阅读webpack代码笔记：antd-layout的webpack.config.prod.js

'use strict';

const autoprefixer = require('autoprefixer');//自动补全css前缀
const path = require('path');
const webpack = require('webpack');
//自动生成带有入口文件引用的index.html
const HtmlWebpackPlugin = require('html-webpack-plugin');
//ExtractTextPlugin将所有的入口 chunk(entry chunks)中引用的 *.css，移动到独立分离的 CSS 文件
const ExtractTextPlugin = require('extract-text-webpack-plugin');
//ManifestPlugin用于生成manifest.json
const ManifestPlugin = require('webpack-manifest-plugin');
//InterpolateHtmlPlugin:和HtmlWebpackPlugin串行使用，允许在index.html中添加变量
const InterpolateHtmlPlugin = require('react-dev-utils/InterpolateHtmlPlugin');
//用于使用service worker来缓存外部项目依赖项。 它将使用sw-precache生成service worker文件并将其添加到您的构建目录
const SWPrecacheWebpackPlugin = require('sw-precache-webpack-plugin');
const eslintFormatter = require('react-dev-utils/eslintFormatter');
const ModuleScopePlugin = require('react-dev-utils/ModuleScopePlugin');
const paths = require('./paths'); //获取paths对象
const getClientEnvironment = require('./env');

// Webpack uses `publicPath` to determine where the app is being served from.
// It requires a trailing slash, or the file assets will get an incorrect path.
const publicPath = paths.servedPath; //package.json所在的路径
// Some apps do not use client-side routing with pushState.
// For these, "homepage" can be set to "." to enable relative asset paths.
const shouldUseRelativeAssetPaths = publicPath === './';
// Source maps are resource heavy and can cause out of memory issue for large source files.
const shouldUseSourceMap = process.env.GENERATE_SOURCEMAP !== 'false';
// `publicUrl` is just like `publicPath`, but we will provide it to our app
// as %PUBLIC_URL% in `index.html` and `process.env.PUBLIC_URL` in JavaScript.
// Omit trailing slash as %PUBLIC_URL%/xyz looks better than %PUBLIC_URL%xyz.
const publicUrl = publicPath.slice(0, -1);
// Get environment variables to inject into our app.
const env = getClientEnvironment(publicUrl);

// Assert this just to be safe.
// Development builds of React are slow and not intended for production.
if (env.stringified['process.env'].NODE_ENV !== '"production"') {
    throw new Error('Production builds must have NODE_ENV=production.');
}

// Note: defined here because it will be used more than once.
const cssFilename = 'static/css/[name].[contenthash:8].css';

// ExtractTextPlugin expects the build output to be flat.
// (See https://github.com/webpack-contrib/extract-text-webpack-plugin/issues/27)
// However, our output is structured with css, js and media folders.
// To have this structure working with relative paths, we have to use custom options.
const extractTextPluginOptions = shouldUseRelativeAssetPaths
        ? // Making sure that the publicPath goes back to to build folder.
        { publicPath: Array(cssFilename.split('/').length).join('../') }
        : {};
 
// This is the production configuration.
// It compiles slowly and is focused on producing a fast and minimal bundle.
// The development configuration is different and lives in a separate file.
 

module.exports = {
    // Don't attempt to continue if there are any errors.
    bail: true,
    // We generate sourcemaps in production. This is slow but gives good results.
    // You can exclude the *.map files from the build during deployment.
    devtool: shouldUseSourceMap ? 'source-map' : false,
    // In production, we only want to load the polyfills and the app code.
    entry:{        // require.resolve('./polyfills'), 
        //paths.appIndexJs , 
        app:paths.appIndexJs , //src/index.js
        vendor:[ //把引用react的类提取出公共模块
          'react',
          'react-dom',
          'react-router'
        ],
        antd:[ //提取ant到公共模块
           'antd/lib/button',
           'antd/lib/icon'
         //'antd'
        ]
    },
    output: {
        // The build folder.
        path: paths.appBuild,
        // Generated JS file names (with nested folders).
        // There will be one main bundle, and one file per asynchronous chunk.
        // We don't currently advertise code splitting but Webpack supports it.
        filename: 'static/js/[name].[chunkhash:8].js',
        chunkFilename: 'static/js/[name].[chunkhash:8].chunk.js',
        // We inferred the "public path" (such as / or /my-project) from homepage.
        publicPath: publicPath,
        // Point sourcemap entries to original disk location (format as URL on Windows)
        devtoolModuleFilenameTemplate: info =>
                path
                        .relative(paths.appSrc, info.absoluteResourcePath)
                        .replace(/\\/g, '/'),
    },
    resolve: {//这些选项能设置模块如何被解析
        // This allows you to set a fallback for where Webpack should look for modules.
        // We placed these paths second because we want `node_modules` to "win"
        // if there are any conflicts. This matches Node resolution mechanism.
        // https://github.com/facebookincubator/create-react-app/issues/253
        //modules告诉 webpack 解析模块时应该搜索的目录
        modules: ['node_modules', paths.appNodeModules].concat(
                // It is guaranteed to exist because we tweak it in `env.js`
                process.env.NODE_PATH.split(path.delimiter).filter(Boolean)
        ),
        // These are the reasonable defaults supported by the Node ecosystem.
        // We also include JSX as a common component filename extension to support
        // some tools, although we do not recommend using it, see:
        // https://github.com/facebookincubator/create-react-app/issues/290
        // `web` extension prefixes have been added for better support
        // for React Native Web.
        //extensions:自动解析确定的扩展
        extensions: ['.web.js', '.mjs', '.js', '.json', '.web.jsx', '.jsx'],
        //alias: 创建 import 或 require 的别名
        alias: {

            // Support React Native Web
            // https://www.smashingmagazine.com/2016/08/a-glimpse-into-the-future-with-react-native-for-web/
            'react-native': 'react-native-web',
        },
        //plugin:应该使用的额外的解析插件列表
        plugins: [
            // Prevents users from importing files from outside of src/ (or node_modules/).
            // This often causes confusion because we only process files within src/ with babel.
            // To fix this, we prevent you from importing files out of src/ -- if you'd like to,
            // please link the files into your node_modules/ and let module-resolution kick in.
            // Make sure your source files are compiled, as they will not be processed in any way.
            new ModuleScopePlugin(paths.appSrc, [paths.appPackageJson]),
        ],
    },
    //module:这些选项决定了如何处理项目中的不同类型的模块
    module: {
        strictExportPresence: true,
        //每个规则可以分为三部分 - 条件(condition)，结果(result)和嵌套规则(nested rule)
        //创建模块时，匹配请求的规则数组。这些规则能够修改模块的创建方式。这些规则能够对模块(module)应用 loader，或者修改解析器(parser)。
        rules: [
            // TODO: Disable require.ensure as it's not a standard language feature.
            // We are waiting for https://github.com/facebookincubator/create-react-app/issues/2176.
            // { parser: { requireEnsure: false } },

            // First, run the linter.
            // It's important to do this before Babel processes the JS.
            {
                //test:匹配特定条件。一般是提供一个正则表达式或正则表达式的数组，但这不是强制的
                test: /\.(js|jsx|mjs)$/,
                enforce: 'pre',
                // use: [
                //     {
                //         options: {
                //             formatter: eslintFormatter,
                //             eslintPath: require.resolve('eslint'),

                //         },
                //         loader: require.resolve('eslint-loader'),
                //     },
                // ],
                //loader是文件预处理器
                //使用babel-loader加载js,jsx,mjs
                //babel-loader用来处理ES6语法，将其编译为浏览器可以执行的js语法
                loader: require.resolve('babel-loader'), //resolve返回绝对路径
                include: paths.appSrc,
            },
            {
                // "oneOf" will traverse all following loaders until one will
                // match the requirements. When no loader matches it will fall
                // back to the "file" loader at the end of the loader list.
                //oneOf:当规则匹配时，只使用第一个匹配规则
                oneOf: [
                    // "url" loader works just like "file" loader but it also embeds
                    // assets smaller than specified size as data URLs to avoid requests.
                    {
                        test: [/\.bmp$/, /\.gif$/, /\.jpe?g$/, /\.png$/],
                        loader: require.resolve('url-loader'),
                        options: {
                            limit: 10000,
                            name: 'static/media/[name].[hash:8].[ext]',
                        },
                    },
                    // Process JS with Babel.
                    {
                        test: /\.(js|jsx|mjs)$/,
                        include: paths.appSrc,
                        loader: require.resolve('babel-loader'),
                        // options: {
                        //     plugins: [
                        //         ['import', [{ libraryName: "antd", style: 'css' }]],
                        //     ],
                        //     compact: true,
                        // },
                    },
                    // The notation here is somewhat confusing.
                    // "postcss" loader applies autoprefixer to our CSS.
                    // "css" loader resolves paths in CSS and adds assets as dependencies.
                    // "style" loader normally turns CSS into JS modules injecting <style>,
                    // but unlike in development configuration, we do something different.
                    // `ExtractTextPlugin` first applies the "postcss" and "css" loaders
                    // (second argument), then grabs the result CSS and puts it into a
                    // separate file in our build process. This way we actually ship
                    // a single CSS file in production instead of JS code injecting <style>
                    // tags. If you use code splitting, however, any async bundles will still
                    // use the "style" loader inside the async code so CSS from them won't be
                    // in the main CSS file.
                    {//定义如何加载css，scss,如果需要解析less要再次配置
                        test: /\.(css|scss|styl)$/,
                        loader: ExtractTextPlugin.extract(
                                Object.assign(
                                        {
                                            fallback: {
                                                loader: require.resolve('style-loader'),
                                                options: {
                                                    hmr: false,
                                                },
                                            },
                                            use: [
                                                {
                                                    loader: require.resolve('css-loader'),
                                                    options: {
                                                        importLoaders: 1,
                                                        minimize: true,
                                                        sourceMap: shouldUseSourceMap,
                                                    },
                                                },
                                                {
                                                    loader: require.resolve('postcss-loader'),
                                                    options: {
                                                        // Necessary for external CSS imports to work
                                                        // https://github.com/facebookincubator/create-react-app/issues/2677
                                                        ident: 'postcss',
                                                        plugins: () => [
                                                            require('postcss-flexbugs-fixes'),
                                                            autoprefixer({
                                                                browsers: [
                                                                    '>1%',
                                                                    'last 4 versions',
                                                                    'Firefox ESR',
                                                                    'not ie < 9', // React doesn't support IE8 anyway
                                                                ],
                                                                flexbox: 'no-2009',
                                                            }),
                                                        ],
                                                    },
                                                },
                                                {
                                                    loader: require.resolve('sass-loader') // compiles Less to CSS
                                                },
                                                {
                                                    loader: require.resolve('stylus-loader') // compiles stylus to CSS
                                                }
                                            ],
                                        },
                                        extractTextPluginOptions
                                )
                        ),
                        // Note: this won't work without `new ExtractTextPlugin()` in `plugins`.
                    },
                    // "file" loader makes sure assets end up in the `build` folder.
                    // When you `import` an asset, you get its filename.
                    // This loader doesn't use a "test" so it will catch all modules
                    // that fall through the other loaders.
                    {
                        loader: require.resolve('file-loader'),
                        // Exclude `js` files to keep "css" loader working as it injects
                        // it's runtime that would otherwise processed through "file" loader.
                        // Also exclude `html` and `json` extensions so they get processed
                        // by webpacks internal loaders.
                        exclude: [/\.(js|jsx|mjs)$/, /\.html$/, /\.json$/],
                        options: {
                            name: 'static/media/[name].[hash:8].[ext]',
                        },
                    },
                    // ** STOP ** Are you adding a new loader?
                    // Make sure to add the new loader(s) before the "file" loader.
                ],
            },
        ],
    },
    //plugins定义使用的插件
    plugins: [
        new HelloWorldPlugin(),
        // Makes some environment variables available in index.html.
        // The public URL is available as %PUBLIC_URL% in index.html, e.g.:
        // <link rel="shortcut icon" href="%PUBLIC_URL%/favicon.ico">
        // In production, it will be an empty string unless you specify "homepage"
        // in `package.json`, in which case it will be the pathname of that URL.
        new InterpolateHtmlPlugin(env.raw),
        // Generates an `index.html` file with the <script> injected.
        new HtmlWebpackPlugin({
            inject: true,
            template: paths.appHtml,
            minify: {
                removeComments: true,
                collapseWhitespace: true,
                removeRedundantAttributes: true,
                useShortDoctype: true,
                removeEmptyAttributes: true,
                removeStyleLinkTypeAttributes: true,
                keepClosingSlash: true,
                minifyJS: true,
                minifyCSS: true,
                minifyURLs: true,
            },
        }),
        //CommonsChunkPlugin，用于抽离代码
        new webpack.optimize.CommonsChunkPlugin({
          names: ['antd', 'vendor'],
          minChunks: Infinity
        }),
        // Makes some environment variables available to the JS code, for example:
        // if (process.env.NODE_ENV === 'production') { ... }. See `./env.js`.
        // It is absolutely essential that NODE_ENV was set to production here.
        // Otherwise React will be compiled in the very slow development mode.
        new webpack.DefinePlugin(env.stringified),
        // Minify the code.
        new webpack.optimize.UglifyJsPlugin({
            compress: {
                warnings: false,
                // Disabled because of an issue with Uglify breaking seemingly valid code:
                // https://github.com/facebookincubator/create-react-app/issues/2376
                // Pending further investigation:
                // https://github.com/mishoo/UglifyJS2/issues/2011
                comparisons: false,
            },
            mangle: {
                safari10: true,
            },
            output: {
                comments: false,
                // Turned on because emoji and regex is not minified properly using default
                // https://github.com/facebookincubator/create-react-app/issues/2488
                ascii_only: true,
            },
            sourceMap: shouldUseSourceMap,
        }),
        // Note: this won't work without ExtractTextPlugin.extract(..) in `loaders`.
        new ExtractTextPlugin({
            filename: cssFilename,
        }),
        // Generate a manifest file which contains a mapping of all asset filenames
        // to their corresponding output file so that tools can pick it up without
        // having to parse `index.html`.
        new ManifestPlugin({
            fileName: 'asset-manifest.json',
        }),
        // Generate a service worker script that will precache, and keep up to date,
        // the HTML & assets that are part of the Webpack build.
        new SWPrecacheWebpackPlugin({
            // By default, a cache-busting query parameter is appended to requests
            // used to populate the caches, to ensure the responses are fresh.
            // If a URL is already hashed by Webpack, then there is no concern
            // about it being stale, and the cache-busting can be skipped.
            dontCacheBustUrlsMatching: /\.\w{8}\./,
            filename: 'service-worker.js',
            logger(message) {
                if (message.indexOf('Total precache size is') === 0) {
                    // This message occurs for every build and is a bit too noisy.
                    return;
                }
                if (message.indexOf('Skipping static resource') === 0) {
                    // This message obscures real errors so we ignore it.
                    // https://github.com/facebookincubator/create-react-app/issues/2612
                    return;
                }
                console.log(message);
            },
            minify: true,
            // For unknown URLs, fallback to the index page
            navigateFallback: publicUrl + '/index.html',
            // Ignores URLs starting from /__ (useful for Firebase):
            // https://github.com/facebookincubator/create-react-app/issues/2237#issuecomment-302693219
            navigateFallbackWhitelist: [/^(?!\/__).*/],
            // Don't precache sourcemaps (they're large) and build asset manifest:
            staticFileGlobsIgnorePatterns: [/\.map$/, /asset-manifest\.json$/],
        }),
        // Moment.js is an extremely popular library that bundles large locale files
        // by default due to how Webpack interprets its code. This is a practical
        // solution that requires the user to opt into importing specific locales.
        // https://github.com/jmblog/how-to-optimize-momentjs-with-webpack
        // You can remove this if you don't use Moment.js:
        new webpack.IgnorePlugin(/^\.\/locale$/, /moment$/),
    ],
    // Some libraries import Node modules but don't use them in the browser.
    // Tell Webpack to provide empty mocks for them so importing them works.
    node: {
        dgram: 'empty',
        fs: 'empty',
        net: 'empty',
        tls: 'empty',
        child_process: 'empty',
    },
};