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。