• 从零开始搭建 creact-react-app 脚手架并配置less


    本次学习如何从零开始搭建一个react官方提供的脚手架并添加less配置项以及如何处理在搭建过程中出现的bug

    在此过程中默认使用yarn工具,

    使用官方提供的命令:(此过程可能会因为个人网速不同,创建的时间也会有所不一样)

    >yarn create react-app sugar  
    

      

    如图所示我们已经创建了一个基本的脚手架,但是由于在项目中我们会安装less插件,所以我们还需要将文件进行暴露,暴露文件的命令 yarn eject

    >yarn eject
    yarn run v1.17.3
    $ react-scripts eject
    NOTE: Create React App 2+ supports TypeScript, Sass, CSS Modules and more without ejecting: https://reactjs.org/blog/2018/10/01/create-react-app-v2.html
    
    ? Are you sure you want to eject? This action is permanent. (y/N)
    

      他会提示问你是否要暴露文件,这里可以直接回车,也可以选择y

    到这一步,我们使用yarn start 启动项目试试看

    >yarn start
    yarn run v1.17.3
    $ node scripts/start.js
    ? Something is already running on port 3000.
    
    Would you like to run the app on another port instead? Yes
    Starting the development server...
    Failed to compile.
    
    ./src/index.js
    Error: [BABEL] C:UsersSugarDesktop	estsugarsrcindex.js: Cannot find module '@babel/plugin-transform-react-jsx-source' (While processing: "C:\Users\Sugar\Desktop\test\sugar\node_modules\babel-preset-react-app\index.js$1")
        at Array.reduce (<anonymous>)
    

      此时你会发现他报错了!居然报错了,嗯  没错的,就是报错了,大概说的就是没找到哪个模块云云,百度找i到的解决方法有很多,其中我试过有效的有两种:

         1.去babel官方重新安装babel模块,但是这个方法我试过,不够粗暴。

      2.删掉node_module文件重新安装依赖。(此方法简单粗暴直接有效)。

     这里我选择删掉依赖模块重新安装,百试百灵,如果网速慢的话可以选择使用cnpm淘宝镜像安装。

    >yarn start
    yarn run v1.17.3
    $ node scripts/start.js
    ? Something is already running on port 3000.
    
    Would you like to run the app on another port instead? Yes
    Starting the development server...
    Compiled successfully!
    
    You can now view sugar in the browser.
    
      Local:            http://localhost:3001/
      On Your Network:  http://192.168.0.101:3001/
    
    Note that the development build is not optimized.
    To create a production build, use yarn build.
    

      等待安装以来完成后就可以启动项目,你会发现项目成功启动

      接下来我们安装less

    >yarn add less less-loader
    

      你以为这样就完成了吗?嗯  事情远远没有那么简单的,还需要在 config > webpack.config.js中进行一些配置项的修改。

    找到   // style files regexes  windows的大概在文件四十行,然后添加

    const lessRegex = /.less$/;
    const lessModuleRegex = /.module.less$/;
    

      

      找到

      并复制,就在它下面粘贴

       修改为

      最后找到114行左右添加

     这样就完成了我们的less的配置,接下来就是在文件中使用,我在src下创建了一个文件夹

    分别创建一个js和一个less,在js中引入

    最后 我们可以看到在浏览器中我们的样式已经发生了改变,证明我们的less是生效了

    最后就这样,如果对你有帮助,请给我点个赞

    webpack.config.js文件全文配置:

    'use strict';
    
    const fs = require('fs');
    const isWsl = require('is-wsl');
    const path = require('path');
    const webpack = require('webpack');
    const resolve = require('resolve');
    const PnpWebpackPlugin = require('pnp-webpack-plugin');
    const HtmlWebpackPlugin = require('html-webpack-plugin');
    const CaseSensitivePathsPlugin = require('case-sensitive-paths-webpack-plugin');
    const InlineChunkHtmlPlugin = require('react-dev-utils/InlineChunkHtmlPlugin');
    const TerserPlugin = require('terser-webpack-plugin');
    const MiniCssExtractPlugin = require('mini-css-extract-plugin');
    const OptimizeCSSAssetsPlugin = require('optimize-css-assets-webpack-plugin');
    const safePostCssParser = require('postcss-safe-parser');
    const ManifestPlugin = require('webpack-manifest-plugin');
    const InterpolateHtmlPlugin = require('react-dev-utils/InterpolateHtmlPlugin');
    const WorkboxWebpackPlugin = require('workbox-webpack-plugin');
    const WatchMissingNodeModulesPlugin = require('react-dev-utils/WatchMissingNodeModulesPlugin');
    const ModuleScopePlugin = require('react-dev-utils/ModuleScopePlugin');
    const getCSSModuleLocalIdent = require('react-dev-utils/getCSSModuleLocalIdent');
    const paths = require('./paths');
    const modules = require('./modules');
    const getClientEnvironment = require('./env');
    const ModuleNotFoundPlugin = require('react-dev-utils/ModuleNotFoundPlugin');
    const ForkTsCheckerWebpackPlugin = require('react-dev-utils/ForkTsCheckerWebpackPlugin');
    const typescriptFormatter = require('react-dev-utils/typescriptFormatter');
    
    const postcssNormalize = require('postcss-normalize');
    
    // Source maps are resource heavy and can cause out of memory issue for large source files.
    const shouldUseSourceMap = process.env.GENERATE_SOURCEMAP !== 'false';
    // Some apps do not need the benefits of saving a web request, so not inlining the chunk
    // makes for a smoother build process.
    const shouldInlineRuntimeChunk = process.env.INLINE_RUNTIME_CHUNK !== 'false';
    
    // Check if TypeScript is setup
    const useTypeScript = fs.existsSync(paths.appTsConfig);
    
    // style files regexes
    const cssRegex = /.css$/;
    const cssModuleRegex = /.module.css$/;
    const sassRegex = /.(scss|sass)$/;
    const sassModuleRegex = /.module.(scss|sass)$/;
    const lessRegex = /.less$/;
    const lessModuleRegex = /.module.less$/;
    // This is the production and development configuration.
    // It is focused on developer experience, fast rebuilds, and a minimal bundle.
    module.exports = function (webpackEnv) {
        const isEnvDevelopment = webpackEnv === 'development';
        const isEnvProduction = webpackEnv === 'production';
    
        // 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.
        // In development, we always serve from the root. This makes config easier.
        const publicPath = isEnvProduction
            ? paths.servedPath
            : isEnvDevelopment && '/';
        // 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 === './';
    
        // `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 = isEnvProduction
            ? publicPath.slice(0, -1)
            : isEnvDevelopment && '';
        // Get environment variables to inject into our app.
        const env = getClientEnvironment(publicUrl);
    
        // common function to get style loadersIcon
        const getStyleLoaders = (cssOptions, preProcessor) => {
            const loaders = [
                isEnvDevelopment && require.resolve('style-loader'),
                isEnvProduction && {
                    loader: MiniCssExtractPlugin.loader,
                    options: shouldUseRelativeAssetPaths ? {publicPath: '../../'} : {},
                },
                {
                    loader: require.resolve('css-loader'),
                    options: cssOptions,
                },
                {
                    // Options for PostCSS as we reference these options twice
                    // Adds vendor prefixing based on your specified browser support in
                    // package.json
                    loader: require.resolve('postcss-loader'),
                    options: {
                        // Necessary for external CSS imports to work
                        // https://github.com/facebook/create-react-app/issues/2677
                        ident: 'postcss',
                        plugins: () => [
                            require('postcss-flexbugs-fixes'),
                            require('postcss-preset-env')({
                                autoprefixer: {
                                    flexbox: 'no-2009',
                                },
                                stage: 3,
                            }),
                            // Adds PostCSS Normalize as the reset css with default options,
                            // so that it honors browserslist config in package.json
                            // which in turn let's users customize the target behavior as per their needs.
                            postcssNormalize(),
                        ],
                        sourceMap: isEnvProduction && shouldUseSourceMap,
                    },
                },
            ].filter(Boolean);
            if (preProcessor) {
                if (preProcessor === "less-loader") {
                    loaders.push({
                        loader: require.resolve(preProcessor),
                        options: {
                            sourceMap: isEnvProduction && shouldUseSourceMap,
                            javascriptEnabled: true,
                            modifyVars: {
                                "@primary-color": "red"
                            }
                        }
                    })
                } else {
                    loaders.push({
                        loader: require.resolve(preProcessor),
                        options: {
                            sourceMap: isEnvProduction && shouldUseSourceMap,
                        },
                    });
                }
            }
            return loaders;
        };
    
        return {
            mode: isEnvProduction ? 'production' : isEnvDevelopment && 'development',
            // Stop compilation early in production
            bail: isEnvProduction,
            devtool: isEnvProduction
                ? shouldUseSourceMap
                    ? 'source-map'
                    : false
                : isEnvDevelopment && 'cheap-module-source-map',
            // These are the "entry points" to our application.
            // This means they will be the "root" imports that are included in JS bundle.
            entry: [
                // Include an alternative client for WebpackDevServer. A client's job is to
                // connect to WebpackDevServer by a socket and get notified about changes.
                // When you save a file, the client will either apply hot updates (in case
                // of CSS changes), or refresh the page (in case of JS changes). When you
                // make a syntax error, this client will display a syntax error overlay.
                // Note: instead of the default WebpackDevServer client, we use a custom one
                // to bring better experience for Create React App users. You can replace
                // the line below with these two lines if you prefer the stock client:
                // require.resolve('webpack-dev-server/client') + '?/',
                // require.resolve('webpack/hot/dev-server'),
                isEnvDevelopment &&
                require.resolve('react-dev-utils/webpackHotDevClient'),
                // Finally, this is your app's code:
                paths.appIndexJs,
                // We include the app code last so that if there is a runtime error during
                // initialization, it doesn't blow up the WebpackDevServer client, and
                // changing JS code would still trigger a refresh.
            ].filter(Boolean),
            output: {
                // The build folder.
                path: isEnvProduction ? paths.appBuild : undefined,
                // Add /* filename */ comments to generated require()s in the output.
                pathinfo: isEnvDevelopment,
                // There will be one main bundle, and one file per asynchronous chunk.
                // In development, it does not produce real files.
                filename: isEnvProduction
                    ? 'static/js/[name].[contenthash:8].js'
                    : isEnvDevelopment && 'static/js/bundle.js',
                // TODO: remove this when upgrading to webpack 5
                futureEmitAssets: true,
                // There are also additional JS chunk files if you use code splitting.
                chunkFilename: isEnvProduction
                    ? 'static/js/[name].[contenthash:8].chunk.js'
                    : isEnvDevelopment && 'static/js/[name].chunk.js',
                // We inferred the "public path" (such as / or /my-project) from homepage.
                // We use "/" in development.
                publicPath: publicPath,
                // Point sourcemap entries to original disk location (format as URL on Windows)
                devtoolModuleFilenameTemplate: isEnvProduction
                    ? info =>
                        path
                            .relative(paths.appSrc, info.absoluteResourcePath)
                            .replace(/\/g, '/')
                    : isEnvDevelopment &&
                    (info => path.resolve(info.absoluteResourcePath).replace(/\/g, '/')),
            },
            optimization: {
                minimize: isEnvProduction,
                minimizer: [
                    // This is only used in production mode
                    new TerserPlugin({
                        terserOptions: {
                            parse: {
                                // we want terser to parse ecma 8 code. However, we don't want it
                                // to apply any minfication steps that turns valid ecma 5 code
                                // into invalid ecma 5 code. This is why the 'compress' and 'output'
                                // sections only apply transformations that are ecma 5 safe
                                // https://github.com/facebook/create-react-app/pull/4234
                                ecma: 8,
                            },
                            compress: {
                                ecma: 5,
                                warnings: false,
                                // Disabled because of an issue with Uglify breaking seemingly valid code:
                                // https://github.com/facebook/create-react-app/issues/2376
                                // Pending further investigation:
                                // https://github.com/mishoo/UglifyJS2/issues/2011
                                comparisons: false,
                                // Disabled because of an issue with Terser breaking valid code:
                                // https://github.com/facebook/create-react-app/issues/5250
                                // Pending futher investigation:
                                // https://github.com/terser-js/terser/issues/120
                                inline: 2,
                            },
                            mangle: {
                                safari10: true,
                            },
                            output: {
                                ecma: 5,
                                comments: false,
                                // Turned on because emoji and regex is not minified properly using default
                                // https://github.com/facebook/create-react-app/issues/2488
                                ascii_only: true,
                            },
                        },
                        // Use multi-process parallel running to improve the build speed
                        // Default number of concurrent runs: os.cpus().length - 1
                        // Disabled on WSL (Windows Subsystem for Linux) due to an issue with Terser
                        // https://github.com/webpack-contrib/terser-webpack-plugin/issues/21
                        parallel: !isWsl,
                        // Enable file caching
                        cache: true,
                        sourceMap: shouldUseSourceMap,
                    }),
                    // This is only used in production mode
                    new OptimizeCSSAssetsPlugin({
                        cssProcessorOptions: {
                            parser: safePostCssParser,
                            map: shouldUseSourceMap
                                ? {
                                    // `inline: false` forces the sourcemap to be output into a
                                    // separate file
                                    inline: false,
                                    // `annotation: true` appends the sourceMappingURL to the end of
                                    // the css file, helping the browser find the sourcemap
                                    annotation: true,
                                }
                                : false,
                        },
                    }),
                ],
                // Automatically split vendor and commons
                // https://twitter.com/wSokra/status/969633336732905474
                // https://medium.com/webpack/webpack-4-code-splitting-chunk-graph-and-the-splitchunks-optimization-be739a861366
                splitChunks: {
                    chunks: 'all',
                    name: false,
                },
                // Keep the runtime chunk separated to enable long term caching
                // https://twitter.com/wSokra/status/969679223278505985
                runtimeChunk: true,
            },
            resolve: {
                // 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/facebook/create-react-app/issues/253
                modules: ['node_modules', paths.appNodeModules].concat(
                    modules.additionalModulePaths || []
                ),
                // 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/facebook/create-react-app/issues/290
                // `web` extension prefixes have been added for better support
                // for React Native Web.
                extensions: paths.moduleFileExtensions
                    .map(ext => `.${ext}`)
                    .filter(ext => useTypeScript || !ext.includes('ts')),
                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',
                },
                plugins: [
                    // Adds support for installing with Plug'n'Play, leading to faster installs and adding
                    // guards against forgotten dependencies and such.
                    PnpWebpackPlugin,
                    // 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]),
                ],
            },
            resolveLoader: {
                plugins: [
                    // Also related to Plug'n'Play, but this time it tells Webpack to load its loaders
                    // from the current package.
                    PnpWebpackPlugin.moduleLoader(module),
                ],
            },
            module: {
                strictExportPresence: true,
                rules: [
                    // Disable require.ensure as it's not a standard language feature.
                    {parser: {requireEnsure: false}},
    
                    // First, run the linter.
                    // It's important to do this before Babel processes the JS.
                    {
                        test: /.(js|mjs|jsx|ts|tsx)$/,
                        enforce: 'pre',
                        use: [
                            {
                                options: {
                                    formatter: require.resolve('react-dev-utils/eslintFormatter'),
                                    eslintPath: require.resolve('eslint'),
    
                                },
                                loader: require.resolve('eslint-loader'),
                            },
                        ],
                        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: [
                            // "url" loader works like "file" loader except that it embeds assets
                            // smaller than specified limit in bytes as data URLs to avoid requests.
                            // A missing `test` is equivalent to a match.
                            {
                                test: [/.bmp$/, /.gif$/, /.jpe?g$/, /.png$/],
                                loader: require.resolve('url-loader'),
                                options: {
                                    limit: 10000,
                                    name: 'static/media/[name].[hash:8].[ext]',
                                },
                            },
                            // Process application JS with Babel.
                            // The preset includes JSX, Flow, TypeScript, and some ESnext features.
                            {
                                test: /.(js|mjs|jsx|ts|tsx)$/,
                                include: paths.appSrc,
                                loader: require.resolve('babel-loader'),
                                options: {
                                    customize: require.resolve(
                                        'babel-preset-react-app/webpack-overrides'
                                    ),
                                    plugins: [
                                        [
                                            require.resolve('babel-plugin-named-asset-import'),
                                            {
                                                loaderMap: {
                                                    svg: {
                                                        ReactComponent: '@svgr/webpack?-svgo,+ref![path]',
                                                    },
                                                },
                                            },
                                        ],
                                        // 按需引入less
                                        [
                                            'import', {
                                            libraryName: 'antd',
                                            style: true
                                        }
                                        ],
                                    ],
                                    // This is a feature of `babel-loader` for webpack (not Babel itself).
                                    // It enables caching results in ./node_modules/.cache/babel-loader/
                                    // directory for faster rebuilds.
                                    cacheDirectory: true,
                                    cacheCompression: isEnvProduction,
                                    compact: isEnvProduction,
                                },
                            },
                            // Process any JS outside of the app with Babel.
                            // Unlike the application JS, we only compile the standard ES features.
                            {
                                test: /.(js|mjs)$/,
                                exclude: /@babel(?:/|\{1,2})runtime/,
                                loader: require.resolve('babel-loader'),
                                options: {
                                    babelrc: false,
                                    configFile: false,
                                    compact: false,
                                    presets: [
                                        [
                                            require.resolve('babel-preset-react-app/dependencies'),
                                            {helpers: true},
                                        ],
                                    ],
                                    cacheDirectory: true,
                                    cacheCompression: isEnvProduction,
    
                                    // If an error happens in a package, it's possible to be
                                    // because it was compiled. Thus, we don't want the browser
                                    // debugger to show the original code. Instead, the code
                                    // being evaluated would be much more helpful.
                                    sourceMaps: false,
                                },
                            },
                            // "postcss" loader applies autoprefixer to our CSS.
                            // "css" loader resolves paths in CSS and adds assets as dependencies.
                            // "style" loader turns CSS into JS modules that inject <style> tags.
                            // In production, we use MiniCSSExtractPlugin to extract that CSS
                            // to a file, but in development "style" loader enables hot editing
                            // of CSS.
                            // By default we support CSS Modules with the extension .module.css
                            {
                                test: cssRegex,
                                exclude: cssModuleRegex,
                                use: getStyleLoaders({
                                    importLoaders: 1,
                                    sourceMap: isEnvProduction && shouldUseSourceMap,
                                }),
                                // Don't consider CSS imports dead code even if the
                                // containing package claims to have no side effects.
                                // Remove this when webpack adds a warning or an error for this.
                                // See https://github.com/webpack/webpack/issues/6571
                                sideEffects: true,
                            },
                            // Adds support for CSS Modules (https://github.com/css-modules/css-modules)
                            // using the extension .module.css
                            {
                                test: cssModuleRegex,
                                use: getStyleLoaders({
                                    importLoaders: 1,
                                    sourceMap: isEnvProduction && shouldUseSourceMap,
                                    modules: true,
                                    getLocalIdent: getCSSModuleLocalIdent,
                                }),
                            },
                            // Opt-in support for SASS (using .scss or .sass extensions).
                            // By default we support SASS Modules with the
                            // extensions .module.scss or .module.sass
                            {
                                test: sassRegex,
                                exclude: sassModuleRegex,
                                use: getStyleLoaders(
                                    {
                                        importLoaders: 2,
                                        sourceMap: isEnvProduction && shouldUseSourceMap,
                                    },
                                    'sass-loader'
                                ),
                                // Don't consider CSS imports dead code even if the
                                // containing package claims to have no side effects.
                                // Remove this when webpack adds a warning or an error for this.
                                // See https://github.com/webpack/webpack/issues/6571
                                sideEffects: true,
                            },
                            {
                                test: sassModuleRegex,
                                use: getStyleLoaders(
                                    {
                                        importLoaders: 2,
                                        sourceMap: isEnvProduction && shouldUseSourceMap,
                                        modules: true,
                                        getLocalIdent: getCSSModuleLocalIdent,
                                    },
                                    'sass-loader'
                                ),
                            },
    
                            // less
                            {
                                test: lessRegex,
                                exclude: lessModuleRegex,
                                use: getStyleLoaders(
                                    {
                                        importLoaders: 2,
                                        sourceMap: isEnvProduction && shouldUseSourceMap,
                                    },
                                    'less-loader'
                                ),
                                // Don't consider CSS imports dead code even if the
                                // containing package claims to have no side effects.
                                // Remove this when webpack adds a warning or an error for this.
                                // See https://github.com/webpack/webpack/issues/6571
                                sideEffects: true,
                            },
                            {
                                test: lessModuleRegex,
                                use: getStyleLoaders(
                                    {
                                        importLoaders: 2,
                                        sourceMap: isEnvProduction && shouldUseSourceMap,
                                        modules: true,
                                        getLocalIdent: getCSSModuleLocalIdent,
                                    },
                                    'less-loader'
                                ),
                            },
                            // "file" loader makes sure those assets get served by WebpackDevServer.
                            // When you `import` an asset, you get its (virtual) filename.
                            // In production, they would get copied to the `build` folder.
                            // 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
                                // its runtime that would otherwise be processed through "file" loader.
                                // Also exclude `html` and `json` extensions so they get processed
                                // by webpacks internal loaders.
                                exclude: [/.(js|mjs|jsx|ts|tsx)$/, /.html$/, /.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: [
                // Generates an `index.html` file with the <script> injected.
                new HtmlWebpackPlugin(
                    Object.assign(
                        {},
                        {
                            inject: true,
                            template: paths.appHtml,
                        },
                        isEnvProduction
                            ? {
                                minify: {
                                    removeComments: true,
                                    collapseWhitespace: true,
                                    removeRedundantAttributes: true,
                                    useShortDoctype: true,
                                    removeEmptyAttributes: true,
                                    removeStyleLinkTypeAttributes: true,
                                    keepClosingSlash: true,
                                    minifyJS: true,
                                    minifyCSS: true,
                                    minifyURLs: true,
                                },
                            }
                            : undefined
                    )
                ),
                // Inlines the webpack runtime script. This script is too small to warrant
                // a network request.
                isEnvProduction &&
                shouldInlineRuntimeChunk &&
                new InlineChunkHtmlPlugin(HtmlWebpackPlugin, [/runtime~.+[.]js/]),
                // 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.
                // In development, this will be an empty string.
                new InterpolateHtmlPlugin(HtmlWebpackPlugin, env.raw),
                // This gives some necessary context to module not found errors, such as
                // the requesting resource.
                new ModuleNotFoundPlugin(paths.appPath),
                // 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 is set to production
                // during a production build.
                // Otherwise React will be compiled in the very slow development mode.
                new webpack.DefinePlugin(env.stringified),
                // This is necessary to emit hot updates (currently CSS only):
                isEnvDevelopment && new webpack.HotModuleReplacementPlugin(),
                // Watcher doesn't work well if you mistype casing in a path so we use
                // a plugin that prints an error when you attempt to do this.
                // See https://github.com/facebook/create-react-app/issues/240
                isEnvDevelopment && new CaseSensitivePathsPlugin(),
                // If you require a missing module and then `npm install` it, you still have
                // to restart the development server for Webpack to discover it. This plugin
                // makes the discovery automatic so you don't have to restart.
                // See https://github.com/facebook/create-react-app/issues/186
                isEnvDevelopment &&
                new WatchMissingNodeModulesPlugin(paths.appNodeModules),
                isEnvProduction &&
                new MiniCssExtractPlugin({
                    // Options similar to the same options in webpackOptions.output
                    // both options are optional
                    filename: 'static/css/[name].[contenthash:8].css',
                    chunkFilename: 'static/css/[name].[contenthash:8].chunk.css',
                }),
                // 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',
                    publicPath: publicPath,
                    generate: (seed, files) => {
                        const manifestFiles = files.reduce(function (manifest, file) {
                            manifest[file.name] = file.path;
                            return manifest;
                        }, seed);
    
                        return {
                            files: manifestFiles,
                        };
                    },
                }),
                // 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$/, /moment$/),
                // Generate a service worker script that will precache, and keep up to date,
                // the HTML & assets that are part of the Webpack build.
                isEnvProduction &&
                new WorkboxWebpackPlugin.GenerateSW({
                    clientsClaim: true,
                    exclude: [/.map$/, /asset-manifest.json$/],
                    importWorkboxFrom: 'cdn',
                    navigateFallback: publicUrl + '/index.html',
                    navigateFallbackBlacklist: [
                        // Exclude URLs starting with /_, as they're likely an API call
                        new RegExp('^/_'),
                        // Exclude URLs containing a dot, as they're likely a resource in
                        // public/ and not a SPA route
                        new RegExp('/[^/]+\.[^/]+$'),
                    ],
                }),
                // TypeScript type checking
                useTypeScript &&
                new ForkTsCheckerWebpackPlugin({
                    typescript: resolve.sync('typescript', {
                        basedir: paths.appNodeModules,
                    }),
                    async: isEnvDevelopment,
                    useTypescriptIncrementalApi: true,
                    checkSyntacticErrors: true,
                    resolveModuleNameModule: process.versions.pnp
                        ? `${__dirname}/pnpTs.js`
                        : undefined,
                    resolveTypeReferenceDirectiveModule: process.versions.pnp
                        ? `${__dirname}/pnpTs.js`
                        : undefined,
                    tsconfig: paths.appTsConfig,
                    reportFiles: [
                        '**',
                        '!**/__tests__/**',
                        '!**/?(*.)(spec|test).*',
                        '!**/src/setupProxy.*',
                        '!**/src/setupTests.*',
                    ],
                    watch: paths.appSrc,
                    silent: true,
                    // The formatter is invoked directly in WebpackDevServerUtils during development
                    formatter: isEnvProduction ? typescriptFormatter : undefined,
                }),
            ].filter(Boolean),
            // 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: {
                module: 'empty',
                dgram: 'empty',
                dns: 'mock',
                fs: 'empty',
                http2: 'empty',
                net: 'empty',
                tls: 'empty',
                child_process: 'empty',
            },
            // Turn off performance processing because we utilize
            // our own hints via the FileSizeReporter
            performance: false,
        };
    };
    

      

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  • 原文地址:https://www.cnblogs.com/yang656/p/11315665.html
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