2017-09-11更新:更新到webpack 2.6.1所对应的配置,完善部分代码注释。
由于最近在vue-cli生成的webpack模板项目的基础上写一个小东西,开发过程中需要改动到build和config里面一些相关的配置,所以刚好趁此机会将所有配置文件看一遍,理一理思路,也便于以后修改配置的时候不会“太折腾”。
一、文件结构
本文主要分析开发(dev)和构建(build)两个过程涉及到的文件,故下面文件结构仅列出相应的内容。
├─build│ ├─build.js│ ├─check-versions.js│ ├─dev-client.js│ ├─dev-server.js│ ├─utils.js│ ├─vue-loader.conf.js│ ├─webpack.base.conf.js│ ├─webpack.dev.conf.js│ ├─webpack.prod.conf.js│ └─webpack.test.conf.js├─config│ ├─dev.env.js│ ├─index.js│ ├─prod.env.js│ └─test.env.js├─...└─package.json
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二、指令分析
首先看package.json里面的scripts字段,
"scripts": { "dev": "node build/dev-server.js", "build": "node build/build.js", "unit": "cross-env BABEL_ENV=test karma start test/unit/karma.conf.js --single-run", "e2e": "node test/e2e/runner.js", "test": "npm run unit && npm run e2e", "lint": "eslint --ext .js,.vue src test/unit/specs test/e2e/specs" }
测试的东西先不看,直接看”dev”和”build”。运行”npm run dev”的时候执行的是build/dev-server.js文件,运行”npm run build”的时候执行的是build/build.js文件,我们可以从这两个文件开始进行代码阅读分析。
三、build文件夹分析
build/dev-server.js
首先来看执行”npm run dev”时候最先执行的build/dev-server.js文件。该文件主要完成下面几件事情:
- 检查node和npm的版本、引入相关插件和配置
- webpack对源码进行编译打包并返回compiler对象
- 创建express服务器
- 配置开发中间件(webpack-dev-middleware)和热重载中间件(webpack-hot-middleware)
- 挂载代理服务和中间件
- 配置静态资源
- 启动服务器监听特定端口(8080)
- 自动打开浏览器并打开特定网址(localhost:8080)
说明: express服务器提供静态文件服务,不过它还使用了http-proxy-middleware,一个http请求代理的中间件。前端开发过程中需要使用到后台的API的话,可以通过配置proxyTable来将相应的后台请求代理到专用的API服务器。
详情请看代码注释:
require('./check-versions')()var config = require('../config')if (!process.env.NODE_ENV) { process.env.NODE_ENV = JSON.parse(config.dev.env.NODE_ENV)}var opn = require('opn')var path = require('path')var express = require('express')var webpack = require('webpack')var proxyMiddleware = require('http-proxy-middleware')var webpackConfig = require('./webpack.dev.conf')var port = process.env.PORT || config.dev.portvar autoOpenBrowser = !!config.dev.autoOpenBrowservar proxyTable = config.dev.proxyTablevar app = express()var compiler = webpack(webpackConfig)var devMiddleware = require('webpack-dev-middleware')(compiler, { publicPath: webpackConfig.output.publicPath, quiet: true })var hotMiddleware = require('webpack-hot-middleware')(compiler, { log: false, heartbeat: 2000 })compiler.plugin('compilation', function (compilation) { compilation.plugin('html-webpack-plugin-after-emit', function (data, cb) { hotMiddleware.publish({ action: 'reload' }) cb() })})Object.keys(proxyTable).forEach(function (context) { var options = proxyTable[context] if (typeof options === 'string') { options = { target: options } } app.use(proxyMiddleware(options.filter || context, options))})app.use(require('connect-history-api-fallback')())app.use(devMiddleware)app.use(hotMiddleware)var staticPath = path.posix.join(config.dev.assetsPublicPath, config.dev.assetsSubDirectory)app.use(staticPath, express.static('./static'))var uri = 'http://localhost:' + portvar _resolvevar readyPromise = new Promise(resolve => { _resolve = resolve})console.log('> Starting dev server...')devMiddleware.waitUntilValid(() => { console.log('> Listening at ' + uri + '\n') if (autoOpenBrowser && process.env.NODE_ENV !== 'testing') { opn(uri) } _resolve()})var server = app.listen(port)module.exports = { ready: readyPromise, close: () => { server.close() }}
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build/webpack.base.conf.js
从代码中看到,dev-server使用的webpack配置来自build/webpack.dev.conf.js文件(测试环境下使用的是build/webpack.prod.conf.js,这里暂时不考虑测试环境)。而build/webpack.dev.conf.js中又引用了webpack.base.conf.js,所以这里我先分析webpack.base.conf.js。
webpack.base.conf.js主要完成了下面这些事情:
- 配置webpack编译入口
- 配置webpack输出路径和命名规则
- 配置模块resolve规则
- 配置不同类型模块的处理规则
说明: 这个配置里面只配置了.js、.vue、图片、字体等几类文件的处理规则,如果需要处理其他文件可以在module.rules里面另行配置。
具体请看代码注释:
var path = require('path')var fs = require('fs')var utils = require('./utils')var config = require('../config')var vueLoaderConfig = require('./vue-loader.conf')function resolve (dir) { return path.join(__dirname, '..', dir)}module.exports = { entry: { app: './src/main.js' }, output: { path: config.build.assetsRoot, filename: '[name].js', publicPath: process.env.NODE_ENV === 'production' ? config.build.assetsPublicPath : config.dev.assetsPublicPath }, resolve: { extensions: ['.js', '.vue', '.json'], alias: { 'vue$': 'vue/dist/vue.esm.js', '@': resolve('src'), }, symlinks: false }, module: { rules: [ { test: /\.(js|vue)$/, loader: 'eslint-loader', enforce: 'pre', include: [resolve('src'), resolve('test')], options: { formatter: require('eslint-friendly-formatter') } }, { test: /\.vue$/, loader: 'vue-loader', options: vueLoaderConfig }, { test: /\.js$/, loader: 'babel-loader', include: [resolve('src'), resolve('test')] }, { 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]') } } ] }}
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build/webpack.dev.conf.js
接下来看webpack.dev.conf.js,这里面在webpack.base.conf的基础上增加完善了开发环境下面的配置,主要包括下面几件事情:
- 将webpack的热重载客户端代码添加到每个entry对应的应用
- 合并基础的webpack配置
- 配置样式文件的处理规则,styleLoaders
- 配置Source Maps
- 配置webpack插件
详情请看代码注释:
var utils = require('./utils')var webpack = require('webpack')var config = require('../config')var merge = require('webpack-merge')var baseWebpackConfig = require('./webpack.base.conf')var HtmlWebpackPlugin = require('html-webpack-plugin')var FriendlyErrorsPlugin = require('friendly-errors-webpack-plugin')Object.keys(baseWebpackConfig.entry).forEach(function (name) { baseWebpackConfig.entry[name] = ['./build/dev-client'].concat(baseWebpackConfig.entry[name])})module.exports = merge(baseWebpackConfig, { module: { rules: utils.styleLoaders({ sourceMap: config.dev.cssSourceMap }) }, devtool: '#cheap-module-eval-source-map', plugins: [ new webpack.DefinePlugin({ 'process.env': config.dev.env }), new webpack.HotModuleReplacementPlugin(), new webpack.NoEmitOnErrorsPlugin(), new HtmlWebpackPlugin({ filename: 'index.html', template: 'index.html', inject: true }), new FriendlyErrorsPlugin() ]})
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build/utils.js
utils提供工具函数,包括生成处理各种样式语言的loader,获取资源文件存放路径的工具函数。
1. 计算资源文件存放路径
2. 生成cssLoaders用于加载.vue文件中的样式
3. 生成styleLoaders用于加载不在.vue文件中的单独存在的样式文件
var path = require('path')var config = require('../config')var ExtractTextPlugin = require('extract-text-webpack-plugin')exports.assetsPath = function (_path) { var assetsSubDirectory = process.env.NODE_ENV === 'production' ? config.build.assetsSubDirectory : config.dev.assetsSubDirectory return path.posix.join(assetsSubDirectory, _path)}exports.cssLoaders = function (options) { options = options || {} var cssLoader = { loader: 'css-loader', options: { minimize: process.env.NODE_ENV === 'production', sourceMap: options.sourceMap } } function generateLoaders (loader, loaderOptions) { var loaders = [cssLoader] if (loader) { loaders.push({ loader: loader + '-loader', options: Object.assign({}, loaderOptions, { sourceMap: options.sourceMap }) }) } if (options.extract) { return ExtractTextPlugin.extract({ use: loaders, fallback: 'vue-style-loader' }) } else { return ['vue-style-loader'].concat(loaders) } } return { css: generateLoaders(), postcss: generateLoaders(), less: generateLoaders('less'), sass: generateLoaders('sass', { indentedSyntax: true }), scss: generateLoaders('sass'), stylus: generateLoaders('stylus'), styl: generateLoaders('stylus') }}exports.styleLoaders = function (options) { var output = [] var loaders = exports.cssLoaders(options) for (var extension in loaders) { var loader = loaders[extension] output.push({ test: new RegExp('\\.' + extension + '$'), use: loader }) } return output}
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build/vue-loader.conf.js
vue-loader.conf的配置比较简单,详情请看代码注释:
var utils = require('./utils')var config = require('../config')var isProduction = process.env.NODE_ENV === 'production'module.exports = { loaders: utils.cssLoaders({ sourceMap: isProduction ? config.build.productionSourceMap : config.dev.cssSourceMap, extract: isProduction }), transformToRequire: { video: 'src', source: 'src', img: 'src', image: 'xlink:href' }}
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build/dev-client.js
dev-client.js里面主要写了浏览器端代码,用于实现webpack的热更新。
require('eventsource-polyfill')var hotClient = require('webpack-hot-middleware/client?noInfo=true&reload=true')hotClient.subscribe(function (event) { if (event.action === 'reload') { window.location.reload() }})
build/build.js
讲完了开发环境下的配置,下面开始来看构建环境下的配置。执行”npm run build”的时候首先执行的是build/build.js文件,build.js主要完成下面几件事:
- loading动画
- 删除目标文件夹
- 执行webpack构建
- 输出信息
说明: webpack编译之后会输出到配置里面指定的目标文件夹;删除目标文件夹之后再创建是为了去除旧的内容,以免产生不可预测的影响。
详情请看代码注释:
require('./check-versions')()process.env.NODE_ENV = 'production'var ora = require('ora')var rm = require('rimraf')var path = require('path')var chalk = require('chalk')var webpack = require('webpack')var config = require('../config')var webpackConfig = require('./webpack.prod.conf')var spinner = ora('building for production...')spinner.start() rm(path.join(config.build.assetsRoot, config.build.assetsSubDirectory), err => { if (err) throw err webpack(webpackConfig, function (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' )) })})
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build/webpack.prod.conf.js
构建的时候用到的webpack配置来自webpack.prod.conf.js,该配置同样是在webpack.base.conf基础上的进一步完善。主要完成下面几件事情:
- 合并基础的webpack配置
- 配置样式文件的处理规则,styleLoaders
- 配置webpack的输出
- 配置webpack插件
- gzip模式下的webpack插件配置
- webpack-bundle分析
说明: webpack插件里面多了丑化压缩代码以及抽离css文件等插件。
详情请看代码:
var path = require('path')var utils = require('./utils')var webpack = require('webpack')var config = require('../config')var merge = require('webpack-merge')var baseWebpackConfig = require('./webpack.base.conf')var CopyWebpackPlugin = require('copy-webpack-plugin')var HtmlWebpackPlugin = require('html-webpack-plugin')var ExtractTextPlugin = require('extract-text-webpack-plugin')var OptimizeCSSPlugin = require('optimize-css-assets-webpack-plugin')var env = config.build.envvar webpackConfig = merge(baseWebpackConfig, { module: { rules: utils.styleLoaders({ sourceMap: config.build.productionSourceMap, extract: true }) }, devtool: config.build.productionSourceMap ? '#source-map' : false, output: { path: config.build.assetsRoot, filename: utils.assetsPath('js/[name].[chunkhash].js'), chunkFilename: utils.assetsPath('js/[id].[chunkhash].js') }, plugins: [ new webpack.DefinePlugin({ 'process.env': env }), new webpack.optimize.UglifyJsPlugin({ compress: { warnings: false }, sourceMap: true }), new ExtractTextPlugin({ filename: utils.assetsPath('css/[name].[contenthash].css') }), new OptimizeCSSPlugin({ cssProcessorOptions: { safe: true } }), new HtmlWebpackPlugin({ filename: config.build.index, template: 'index.html', inject: true, minify: { removeComments: true, collapseWhitespace: true, removeAttributeQuotes: true }, chunksSortMode: 'dependency' }), new webpack.HashedModuleIdsPlugin(), new webpack.optimize.CommonsChunkPlugin({ name: 'vendor', minChunks: function (module, count) { return ( module.resource && /\.js$/.test(module.resource) && module.resource.indexOf( path.join(__dirname, '../node_modules') ) === 0 ) } }), new webpack.optimize.CommonsChunkPlugin({ name: 'manifest', chunks: ['vendor'] }), new CopyWebpackPlugin([ { from: path.resolve(__dirname, '../static'), to: config.build.assetsSubDirectory, ignore: ['.*'] } ]) ]})if (config.build.productionGzip) { var CompressionWebpackPlugin = require('compression-webpack-plugin') webpackConfig.plugins.push( new CompressionWebpackPlugin({ asset: '[path].gz[query]', algorithm: 'gzip', test: new RegExp( '\\.(' + config.build.productionGzipExtensions.join('|') + ')$' ), threshold: 10240, minRatio: 0.8 }) )}if (config.build.bundleAnalyzerReport) { var BundleAnalyzerPlugin = require('webpack-bundle-analyzer').BundleAnalyzerPlugin webpackConfig.plugins.push(new BundleAnalyzerPlugin())}module.exports = webpackConfig
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build/check-versions.js
最后是build文件夹下的check-version.js,它完成对node和npm的版本检测,下面是其代码注释:
var chalk = require('chalk')var semver = require('semver')var packageConfig = require('../package.json')var shell = require('shelljs')function exec (cmd) { return require('child_process').execSync(cmd).toString().trim()}var versionRequirements = [ { name: 'node', currentVersion: semver.clean(process.version), versionRequirement: packageConfig.engines.node }]if (shell.which('npm')) { versionRequirements.push({ name: 'npm', currentVersion: exec('npm --version'), versionRequirement: packageConfig.engines.npm })}module.exports = function () { var warnings = [] for (var i = 0; i < versionRequirements.length; i++) { var mod = versionRequirements[i] if (!semver.satisfies(mod.currentVersion, mod.versionRequirement)) { 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 (var i = 0; i < warnings.length; i++) { var warning = warnings[i] console.log(' ' + warning) } console.log() process.exit(1) }}
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四、config文件夹分析
config/index.js
config文件夹下最主要的文件就是index.js了,在这里面描述了开发和构建两种环境下的配置,前面的build文件夹下也有不少文件引用了index.js里面的配置。下面是代码注释:
var path = require('path')module.exports = { build: { env: require('./prod.env'), index: path.resolve(__dirname, '../dist/index.html'), assetsRoot: path.resolve(__dirname, '../dist'), assetsSubDirectory: 'static', assetsPublicPath: '/', productionSourceMap: true, productionGzip: false, productionGzipExtensions: ['js', 'css'], bundleAnalyzerReport: process.env.npm_config_report }, dev: { env: require('./dev.env'), port: 8080, autoOpenBrowser: true, assetsSubDirectory: 'static', assetsPublicPath: '/', proxyTable: {}, cssSourceMap: false }}
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config/dev.env.js、config/prod.env.js和config/test.env.js
这三个文件就简单设置了环境变量而已,没什么特别的。
五、总结
到这里对模板项目的build和config文件夹下面的内容已经基本了解,知道了在实际使用中根据自己的需求修改哪里的配置,例如,当我有需要配置代理的时候要在config/index.js里面的dev.proxyTable设置,当我修改了资源文件夹名称static同样需要在config/index.js里面设置。webpack的插件好多,在看代码的过程中遇到不认识的插件都是要去查看很多文档(github,npm或者博客),感觉实际过程中更改插件配置或者使用新插件也是需要费点心思钻文档和网上其他博客介绍。