpack-externals-plugin": "^3.8.0",
    "less": "^3.13.1",
    "less-loader": "^4.1.0",
    "msw": "^0.47.3",
    "msw-tools": "latest",
    "uglifyjs-webpack-plugin": "^2.2.0",
    "vue-template-compiler": "^2.7.10",
    "webpack-bundle-analyzer": "^4.7.0"
  },
  "eslintConfig": {
    "root": true,
    "env": {
      "node": true
    },
    "extends": [
      "plugin:vue/essential",
      "eslint:recommended"
    ],
    "rules": {},
    "parserOptions": {
      "parser": "babel-eslint"
    }
  },
  "postcss": {
    "plugins": {
      "autoprefixer": {}
    }
  },
  "browserslist": [
    "> 1%",
    "last 2 versions",
    "not dead",
    "not ie 11"
  ],
  "msw": {
    "workerDirectory": "public"
  }
}

案例：项目整体使用了 element-ui，其中后台服务消费监控可视化引入了 echarts，元数据表血缘关系图使用了 d3 和 dagre-d3，这几个库本身体积就不小，打包到一起后体积更大。

二、优化配置

1. 安装 html-webpack-externals-plugin

npm i -D html-webpack-externals-plugin

2. 配置 vue.config.js

const CompressionWebpackPlugin = require('compression-webpack-plugin')
const UglifyJsPlugin = require('uglifyjs-webpack-plugin')
const { BundleAnalyzerPlugin } = require('webpack-bundle-analyzer')
const HtmlWebpackExternalsPlugin = require('html-webpack-externals-plugin')

const isProduction = process.env.NODE_ENV === 'production'

module.exports = {
  publicPath: '/datalk/',
  assetsDir: 'static',
  lintOnSave: false,
  productionSourceMap: false,
  devServer: {
    headers: {
      'Access-Control-Allow-Origin': '*',
    },
    host: '0.0.0.0',
    port: 1024,
    disableHostCheck: true,
    proxy: {
      '/api': {
        target: 'https://tiven.cn/api',
        changeOrigin: true,
        ws: true,
        pathRewrite: {
          '^/api': '',
        },
      },
    },
  },
  configureWebpack: (config) => {
    if (isProduction) {
      config.performance = {
        hints: false,
      }
      config.plugins.push(
        new CompressionWebpackPlugin({
          algorithm: 'gzip',
          test: new RegExp('\\.(' + ['js', 'css'].join('|') + ')$'),
          threshold: 10240,
          minRatio: 0.8,
        })
      )
    } else {
      config.devtool = 'source-map'
    }
    
    // HtmlWebpackExternalsPlugin 关键配置 start
    config.plugins.push(
      new HtmlWebpackExternalsPlugin({
        externals: [
          {
            module: 'vue',
            entry: {
              path: 'dist/vue.min.js',
              type: 'js',
            },
            global: 'Vue',
          },
          {
            module: 'element-ui',
            entry: ['lib/index.js', 'lib/theme-chalk/index.css'],
            supplements: ['lib/theme-chalk/fonts/'],
            global: 'ELEMENT',
          },
          {
            module: 'axios',
            entry: {
              path: 'dist/axios.min.js',
            },
            global: 'axios',
          },
          {
            module: 'echarts',
            entry: {
              path: 'dist/echarts.min.js',
              attributes: {
                async: '',
                // defer: '',
              },
            },
            global: 'echarts',
            // append: true,
          },
          {
            module: 'd3',
            entry: {
              path: 'dist/d3.min.js',
              attributes: {
                async: '',
              },
            },
            global: 'd3',
          },
          {
            module: 'dagre-d3',
            entry: {
              path: 'dist/dagre-d3.min.js',
              attributes: {
                async: '',
              },
            },
            global: 'dagreD3',
          },
        ],
        // hash: true, // 设置后会在引用脚本时加上 hash，如下所示：
        // 
        // outputPath: 'static/lib', // 输出目录，默认为 vendor
        // publicPath: '/assets/', // 公共路径，默认为 /
      })
    )
    // HtmlWebpackExternalsPlugin 关键配置 end
    
    // 生成打包报告
    if (process.env.npm_lifecycle_event === 'build:az') {
      config.plugins.push(new BundleAnalyzerPlugin())
    }
  },
}

三、配置说明

• module ：库名，也就是 package.json 中的包依赖名。
• entry ：入口，有几种类型，string | array | object | array