vue-cli脚手架中webpack配置详解

什么是webpack

webpack是一个module bundler（模块打包工具），所谓的模块就是在平时的前端开发中，用到一些静态资源，如JavaScript、CSS、图片等文件，webpack就将这些静态资源文件称之为模块

webpack支持AMD和CommonJS，以及其他的一些模块系统，并且兼容多种JS书写规范，可以处理模块间的以来关系，所以具有更强大的JS模块化的功能，它能对静态资源进行统一的管理以及打包发布，在官网中用这张图片介绍：

它在很多地方都能替代Grunt和Gulp，因为它能够编译打包CSS，做CSS预处理，对JS的方言进行编译，打包图片，代码压缩等等。所以在我接触了webpack之后，就不太想用gulp了

为什么使用webpack

总结如下：
• 对 CommonJS 、AMD 、ES6的语法做了兼容；
• 对js、css、图片等资源文件都支持打包；
• 串联式模块加载器以及插件机制，让其具有更好的灵活性和扩展性，例如提供对CoffeeScript、ES6的支持；
• 有独立的配置文件webpack.config.js；
• 可以将代码切割成不同的chunk，实现按需加载，降低了初始化时间；
• 支持 SourceUrls 和 SourceMaps，易于调试；
• 具有强大的Plugin接口，大多是内部插件，使用起来比较灵活；
• webpack 使用异步 IO 并具有多级缓存。这使得 webpack 很快且在增量编译上更加快；
webpack主要是用于vue和React较多，其实它就非常像Browserify，但是将应用打包为多个文件。如果单页面应用有多个页面，那么用户只从下载对应页面的代码. 当他么访问到另一个页面, 他们不需要重新下载通用的代码。

基于本人项目使用

vue webpack的配置文件的基本目录结构如下：

config
├── dev.env.js //dev环境变量配置
├── index.js // dev和prod环境的一些基本配置
└── prod.env.js // prod环境变量配置
build
├── build.js // npm run build所执行的脚本
├── check-versions.js // 检查npm和node的版本
├── logo.png
├── utils.js // 一些工具方法，主要用于生成cssLoader和styleLoader配置
├── vue-loader.conf.js // vueloader的配置信息
├── webpack.base.conf.js // dev和prod的公共配置
├── webpack.dev.conf.js // dev环境的配置
└── webpack.prod.conf.js // prod环境的配置

Config文件夹下文件详解

• dev.env.js

config内的文件其实是服务于build的，大部分是定义一个变量export出去
use strict //[采用严格模式]
/**
* [webpack-merge提供了一个合并函数，它将数组和合并对象创建一个新对象
] 
*/
const merge = require('webpack-merge')
const prodEnv = require('./prod.env')

module.exports = merge(prodEnv, {
  NODE_ENV: '"development"'
})

• prod.env.js

当开发时调取dev.env.js的开发环境配置，发布时调用prod.env.js的生产环境配置
use strict
module.exports = {
  NODE_ENV: '"production"'
}

• index.js

const path = require('path')
module.exports = {
 /**
   * [开发环境配置]
   */
dev: {
    assetsSubDirectory: 'static',  // [子目录,一般存放css,js,image等文件]
assetsPublicPath: '/',  // [根目录]
/**
* [配置服务代理] 
*/
   proxyTable: {
      '/hcm': {
        target: 'https://127.0.0.1:8448',
        changeOrigin: true,
        secure: false
      },
      headers: {
        "Access-Control-Allow-Origin": "*",
        "Access-Control-Allow-Methods": "GET, POST, PUT, DELETE, PATCH, OPTIONS",
        "Access-Control-Allow-Headers": "X-Requested-With, content-type, Authorization"
      }
    },
    host: '127.0.0.1',  // [浏览器访问地址]
    port: 8083,  // [端口号设置，端口号占用出现问题可在此处修改]
    autoOpenBrowser: true, // [是否在编译（输入命令行npm run dev）后打开http://127.0.0.1:8083/页面]
    errorOverlay: true, // [浏览器错误提示]
    notifyOnErrors: true, // [跨平台错误提示]
    poll:false, // [使用文件系统(file system)获取文件改动的通知devServer.watchOptions] 
    useEslint: true, // [是否启用代码规范检查]
    showEslintErrorsInOverlay: false, // [是否展示eslint的错误提示]
    devtool: 'eval-source-map', // [增加调试，该属性为原始源代码]
    cacheBusting: true, // [使缓存失效]
    cssSourceMap: false // [代码压缩后进行调bug定位将非常困难，于是引入sourcemap记录压缩前后的位置信息记录，当产生错误时直接定位到未压缩前的位置，将大大的方便我们调试]
  },
/**
* [生产环境配置] 
*/
  build: {
  /**
* [index、login、license、forbidden、notfound、Internal.licenses编译后生成的位置和名字，根据需要改变后缀] 
*/
    index: path.resolve(__dirname, '../../hcm-modules/hcm-web/src/main/resources/META-INF/resources/index.html'),
    login: path.resolve(__dirname, '../../hcm-modules/hcm-web/src/main/resources/META-INF/resources/login.html'),
    license: path.resolve(__dirname, '../../hcm-modules/hcm-web/src/main/resources/META-INF/resources/license.html'),
    forbidden: path.resolve(__dirname, '../../hcm-modules/hcm-web/src/main/resources/META-INF/resources/error/403.html'),
    notfound: path.resolve(__dirname, '../../hcm-modules/hcm-web/src/main/resources/META-INF/resources/error/404.html'),
    internal: path.resolve(__dirname, '../../hcm-modules/hcm-web/src/main/resources/META-INF/resources/error/500.html'),
    licenses: path.resolve(__dirname, '../../hcm-modules/hcm-web/src/main/resources/META-INF/resources/docs/licenses.html'),
/**
* [编译后存放生成环境代码的位置] 
*/
    assetsRoot: path.resolve(__dirname, '../../hcm-modules/hcm-web/src/main/resources/META-INF/resources'),
    assetsSubDirectory: 'static', //js、css、images存放文件夹名
    assetsPublicPath: './', //发布的根目录，通常本地打包dist后打开文件会报错，此处修改为./。如果是上线的文件，可根据文件存放位置进行更改路径
    productionSourceMap: true,
    devtool: '#source-map',
    productionGzip: false, //unit的gzip命令用来压缩文件，gzip模式下需要压缩的文件的扩展名有js和css
    productionGzipExtensions: ['js', 'css'],
    bundleAnalyzerReport: process.env.npm_config_report //打包分析
  }
}

build文件夹下文件详解

• build.js

该文件作用，即构建生产版本。package.json中的scripts的build就是node build/build.js，输入命令行npm run build对该文件进行编译生成生产环境的代码。

require('./check-versions')() //check-versions：调用检查版本的文件。加（）代表直接调用该函数
process.env.NODE_ENV = 'production' //设置当前是生产环境
/**
*下面定义常量引入插件
*/
const ora = require('ora') //加载动画
const rm = require('rimraf') //删除文件
const path = require('path')
const chalk = require('chalk') //对文案输出的一个彩色设置
const webpack = require('webpack')
const config = require('../config') //默认读取下面的index.js文件
const webpackConfig = require('./webpack.prod.conf')
const spinner = ora('building for production...') //调用start的方法实现加载动画，优化用户体验
spinner.start()
//先删除dist文件再生成新文件，因为有时候会使用hash来命名，删除整个文件可避免冗余
rm(path.join(config.build.assetsRoot, config.build.assetsSubDirectory), err => {
  if (err) throw err
  webpack(webpackConfig, (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')
    if (stats.hasErrors()) {
      console.log(chalk.red('  Build failed with errors.\n'))
      process.exit(1)
    }
    console.log(chalk.cyan('  Build complete.\n'))
    console.log(chalk.yellow(
      '  Tip: built files are meant to be served over an HTTP server.\n' +
      '  Opening index.html over file:// won\'t work.\n'
    ))
  })
})

• check-versions.js

const chalk = require('chalk') 
const semver = require('semver') //对版本进行检查
const packageConfig = require('../package.json')
const shell = require('shelljs')
function exec (cmd) {
  //返回通过child_process模块的新建子进程，执行 Unix 系统命令后转成没有空格的字符串
  return require('child_process').execSync(cmd).toString().trim()
}
const versionRequirements = [
  {
    name: 'node',
    currentVersion: semver.clean(process.version), //使用semver格式化版本
    versionRequirement: packageConfig.engines.node //获取package.json中设置的node版本
  }
]
if (shell.which('npm')) {
  versionRequirements.push({
    name: 'npm',
    currentVersion: exec('npm --version'), // 自动调用npm --version命令，并且把参数返回给exec函数，从而获取纯净的版本号
    versionRequirement: packageConfig.engines.npm
  })
}
module.exports = function () {
  const warnings = []
  for (let i = 0; i < versionRequirements.length; i++) {
    const mod = versionRequirements[i]
    if (!semver.satisfies(mod.currentVersion, mod.versionRequirement)) {
      //上面这个判断就是如果版本号不符合package.json文件中指定的版本号，就执行下面错误提示的代码
warnings.push(mod.name + ': ' +
        chalk.red(mod.currentVersion) + ' should be ' +
        chalk.green(mod.versionRequirement)
      )
    }
  }
  if (warnings.length) {
    console.log('')
    console.log(chalk.yellow('To use this template, you must update following to modules:'))
    console.log()
    for (let i = 0; i < warnings.length; i++) {
      const warning = warnings[i]
      console.log('  ' + warning)
    }
    console.log()
    process.exit(1)
  }
}

• utils.js

const path = require('path')
const config = require('../config')
const ExtractTextPlugin = require('extract-text-webpack-plugin')
const packageConfig = require('../package.json')
exports.assetsPath = function (_path) {
  const assetsSubDirectory = process.env.NODE_ENV === 'production'
    ? config.build.assetsSubDirectory
    : config.dev.assetsSubDirectory
  return path.posix.join(assetsSubDirectory, _path)
}
exports.cssLoaders = function (options) {
  options = options || {}
//使用了css-loader和postcssLoader，通过options.usePostCSS属性来判断是否使用postcssLoader中压缩等方法

  const cssLoader = {
    loader: 'css-loader',
    options: {
      sourceMap: options.sourceMap
    }
  }
  const postcssLoader = {
    loader: 'postcss-loader',
    options: {
      sourceMap: options.sourceMap
    }
  }
  // generate loader string to be used with extract text plugin
  function generateLoaders (loader, loaderOptions) {
    const loaders = options.usePostCSS ? [cssLoader, postcssLoader] : [cssLoader]
    if (loader) {
      loaders.push({
        loader: loader + '-loader',
    //Object.assign是es6语法的浅复制，后两者合并后复制完成赋值
        options: Object.assign({}, loaderOptions, {
          sourceMap: options.sourceMap
        })
      })
    }
    // Extract CSS when that option is specified
    // (which is the case during production build)
if (options.extract) {
//ExtractTextPlugin可提取出文本，代表首先使用上面处理的loaders，当未能正确引入时使用vue-style-loader
      return ExtractTextPlugin.extract({
        use: loaders,
        fallback: 'vue-style-loader',
        publicPath: '../../'
      })
} else {
//返回vue-style-loader连接loaders的最终值
      return ['vue-style-loader'].concat(loaders)
    }
  }
  // https://vue-loader.vuejs.org/en/configurations/extract-css.html
  return {
    css: generateLoaders(),//需要css-loader 和 vue-style-loader
    postcss: generateLoaders(),//需要css-loader和postcssLoader  和 vue-style-loader
    less: generateLoaders('less'), //需要less-loader 和 vue-style-loader
    sass: generateLoaders('sass', { indentedSyntax: true }), //需要sass-loader 和 vue-style-loader
    scss: generateLoaders('sass'), //需要sass-loader 和 vue-style-loader
    stylus: generateLoaders('stylus'), //需要stylus-loader 和 vue-style-loader
    styl: generateLoaders('stylus') //需要stylus-loader 和 vue-style-loader
  }
}
// Generate loaders for standalone style files (outside of .vue)
exports.styleLoaders = function (options) {
  const output = []
  const loaders = exports.cssLoaders(options)
//将各种css,less,sass等综合在一起得出结果输出output
  for (const extension in loaders) {
    const loader = loaders[extension]
    output.push({
      test: new RegExp('\\.' + extension + '$'),
      use: loader
    })
  }
  return output
}
exports.createNotifierCallback = () => {
//发送跨平台通知系统
  const notifier = require('node-notifier')
  return (severity, errors) => {
if (severity !== 'error') return
//当报错时输出错误信息的标题，错误信息详情，副标题以及图标
    const error = errors[0]
    const filename = error.file && error.file.split('!').pop()
    notifier.notify({
      title: packageConfig.name,
      message: severity + ': ' + error.name,
      subtitle: filename || '',
      icon: path.join(__dirname, 'logo.png')
    })
  }
}

• vue-loader.conf.js

const utils = require('./utils')
const config = require('../config')
const isProduction = process.env.NODE_ENV === 'production'
const sourceMapEnabled = isProduction
  ? config.build.productionSourceMap
  : config.dev.cssSourceMap
//处理项目中的css文件，生产环境和测试环境默认是打开sourceMap，而extract中的提取样式到单独文件只有在生产环境中才需要
module.exports = {
  loaders: utils.cssLoaders({
    sourceMap: sourceMapEnabled,
    extract: isProduction
  }),
  cssSourceMap: sourceMapEnabled,
  cacheBusting: config.dev.cacheBusting,
// 在模版编译过程中，编译器可以将某些属性，如 src 路径，转换为require调用，以便目标资源可以由 webpack 处理
  transformToRequire: {
    video: ['src', 'poster'],
    source: 'src',
    img: 'src',
    image: 'xlink:href'
  }
}

• webpack.base.conf.js

const path = require('path')
const utils = require('./utils')
/**
* [引入index.js文件路径] 
*/
const config = require('../config')
const vueLoaderConfig = require('./vue-loader.conf')

/**
  * [获取文件路径]
  * @param dir [文件名称]
  *_dirname为当前模块文件所在目录的绝对路径* 
  *@return 文件绝对路径
*/
function resolve (dir) {
  return path.join(__dirname, '..', dir)
}
const createLintingRule = () => ({
  test: /\.(js|vue)$/,
  loader: 'eslint-loader',
  enforce: 'pre',
  include: [resolve('src'), resolve('test')],
  options: {
    formatter: require('eslint-friendly-formatter'),
    emitWarning: !config.dev.showEslintErrorsInOverlay
  }
})

module.exports = {
  context: path.resolve(__dirname, '../'),
    /**
       * [入口文件配置]
      */
  entry: {
/**
       * [入口文件路径, babel-polyfill是对es6语法的支持]
      */
    app: ['babel-polyfill', './src/main.js'],
    login: ['babel-polyfill', './src/loginMain.js'],
    license: ['babel-polyfill', './src/licenseMain.js']
  },
/**
   * [文件导出配置]
*/
  output: {
    path: config.build.assetsRoot,
    filename: '[name].js',
    publicPath: process.env.NODE_ENV === 'production'
      ? config.build.assetsPublicPath
      : config.dev.assetsPublicPath //公共存放路径
  },
  resolve: {
    /**
       * [extensions: 配置文件的扩展名,当在important文件时,不用需要添加扩展名]
      */
extensions: ['.js', '.vue', '.json'],
/**
       * [alias 给路径定义别名]
*/
    alias: {
      'vue$': 'vue/dist/vue.esm.js',
      '@': resolve('src')
    }
  },
/**
*使用插件配置相应文件的处理方法
*/
  module: {
rules: [
      ...(config.dev.useEslint ? [createLintingRule()] : []),
/**
     * [使用vue-loader将vue文件转化成js的模块]
*/
      {
        test: /\.vue$/,
        loader: 'vue-loader',
        options: vueLoaderConfig
      },
/**
       * [通过babel-loader将js进行编译成es5/es6 文件]
*/
      {
        test: /\.js$/,
        loader: 'babel-loader',
        include: [resolve('src'), resolve('test')]
      },
/**
     * [图片、音像、字体都使用url-loader进行处理，超过10000会编译成base64]
*/
      {
        test: /\.(png|jpe?g|gif|svg)(\?.*)?$/,
        loader: 'url-loader',
        options: {
          limit: 10000,
          name: utils.assetsPath('img/[name].[hash:7].[ext]')
        }
      },
      {
        test: /\.(mp4|webm|ogg|mp3|wav|flac|aac)(\?.*)?$/,
        loader: 'url-loader',
        options: {
          limit: 10000,
          name: utils.assetsPath('media/[name].[hash:7].[ext]')
        }
      },
      {
        test: /\.(woff2?|eot|ttf|otf)(\?.*)?$/,
        loader: 'url-loader',
        options: {
          limit: 10000,
          name: utils.assetsPath('fonts/[name].[hash:7].[ext]')
        }
      },
/**
       * [canvas 解析]
*/
      {
        test: path.resolve(`${resolve('src')}/lib/jtopo.js`),
        loader: ['exports-loader?window.JTopo', 'script-loader']
      }
    ]
  },
//以下选项是Node.js全局变量或模块，这里主要是防止webpack注入一些Node.js的东西到vue中 
  node: {
    setImmediate: false,
    dgram: 'empty',
    fs: 'empty',
    net: 'empty',                                                      
    tls: 'empty',
    child_process: 'empty'
  }
}

• webpack.dev.conf.js

const path = require('path')
const utils = require('./utils')
const webpack = require('webpack')
const config = require('../config')
//通过webpack-merge实现webpack.dev.conf.js对wepack.base.config.js的继承
const merge = require('webpack-merge')
const baseWebpackConfig = require('./webpack.base.conf')
const HtmlWebpackPlugin = require('html-webpack-plugin')
//美化webpack的错误信息和日志的插件
const FriendlyErrorsPlugin = require('friendly-errors-webpack-plugin')
// 查看空闲端口位置，默认情况下搜索8000这个端口
const portfinder = require('portfinder')
// processs为node的一个全局对象获取当前程序的环境变量，即host
const HOST = process.env.HOST
const PORT = process.env.PORT && Number(process.env.PORT)
function resolveApp(relativePath) {
  return path.resolve(relativePath);
}
const devWebpackConfig = merge(baseWebpackConfig, {
  module: {
//规则是工具utils中处理出来的styleLoaders，生成了css，less,postcss等规则
    rules: utils.styleLoaders({ sourceMap: config.dev.cssSourceMap, usePostCSS: true })
  },
// 增强调试
  devtool: config.dev.devtool,
// 此处的配置都是在config的index.js中设定好了
  devServer: {
//控制台显示的选项有none, error, warning 或者 info
clientLogLevel: 'warning',
//使用 HTML5 History API
historyApiFallback: true,
hot: true, //热加载
compress: true, //压缩
    host: HOST || config.dev.host,
port: PORT || config.dev.port,
open: config.dev.autoOpenBrowser,  //调试时自动打开浏览器
    overlay: config.dev.errorOverlay
      ? { warnings: false, errors: true }
      : false,
    publicPath: config.dev.assetsPublicPath,
proxy: config.dev.proxyTable,//接口代理
quiet: true, //控制台是否禁止打印警告和错误,若用FriendlyErrorsPlugin 此处为 true    watchOptions: {
      poll: config.dev.poll, // 文件系统检测改动
    }
  },
  plugins: [
    new webpack.DefinePlugin({
      'process.env': require('../config/dev.env')
    }),
new webpack.HotModuleReplacementPlugin(),//模块热替换插件，修改模块时不需要刷新页面
new webpack.NamedModulesPlugin(), // 显示文件的正确名字
new webpack.NoEmitOnErrorsPlugin(), //当webpack编译错误的时候，来中端打包进程，防止错误代码打包到文件中
// https://github.com/ampedandwired/html-webpack-plugin
// 该插件可自动生成一个 html5 文件或使用模板文件将编译好的代码注入进去 
new HtmlWebpackPlugin({
      filename: 'index.html',
      template: 'index.html',
      inject: true,
      chunks: ['app']
    }),
    new HtmlWebpackPlugin({
      filename: 'login.html',
      template: 'login.html',
      inject: true,
      chunks: ['login']
    }),
    new HtmlWebpackPlugin({
      filename: 'license.html',
      template: 'license.html',
      inject: true,
      chunks: ['license']
    }),
    new HtmlWebpackPlugin({
      filename: 'licenses.html',
      template: 'licenses.html',
      inject: true,
      chunks: []
    }),
    new HtmlWebpackPlugin({
      filename: '404.html',
      template: path.resolve(__dirname, '../errors/404.html'),
      favicon: resolveApp('favicon.ico'),
      inject: true,
      chunks: []
    }),
    new HtmlWebpackPlugin({
      filename: '403.html',
      template: path.resolve(__dirname, '../errors/403.html'),
      favicon: resolveApp('favicon.ico'),
      inject: true,
      chunks: []
    }),
    new HtmlWebpackPlugin({
      filename: '500.html',
      template: path.resolve(__dirname, '../errors/500.html'),
      favicon: resolveApp('favicon.ico'),
      inject: true,
      chunks: []
    })
  ]
})

module.exports = new Promise((resolve, reject) => {
  portfinder.basePort = process.env.PORT || config.dev.port
//查找端口号
  portfinder.getPort((err, port) => {
    if (err) {
      reject(err)
} else {
//端口被占用时就重新设置evn和devServer的端口
      process.env.PORT = port
      // add port to devServer config
      devWebpackConfig.devServer.port = port
//友好地输出信息
      devWebpackConfig.plugins.push(new FriendlyErrorsPlugin({
        compilationSuccessInfo: {
          messages: [`Your application is running here: http://${devWebpackConfig.devServer.host}:${port}`],
        },
        onErrors: config.dev.notifyOnErrors
        ? utils.createNotifierCallback()
        : undefined
      }))
      resolve(devWebpackConfig)
    }
  })
})

• webpack.prod.conf.js

const path = require('path')
const utils = require('./utils')
const webpack = require('webpack')
const config = require('../config')
const merge = require('webpack-merge')
const baseWebpackConfig = require('./webpack.base.conf')
const CopyWebpackPlugin = require('copy-webpack-plugin')
const HtmlWebpackPlugin = require('html-webpack-plugin')
const ExtractTextPlugin = require('extract-text-webpack-plugin')
const OptimizeCSSPlugin = require('optimize-css-assets-webpack-plugin')
const UglifyJsPlugin = require('uglifyjs-webpack-plugin')

const env = require('../config/prod.env')
function resolveApp(relativePath) {
  return path.resolve(relativePath);
}
const webpackConfig = merge(baseWebpackConfig, {
  module: {
    rules: utils.styleLoaders({
      sourceMap: config.build.productionSourceMap,//开启调试的模式。默认为true
      extract: true,
      usePostCSS: true
    })
  },
  devtool: config.build.productionSourceMap ? config.build.devtool : false,
  output: {
    path: config.build.assetsRoot,
    filename: utils.assetsPath('js/[name].[chunkhash].js'),
    chunkFilename: utils.assetsPath('js/[id].[chunkhash].js')
  },
  plugins: [
    // http://vuejs.github.io/vue-loader/en/workflow/production.html
    new webpack.DefinePlugin({
      'process.env': env
    }),
    new UglifyJsPlugin({
      uglifyOptions: {
        compress: {
          warnings: false  //警告：true保留警告，false不保留
        }
      },
      sourceMap: config.build.productionSourceMap,
      parallel: true
    }),
// extract css into its own file
//抽取文本。比如打包之后的index页面有style插入，就是这个插件抽取出来的，减少请求
new ExtractTextPlugin({
      filename: utils.assetsPath('css/[name].[contenthash].css'),
      allChunks: true,
}),
//优化css的插件
    new OptimizeCSSPlugin({
      cssProcessorOptions: config.build.productionSourceMap
        ? { safe: true, map: { inline: false } }
        : { safe: true }
    }),
    //html打包
    new HtmlWebpackPlugin({
      filename: config.build.index,
      template: 'index.html',
      inject: true,
//压缩
      minify: {
        removeComments: true, //删除注释
        collapseWhitespace: true, //删除空格
        removeAttributeQuotes: true //删除属性的引号
      },
      chunks: ['vendor', 'manifest', 'app'],
      // necessary to consistently work with multiple chunks via CommonsChunkPlugin
      chunksSortMode: 'dependency'
    }),
    new HtmlWebpackPlugin({
      filename: config.build.login,
      template: 'login.html',
      inject: true,
      minify: {
        removeComments: true,
        collapseWhitespace: true,
        removeAttributeQuotes: true
      },
      chunks: ['vendor', 'manifest', 'login'],
      // necessary to consistently work with multiple chunks via CommonsChunkPlugin
      chunksSortMode: 'dependency'
    }),
    new HtmlWebpackPlugin({
      filename: config.build.license,
      template: 'license.html',
      inject: true,
      minify: {
        removeComments: true,
        collapseWhitespace: true,
        removeAttributeQuotes: true
      },
      chunks: ['vendor', 'manifest', 'license'],
      // necessary to consistently work with multiple chunks via CommonsChunkPlugin
      chunksSortMode: 'dependency'
    }),
    new HtmlWebpackPlugin({
      filename: config.build.notfound,
      template: path.resolve(__dirname, '../errors/404.html'),
      inject: true,
      favicon: resolveApp('favicon.ico'),
      minify: {
        removeComments: true,
        collapseWhitespace: true,
        removeAttributeQuotes: true
      },
      chunks: [],
      // necessary to consistently work with multiple chunks via CommonsChunkPlugin
      chunksSortMode: 'dependency'
    }),
    new HtmlWebpackPlugin({
      filename: config.build.forbidden,
      template: path.resolve(__dirname, '../errors/403.html'),
      inject: true,
      favicon: resolveApp('favicon.ico'),
      minify: {
        removeComments: true,
        collapseWhitespace: true,
        removeAttributeQuotes: true
      },
      chunks: [],
      // necessary to consistently work with multiple chunks via CommonsChunkPlugin
      chunksSortMode: 'dependency'
    }),
    new HtmlWebpackPlugin({
      filename: config.build.internal,
      template: path.resolve(__dirname, '../errors/500.html'),
      inject: true,
      favicon: resolveApp('favicon.ico'),
      minify: {
        removeComments: true,
        collapseWhitespace: true,
        removeAttributeQuotes: true
      },
      chunks: [],
      // necessary to consistently work with multiple chunks via CommonsChunkPlugin
      chunksSortMode: 'dependency'
    }),
    new HtmlWebpackPlugin({
      filename: config.build.licenses,
      template: 'licenses.html',
      inject: true,
      minify: {
        removeComments: true,
        collapseWhitespace: true,
        removeAttributeQuotes: true
      },
      chunks: [],
      // necessary to consistently work with multiple chunks via CommonsChunkPlugin
      chunksSortMode: 'dependency'
    }),
    // keep module.id stable when vender modules does not change
    new webpack.HashedModuleIdsPlugin(),
    // enable scope hoisting
new webpack.optimize.ModuleConcatenationPlugin(),
//抽取公共的模块, 提升你的代码在浏览器中的执行速度。
    new webpack.optimize.CommonsChunkPlugin({
      name: 'vendor',
      minChunks (module) {
        // any required modules inside node_modules are extracted to vendor
        return (
          module.resource &&
          /\.js$/.test(module.resource) &&
          module.resource.indexOf(
            path.join(__dirname, '../node_modules')
          ) === 0
        )
      }
    }),
    // 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
}),
// 预编译所有模块到一个闭包中， 
  new webpack.optimize.CommonsChunkPlugin({
      name: 'app',
      async: 'vendor-async',
      children: true,
      minChunks: 3
    }),
//复制，比如打包完之后需要把打包的文件复制到dist里面
    new CopyWebpackPlugin([
      {
        from: path.resolve(__dirname, '../static'),
        to: config.build.assetsSubDirectory,
        ignore: ['.*']
      }
    ])
  ]
})

if (config.build.productionGzip) {
  const CompressionWebpackPlugin = require('compression-webpack-plugin')

  webpackConfig.plugins.push(
    new CompressionWebpackPlugin({
      asset: '[path].gz[query]',
      algorithm: 'gzip',
      test: new RegExp(
        '\\.(' +
        config.build.productionGzipExtensions.join('|') +
        ')$'
      ),
      threshold: 10240,
      minRatio: 0.8
    })
  )
}
// 提供带 Content-Encoding 编码的压缩版的资源
if (config.build.bundleAnalyzerReport) {
  const BundleAnalyzerPlugin = require('webpack-bundle-analyzer').BundleAnalyzerPlugin
  webpackConfig.plugins.push(new BundleAnalyzerPlugin())
}
module.exports = webpackConfig