模块切割说明

              minSize: 30000,
              // maxSize: 500000, // 将大于maxSize的文件进行拆分，不设置则不拆分
              maxSize: 0, // 不拆分
              minChunks: 1,
              maxInitialRequests: 3,
              maxAsyncRequests: 5,
              name: true,
              cacheGroups: {
                vendors: { // 分割默认依赖，不打包在一起
                  test: /[\\/]node_modules[\\/]/,
                  priority: 10,
                  // https://github.com/facebook/create-react-app/issues/5372
                  // chunks: 'initial',
                  name(module) {
                    const packageName = module.context.match(/[\\/]node_modules[\\/](.*?)([\\/]|$)/)[1]
                    return `vendors.${packageName.replace('@', '')}`
                  }
                }
              }
              ////////////////////////
              chunks: 'all',
              cacheGroups: {
                libs: { // mainjs的依赖等
                  name: 'chunk-libs',
                  test: /[\\/]node_modules[\\/]/,
                  priority: 10,
                  chunks: 'initial' // only package third parties that are initially dependent
                },
                elementUI: {  // 需要提取的第三方包 // 权重要高于其他的
                  name: 'chunk-elementUI', // split elementUI into a single package
                  priority: 20, // the weight needs to be larger than libs and app or it will be packaged into libs or app
                  test: /[\\/]node_modules[\\/]_?element-ui(.*)/ // in order to adapt to cnpm
                },
                commons: { // 自定义分割的模块
                  name: 'chunk-commons',
                  test: resolve('src/components'), // can customize your rules
                  minChunks: 3, //  minimum common number
                  priority: 5,
                  reuseExistingChunk: true
                }
              }

const path = require('path');
const UglifyJsPlugin = require('uglifyjs-webpack-plugin') // 去掉注释
const CompressionWebpackPlugin = require('compression-webpack-plugin'); // 开启压缩
const { HashedModuleIdsPlugin } = require('webpack');
const CopyWebpackPlugin = require('copy-webpack-plugin');

function resolve(dir) {
    return path.join(__dirname, dir)
}

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

// cdn预加载使用
const externals = {
    'vue': 'Vue',
    'vue-router': 'VueRouter',
    'vuex': 'Vuex',
    'axios': 'axios',
    "element-ui": "ELEMENT"
}

const cdn = {
    // 开发环境
    dev: {
        css: [
            'https://unpkg.com/element-ui/lib/theme-chalk/index.css'
        ],
        js: []
    },
    // 生产环境
    build: {
        css: [
            'https://unpkg.com/element-ui/lib/theme-chalk/index.css'
        ],
        js: [
            'https://cdn.jsdelivr.net/npm/vue@2.5.17/dist/vue.min.js',
            'https://cdn.jsdelivr.net/npm/vue-router@3.0.1/dist/vue-router.min.js',
            'https://cdn.jsdelivr.net/npm/vuex@3.0.1/dist/vuex.min.js',
            'https://cdn.jsdelivr.net/npm/axios@0.18.0/dist/axios.min.js',
            'https://unpkg.com/element-ui/lib/index.js'
        ]
    }
}

module.exports = {
    lintOnSave: false, // 关闭eslint
    productionSourceMap: false,
    publicPath: './',
    outputDir: process.env.outputDir, // 生成文件的目录名称
    chainWebpack: config => {

        config.resolve.alias
            .set('@', resolve('src'))

        // 压缩图片
        config.module
            .rule('images')
            .test(/\.(png|jpe?g|gif|svg)(\?.*)?$/)
            .use('image-webpack-loader')
            .loader('image-webpack-loader')
            .options({ bypassOnDebug: true })

        // webpack 会默认给commonChunk打进chunk-vendors，所以需要对webpack的配置进行delete
        config.optimization.delete('splitChunks')

        config.plugin('html').tap(args => {
            if (process.env.NODE_ENV === 'production') {
                args[0].cdn = cdn.build
            }
            if (process.env.NODE_ENV === 'development') {
                args[0].cdn = cdn.dev
            }
            return args
        })

        config
            .plugin('webpack-bundle-analyzer')
            .use(require('webpack-bundle-analyzer').BundleAnalyzerPlugin)
    },

    configureWebpack: config => {
        const plugins = [];

        if (isProduction) {
            plugins.push(
                    new UglifyJsPlugin({
                        uglifyOptions: {
                            output: {
                                comments: false, // 去掉注释
                            },
                            warnings: false,
                            compress: {
                                drop_console: true,
                                drop_debugger: false,
                                pure_funcs: ['console.log'] //移除console
                            }
                        }
                    })
                )
                // 服务器也要相应开启gzip
            plugins.push(
                new CompressionWebpackPlugin({
                    algorithm: 'gzip',
                    test: /\.(js|css)$/, // 匹配文件名
                    threshold: 10000, // 对超过10k的数据压缩
                    deleteOriginalAssets: false, // 不删除源文件
                    minRatio: 0.8 // 压缩比
                })
            )

            // 用于根据模块的相对路径生成 hash 作为模块 id, 一般用于生产环境
            plugins.push(
                new HashedModuleIdsPlugin()
            )

            // 拷贝文件到指定目录，比如一些网站在根目录需要验证某些文本， from为文件的路径，还有一个to属性是输出的文件夹路径，不写则默认复制到打包后文件的根目录
            plugins.push(
                new CopyWebpackPlugin([{ from: './NLwdLAxhwv.txt' }])
            )

            // 开启分离js
            config.optimization = {
                runtimeChunk: 'single',
                splitChunks: {
                    chunks: 'all',
                    maxInitialRequests: Infinity,
                    minSize: 1000 * 60,
                    cacheGroups: {
                        vendor: {
                            test: /[\\/]node_modules[\\/]/,
                            name(module) {
                                // 排除node_modules 然后吧 @ 替换为空 ,考虑到服务器的兼容
                                const packageName = module.context.match(/[\\/]node_modules[\\/](.*?)([\\/]|$)/)[1]
                                return `npm.${packageName.replace('@', '')}`
                            }
                        }
                    }
                }
            };

            // 取消webpack警告的性能提示
            config.performance = {
                hints: 'warning',
                //入口起点的最大体积
                maxEntrypointSize: 1000 * 500,
                //生成文件的最大体积
                maxAssetSize: 1000 * 1000,
                //只给出 js 文件的性能提示
                assetFilter: function(assetFilename) {
                    return assetFilename.endsWith('.js');
                }
            }

            // 打包时npm包转CDN
            config.externals = externals;
        }

        return { plugins }
    },

    pluginOptions: {
        // 配置全局less
        'style-resources-loader': {
            preProcessor: 'less',
            patterns: [resolve('./src/style/theme.less')]
        }
    },
    css: {
        loaderOptions: {
            postcss: {
                plugins: [
                    require('postcss-pxtorem')({
                        rootValue: 75, // 换算的基数 1rem = 75px 这个是根据750px设计稿来的，如果是620 的就写 62
                        // 忽略转换正则匹配项。插件会转化所有的样式的px。比如引入了三方UI，也会被转化。目前我使用selectorBlackList字段，来过滤
                        //如果个别地方不想转化px。可以简单的使用大写的 PX 或 Px 。
                        selectorBlackList: ['weui', 'mu'], //
                        propList: ['*'], // 需要做转化处理的属性，如`hight`、`width`、`margin`等，`*`表示全部
                    })
                ]
            }
        }
    },
    devServer: {
        open: false, // 自动启动浏览器
        host: '0.0.0.0', // localhost
        port: 6060, // 端口号
        https: false,
        hotOnly: false, // 热更新
        proxy: {
            '^/sso': {
                target: process.env.VUE_APP_SSO, // 重写路径
                ws: true, //开启WebSocket
                secure: false, // 如果是https接口，需要配置这个参数
                changeOrigin: true
            }
        }
    }
}