webpack.prod.conf.js 生产环境配置文件：
‘use strict‘//js严格模式执行 const path = require(‘path‘)//这个模块是发布到NPM注册中心的NodeJS“路径”模块的精确副本 const utils = require(‘./utils‘)//utils.js文件 const webpack = require(‘webpack‘)//webpack模块 const config = require(‘../config‘)//config文件夹下的index.js 是不是很神奇？ const merge = require(‘webpack-merge‘)//合并数组、对象为一个新的对象的模块 const baseWebpackConfig = require(‘./webpack.base.conf‘)//webpack.base.conf.js const CopyWebpackPlugin = require(‘copy-webpack-plugin‘)//拷贝文件和文件夹模块 const htmlWebpackPlugin = require(‘html-webpack-plugin‘)//为html文件中引入的外部资源（比如script/link等）动态添加每次compile后的hash，保证文件名不重复的好处是防止引用缓存文件导致修改暂未生效；可生成创建html入口文件 const ExtractTextPlugin = require(‘extract-text-webpack-plugin‘)//抽离css样式，防止将样式打包到js中引起加载错乱 const OptimizeCSSPlugin = require(‘optimize-css-assets-webpack-plugin‘)//压缩css插件 const UglifyJsPlugin = require(‘uglifyjs-webpack-plugin‘)//压缩js代码。 const env = require(‘../config/prod.env‘)//设置为生产环境production //merge方法合并模块对象，在这个文件里是将基础配置webpack.base.conf.js和生产环境配置合并 const webpackConfig = merge(baseWebpackConfig, { module: {//模块配置 rules: utils.styleLoaders({//原版注释Generate loaders for standalone style files (outside of .vue)生成独立的样式文件装载机 sourceMap: config.build.productionSourceMap,//设置sourceMap extract: true,// usePostCSS: true }) }, devtool: config.build.productionSourceMap ? config.build.devtool : false,//指定是否使用sourceMap output: {//指定输出 path: config.build.assetsRoot, filename: utils.assetsPath(‘js/[name].[chunkhash].js‘),//编译输出的js文件存放在js文件夹下，命名规则添加hash计算 /** * 打包require.ensure方法中引入的模块，如果该方法中没有引入任何模块则不会生成任何chunk块文件 * * 比如在main.js文件中,require.ensure([],function(require){alert(11);}),这样不会打包块文件 * 只有这样才会打包生成块文件require.ensure([],function(require){alert(11);require(‘./greeter‘)}) * 或者这样require.ensure([‘./greeter‘],function(require){alert(11);}) * chunk的hash值只有在require.ensure中引入的模块发生变化,hash值才会改变 * 注意:对于不是在ensure方法中引入的模块,此属性不会生效,只能用CommonsChunkPlugin插件来提取 */ 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({//压缩js代码的插件 具体可以去npm查一下这个插件怎么用以及能设置哪些参数 uglifyOptions: { compress: { warnings: false } }, sourceMap: config.build.productionSourceMap,//是否生成sourceMap parallel: true }), // 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, }), // Compress extracted CSS. We are using this plugin so that possible // duplicated CSS from different components can be deduped. new OptimizeCSSPlugin({ cssProcessorOptions: config.build.productionSourceMap ? { safe: true, map: { inline: false } } : { safe: true } }), // generate dist index.html with correct asset hash for caching. // you can customize output by editing /index.html // see https://github.com/ampedandwired/html-webpack-plugin new HtmlWebpackPlugin({ filename: config.build.index, template: ‘index.html‘, inject: true, minify: { removeComments: true, collapseWhitespace: true, removeAttributeQuotes: true // more options: // https://github.com/kangax/html-minifier#options-quick-reference }, // necessary to consistently work with multiple chunks via CommonsChunkPlugin chunksSortMode: ‘dependency‘ }), // keep module.id stable when vendor modules does not change new webpack.HashedModuleIdsPlugin(), // enable scope hoisting new webpack.optimize.ModuleConcatenationPlugin(), // split vendor js into its own file new webpack.optimize.CommonsChunkPlugin({ name: ‘vendor‘, minChunks (module) { // any required modules inside node_modules are extracted to vendor return ( module.resource && /\.js$/.test(module.resource) && module.resource.indexOf( path.join(__dirname, ‘../node_modules‘) ) === 0 ) } }), // extract webpack runtime and module manifest to its own file in order to // prevent vendor hash from being updated whenever app bundle is updated new webpack.optimize.CommonsChunkPlugin({ name: ‘manifest‘, minChunks: Infinity }), // This instance extracts shared chunks from code splitted chunks and bundles them // in a separate chunk, similar to the vendor chunk // see: https://webpack.js.org/plugins/commons-chunk-plugin/#extra-async-commons-chunk new webpack.optimize.CommonsChunkPlugin({ name: ‘app‘, async: ‘vendor-async‘, children: true, minChunks: 3 }), // copy custom static assets new CopyWebpackPlugin([ { from: path.resolve(__dirname, ‘../static‘), to: config.build.assetsSubDirectory, ignore: [‘.*‘] } ]) ]//添加插件，是webpack功能更丰富 }) //是否允许压缩？ if (config.build.productionGzip) { const CompressionWebpackPlugin = require(‘compression-webpack-plugin‘) webpackConfig.plugins.push( new CompressionWebpackPlugin({ asset: ‘[path].gz[query]‘, algorithm: ‘gzip‘, test: new RegExp( ‘\\.(‘ + config.build.productionGzipExtensions.join(‘|‘) + ‘)$‘ ), threshold: 10240, minRatio: 0.8 }) ) } if (config.build.bundleAnalyzerReport) { const BundleAnalyzerPlugin = require(‘webpack-bundle-analyzer‘).BundleAnalyzerPlugin webpackConfig.plugins.push(new BundleAnalyzerPlugin()) } module.exports = webpackConfig
关于开发环境和生产环境的区别，引用一段官网长的解释。
开发环境(development)和生产环境(production)的构建目标差异很大。在开发环境中，我们需要具有强大的、具有实时重新加载(live reloading)或热模块替换(hot module replacement)能力的 source map 和 localhost server。而在生产环境中，我们的目标则转向于关注更小的 bundle，更轻量的 source map，以及更优化的资源，以改善加载时间。由于要遵循逻辑分离，我们通常建议为每个环境编写彼此独立的 webpack 配置。
虽然，以上我们将生产环境和开发环境做了略微区分，但是，请注意，我们还是会遵循不重复原则(Don‘t repeat yourself - DRY)，保留一个“通用”配置。为了将这些配置合并在一起，我们将使用一个名为 webpack-merge 的工具。