webpack.config.dev.js

## webpack.config.dev.js
const autoprefixer = require('autoprefixer');
const path = require('path');
const webpack = require('webpack');
const HtmlWebpackPlugin = require('html-webpack-plugin');
const CaseSensitivePathsPlugin = require('case-sensitive-paths-webpack-plugin');
const InterpolateHtmlPlugin = require('interpolate-html-plugin');
const eslintFormatter = require('react-dev-utils/eslintFormatter');
const ModuleScopePlugin = require('react-dev-utils/ModuleScopePlugin');
const getClientEnvironment = require('./env');
const paths = require('./paths');

// Webpack uses `publicPath` to determine where the app is being served from.
// In development, we always serve from the root. This makes config easier.
const 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_PATH%/xyz looks better than %PUBLIC_PATH%xyz.
const publicUrl = '';
// Get environment variables to inject into our app.
const env = getClientEnvironment(publicUrl);

// Options for PostCSS as we reference these options twice
// Adds vendor prefixing based on your specified browser support in
// package.json
const postCSSLoaderOptions = {
  // Necessary for external CSS imports to work
  // https://github.com/facebook/create-react-app/issues/2677
  ident: 'postcss',
  plugins: () => [
    require('postcss-flexbugs-fixes'),
    autoprefixer({
      flexbox: 'no-2009',
    }),
  ],
};

// This is the development configuration.
// It is focused on developer experience and fast rebuilds.
// The production configuration is different and lives in a separate file.
module.exports = {
  mode: 'development',
  // You may want 'eval' instead if you prefer to see the compiled output in DevTools.
  // See the discussion in https://github.com/facebook/create-react-app/issues/343.
  // TODO: vire - using `eval` instead of `cheap-module-source-map` make build/rebuild faster
  devtool: 'eval',
  // These are the "entry points" to our application.
  // This means they will be the "root" imports that are included in JS bundle.
  // The first two entry points enable "hot" CSS and auto-refreshes for JS.
  entry: [
    // We ship a few polyfills by default:
    require.resolve('./polyfills'),
    // 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'),
    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.
  ],
  output: {
    // Add /* filename */ comments to generated require()s in the output.
    pathinfo: true,
    // This does not produce a real file. It's just the virtual path that is
    // served by WebpackDevServer in development. This is the JS bundle
    // containing code from all our entry points, and the Webpack runtime.
    filename: 'static/js/[name].bundle.js',
    // There are also additional JS chunk files if you use code splitting.
    chunkFilename: 'static/js/[name].chunk.js',
    // This is the URL that app is served from. We use "/" in development.
    publicPath,
    // Point sourcemap entries to original disk location (format as URL on Windows)
    devtoolModuleFilenameTemplate: info =>
      path.resolve(info.absoluteResourcePath).replace(/\\/g, '/'),
  },
  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'].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/facebook/create-react-app/issues/290
    // `web` extension prefixes have been added for better support
    // for React Native Web.
    extensions: ['.web.js', '.mjs', '.js', '.json', '.web.jsx', '.jsx'],
    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: {
    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|jsx|mjs)$/,
        enforce: 'pre',
        use: [
          {
            options: {
              formatter: eslintFormatter,
              eslintPath: require.resolve('eslint'),
            },
            loader: require.resolve('eslint-loader'),
          },
        ],
        include: paths.srcPaths,
        exclude: [/[/\\\\]node_modules[/\\\\]/],
      },
      {
        // "oneOf" will traverse all following loaders until one will
        // match the requirements. When no loader matches it will fall
        // back to the "file" loader at the end of the loader list.
        oneOf: [
          // "url" loader works like "file" loader except that it embeds assets
          // smaller than specified limit in bytes as data URLs to avoid requests.
          // A missing `test` is equivalent to a match.
          {
            test: [/\.bmp$/, /\.gif$/, /\.jpe?g$/, /\.png$/],
            loader: require.resolve('url-loader'),
            options: {
              limit: 10000,
              name: 'static/media/[name].[hash:8].[ext]',
            },
          },
          // Process application JS with Babel.
          // The preset includes JSX, Flow, and some ESnext features.
          {
            test: /\.(js|jsx|mjs)$/,
            include: paths.srcPaths,
            exclude: [/[/\\\\]node_modules[/\\\\]/],
            use: [
              // This loader parallelizes code compilation, it is optional but
              // improves compile time on larger projects
              require.resolve('thread-loader'),
              {
                loader: require.resolve('babel-loader'),
                options: {
                  presets: [require.resolve('babel-preset-react-app')],
                  plugins: [
                    [
                      require.resolve('babel-plugin-named-asset-import'),
                      {
                        loaderMap: {
                          svg: {
                            ReactComponent: 'svgr/webpack![path]',
                          },
                        },
                      },
                    ],
                  ],
                  // 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,
                  highlightCode: true,
                },
              },
            ],
          },
          // Process any JS outside of the app with Babel.
          // Unlike the application JS, we only compile the standard ES features.
          {
            test: /\.js$/,
            use: [
              // This loader parallelizes code compilation, it is optional but
              // improves compile time on larger projects
              require.resolve('thread-loader'),
              {
                loader: require.resolve('babel-loader'),
                options: {
                  babelrc: false,
                  compact: false,
                  presets: [
                    require.resolve('babel-preset-react-app/dependencies'),
                  ],
                  cacheDirectory: true,
                  highlightCode: true,
                },
              },
            ],
          },
          // "postcss" loader applies autoprefixer to our CSS.
          // "css" loader resolves paths in CSS and adds assets as dependencies.
          // "style" loader turns CSS into JS modules that inject <style> tags.
          // In production, we use a plugin to extract that CSS to a file, but
          // in development "style" loader enables hot editing of CSS.
          // By default we support CSS Modules with the extension .module.css
          {
            test: /\.css$/,
            exclude: /\.module\.css$/,
            use: [
              require.resolve('style-loader'),
              {
                loader: require.resolve('css-loader'),
                options: {
                  importLoaders: 1,
                },
              },
              {
                loader: require.resolve('postcss-loader'),
                options: postCSSLoaderOptions,
              },
            ],
          },
          // Adds support for CSS Modules (https://github.com/css-modules/css-modules)
          // using the extension .module.css
          {
            test: /\.module\.css$/,
            use: [
              require.resolve('style-loader'),
              {
                loader: require.resolve('css-loader'),
                options: {
                  importLoaders: 1,
                  modules: true,
                  localIdentName: '[path]__[name]___[local]',
                },
              },
              {
                loader: require.resolve('postcss-loader'),
                options: postCSSLoaderOptions,
              },
            ],
          },
          // The GraphQL loader preprocesses GraphQL queries in .graphql files.
          {
            test: /\.(graphql)$/,
            loader: 'graphql-tag/loader',
          },
          // "file" loader makes sure those assets get served by WebpackDevServer.
          // When you `import` an asset, you get its (virtual) filename.
          // In production, they would get copied to the `build` folder.
          // This loader doesn't use a "test" so it will catch all modules
          // that fall through the other loaders.
          {
            // Exclude `js` files to keep "css" loader working as it injects
            // its runtime that would otherwise be processed through "file" loader.
            // Also exclude `html` and `json` extensions so they get processed
            // by webpacks internal loaders.
            exclude: [/\.(js|jsx|mjs)$/, /\.html$/, /\.json$/],
            loader: require.resolve('file-loader'),
            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.
    ],
  },
  optimization: {
    splitChunks: {
      cacheGroups: {
        commons: {
          test: /[\\/]node_modules[\\/]/,
          name: 'vendor',
          chunks: 'initial',
        },
      },
    },
  },
  plugins: [
    new webpack.LoaderOptionsPlugin({
      options: {
        context: process.cwd(), // or the same value as `context`
      },
    }),
    // Generates an `index.html` file with the <script> injected.
    new HtmlWebpackPlugin({
      inject: true,
      template: paths.appHtml,
      chunksSortMode: 'none',
    }),
    // 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 development, this will be an empty string.
    new InterpolateHtmlPlugin(env.raw),
    // Add module names to factory functions so they appear in browser profiler.
    new webpack.NamedModulesPlugin(),
    // Makes some environment variables available to the JS code, for example:
    // if (process.env.NODE_ENV === 'development') { ... }. See `./env.js`.
    new webpack.DefinePlugin(env.stringified),
    // This is necessary to emit hot updates (currently CSS only):
    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
    new CaseSensitivePathsPlugin(),
    // 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',
  },
  // Turn off performance hints during development because we don't do any
  // splitting or minification in interest of speed. These warnings become
  // cumbersome.
  performance: {
    hints: false,
  },
};

## webpack.config.prod.js
const autoprefixer = require('autoprefixer');
const path = require('path');
const webpack = require('webpack');
const HtmlWebpackPlugin = require('html-webpack-plugin');
const UglifyJsPlugin = require('uglifyjs-webpack-plugin');
const ExtractTextPlugin = require('extract-text-webpack-plugin');
const ManifestPlugin = require('webpack-manifest-plugin');
const InterpolateHtmlPlugin = require('interpolate-html-plugin');
const eslintFormatter = require('react-dev-utils/eslintFormatter');
const ModuleScopePlugin = require('react-dev-utils/ModuleScopePlugin');
const SpeedMeasurePlugin = require('speed-measure-webpack-plugin');

const paths = require('./paths');
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;
// 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].[md5:contenthash:hex:20].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('../') }
  : {};

// Options for PostCSS as we reference these options twice
// Adds vendor prefixing based on your specified browser support in
// package.json
const postCSSLoaderOptions = {
  // Necessary for external CSS imports to work
  // https://github.com/facebook/create-react-app/issues/2677
  ident: 'postcss',
  plugins: () => [
    require('postcss-flexbugs-fixes'),
    autoprefixer({
      flexbox: 'no-2009',
    }),
  ],
};

// 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 = {
  mode: 'production',
  // 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],
  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,
    // Point sourcemap entries to original disk location (format as URL on Windows)
    devtoolModuleFilenameTemplate: info =>
      path
        .relative(paths.appSrc, info.absoluteResourcePath)
        .replace(/\\/g, '/'),
  },
  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'].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/facebook/create-react-app/issues/290
    // `web` extension prefixes have been added for better support
    // for React Native Web.
    extensions: ['.web.js', '.mjs', '.js', '.json', '.web.jsx', '.jsx'],
    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: {
    strictExportPresence: true,
    rules: [
      // Disable require.ensure as it's not a standard language feature.
      { parser: { requireEnsure: false } },
      {
        test: /\.(js|jsx|mjs)$/,
        enforce: 'pre',
        use: [
          {
            options: {
              formatter: eslintFormatter,
              eslintPath: require.resolve('eslint'),
              // TODO: consider separate config for production,
              // e.g. to enable no-console and no-debugger only in production.
            },
            loader: require.resolve('eslint-loader'),
          },
        ],
        include: paths.srcPaths,
        exclude: [/[/\\\\]node_modules[/\\\\]/],
      },
      {
        // "oneOf" will traverse all following loaders until one will
        // match the requirements. When no loader matches it will fall
        // back to the "file" loader at the end of the loader list.
        oneOf: [
          // "url" loader works just like "file" loader but it also embeds
          // assets smaller than specified size as data URLs to avoid requests.
          {
            test: [/\.bmp$/, /\.gif$/, /\.jpe?g$/, /\.png$/],
            loader: require.resolve('url-loader'),
            options: {
              limit: 10000,
              name: 'static/media/[name].[hash:8].[ext]',
            },
          },
          // Process application JS with Babel.
          // The preset includes JSX, Flow, and some ESnext features.
          {
            test: /\.(js|jsx|mjs)$/,
            include: paths.srcPaths,
            exclude: [/[/\\\\]node_modules[/\\\\]/],
            use: [
              // This loader parallelizes code compilation, it is optional but
              // improves compile time on larger projects
              require.resolve('thread-loader'),
              {
                loader: require.resolve('babel-loader'),
                options: {
                  presets: [require.resolve('babel-preset-react-app')],
                  plugins: [
                    [
                      require.resolve('babel-plugin-named-asset-import'),
                      {
                        loaderMap: {
                          svg: {
                            ReactComponent: 'svgr/webpack![path]',
                          },
                        },
                      },
                    ],
                  ],
                  compact: true,
                  highlightCode: true,
                },
              },
            ],
          },
          // Process any JS outside of the app with Babel.
          // Unlike the application JS, we only compile the standard ES features.
          {
            test: /\.js$/,
            use: [
              // This loader parallelizes code compilation, it is optional but
              // improves compile time on larger projects
              require.resolve('thread-loader'),
              {
                loader: require.resolve('babel-loader'),
                options: {
                  babelrc: false,
                  compact: false,
                  presets: [
                    require.resolve('babel-preset-react-app/dependencies'),
                  ],
                  cacheDirectory: true,
                  highlightCode: true,
                },
              },
            ],
          },
          // The notation here is somewhat confusing.
          // "postcss" loader applies autoprefixer to our CSS.
          // "css" loader resolves paths in CSS and adds assets as dependencies.
          // "style" loader normally turns CSS into JS modules injecting <style>,
          // but unlike in development configuration, we do something different.
          // `ExtractTextPlugin` first applies the "postcss" and "css" loaders
          // (second argument), then grabs the result CSS and puts it into a
          // separate file in our build process. This way we actually ship
          // a single CSS file in production instead of JS code injecting <style>
          // tags. If you use code splitting, however, any async bundles will still
          // use the "style" loader inside the async code so CSS from them won't be
          // in the main CSS file.
          // By default we support CSS Modules with the extension .module.css
          {
            test: /\.css$/,
            exclude: /\.module\.css$/,
            loader: ExtractTextPlugin.extract(
              Object.assign(
                {
                  fallback: {
                    loader: require.resolve('style-loader'),
                    options: {
                      hmr: false,
                    },
                  },
                  use: [
                    {
                      loader: require.resolve('css-loader'),
                      options: {
                        importLoaders: 1,
                        minimize: true,
                        sourceMap: shouldUseSourceMap,
                      },
                    },
                    {
                      loader: require.resolve('postcss-loader'),
                      options: postCSSLoaderOptions,
                    },
                  ],
                },
                extractTextPluginOptions
              )
            ),
            // Note: this won't work without `new ExtractTextPlugin()` in `plugins`.
          },
          // Adds support for CSS Modules (https://github.com/css-modules/css-modules)
          // using the extension .module.css
          {
            test: /\.module\.css$/,
            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,
                        modules: true,
                        localIdentName: '[path]__[name]___[local]',
                      },
                    },
                    {
                      loader: require.resolve('postcss-loader'),
                      options: postCSSLoaderOptions,
                    },
                  ],
                },
                extractTextPluginOptions
              )
            ),
            // Note: this won't work without `new ExtractTextPlugin()` in `plugins`.
          },
          // The GraphQL loader preprocesses GraphQL queries in .graphql files.
          {
            test: /\.(graphql)$/,
            loader: 'graphql-tag/loader',
          },
          // "file" loader makes sure assets end up in the `build` folder.
          // When you `import` an asset, you get its filename.
          // This loader doesn't use a "test" so it will catch all modules
          // that fall through the other loaders.
          {
            loader: require.resolve('file-loader'),
            // Exclude `js` files to keep "css" loader working as it injects
            // it's runtime that would otherwise be processed through "file" loader.
            // Also exclude `html` and `json` extensions so they get processed
            // by webpacks internal loaders.
            exclude: [/\.(js|jsx|mjs)$/, /\.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.
        ],
      },
    ],
  },
  optimization: {
    splitChunks: {
      cacheGroups: {
        commons: {
          test: /[\\/]node_modules[\\/]/,
          name: 'vendor',
          chunks: 'initial',
        },
      },
    },
    minimizer: [
      // Minify the code.
      new UglifyJsPlugin({
        uglifyOptions: {
          compress: {
            // 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,
          },
          output: {
            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
        parallel: true,
        // Enable file caching
        cache: true,
        sourceMap: shouldUseSourceMap,
      }),
    ],
  },
  plugins: [
    // TODO: vire - LoaderOptionsPlugin needs to be removed
    // see https://github.com/webpack/webpack/issues/6064
    new webpack.LoaderOptionsPlugin({
      options: {
        context: process.cwd(), // or the same value as `context`
      },
    }),
    // 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,
      },
    }),
    // 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),
    // 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),

    // 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',
      publicPath,
    }),
    // 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$/, /moment$/),
    new SpeedMeasurePlugin(),
  ],
  // 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',
  },
};
	const autoprefixer = require('autoprefixer');
	const path = require('path');
	const webpack = require('webpack');
	const HtmlWebpackPlugin = require('html-webpack-plugin');
	const CaseSensitivePathsPlugin = require('case-sensitive-paths-webpack-plugin');
	const InterpolateHtmlPlugin = require('interpolate-html-plugin');
	const eslintFormatter = require('react-dev-utils/eslintFormatter');
	const ModuleScopePlugin = require('react-dev-utils/ModuleScopePlugin');
	const getClientEnvironment = require('./env');
	const paths = require('./paths');

	// Webpack uses `publicPath` to determine where the app is being served from.
	// In development, we always serve from the root. This makes config easier.
	const 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_PATH%/xyz looks better than %PUBLIC_PATH%xyz.
	const publicUrl = '';
	// Get environment variables to inject into our app.
	const env = getClientEnvironment(publicUrl);

	// Options for PostCSS as we reference these options twice
	// Adds vendor prefixing based on your specified browser support in
	// package.json
	const postCSSLoaderOptions = {
	// Necessary for external CSS imports to work
	// https://github.com/facebook/create-react-app/issues/2677
	ident: 'postcss',
	plugins: () => [
	require('postcss-flexbugs-fixes'),
	autoprefixer({
	flexbox: 'no-2009',
	}),
	],
	};

	// This is the development configuration.
	// It is focused on developer experience and fast rebuilds.
	// The production configuration is different and lives in a separate file.
	module.exports = {
	mode: 'development',
	// You may want 'eval' instead if you prefer to see the compiled output in DevTools.
	// See the discussion in https://github.com/facebook/create-react-app/issues/343.
	// TODO: vire - using `eval` instead of `cheap-module-source-map` make build/rebuild faster
	devtool: 'eval',
	// These are the "entry points" to our application.
	// This means they will be the "root" imports that are included in JS bundle.
	// The first two entry points enable "hot" CSS and auto-refreshes for JS.
	entry: [
	// We ship a few polyfills by default:
	require.resolve('./polyfills'),
	// 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'),
	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.
	],
	output: {
	// Add /* filename */ comments to generated require()s in the output.
	pathinfo: true,
	// This does not produce a real file. It's just the virtual path that is
	// served by WebpackDevServer in development. This is the JS bundle
	// containing code from all our entry points, and the Webpack runtime.
	filename: 'static/js/[name].bundle.js',
	// There are also additional JS chunk files if you use code splitting.
	chunkFilename: 'static/js/[name].chunk.js',
	// This is the URL that app is served from. We use "/" in development.
	publicPath,
	// Point sourcemap entries to original disk location (format as URL on Windows)
	devtoolModuleFilenameTemplate: info =>
	path.resolve(info.absoluteResourcePath).replace(/\\/g, '/'),
	},
	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'].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/facebook/create-react-app/issues/290
	// `web` extension prefixes have been added for better support
	// for React Native Web.
	extensions: ['.web.js', '.mjs', '.js', '.json', '.web.jsx', '.jsx'],
	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: {
	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\|jsx\|mjs)$/,
	enforce: 'pre',
	use: [
	{
	options: {
	formatter: eslintFormatter,
	eslintPath: require.resolve('eslint'),
	},
	loader: require.resolve('eslint-loader'),
	},
	],
	include: paths.srcPaths,
	exclude: [/[/\\\\]node_modules[/\\\\]/],
	},
	{
	// "oneOf" will traverse all following loaders until one will
	// match the requirements. When no loader matches it will fall
	// back to the "file" loader at the end of the loader list.
	oneOf: [
	// "url" loader works like "file" loader except that it embeds assets
	// smaller than specified limit in bytes as data URLs to avoid requests.
	// A missing `test` is equivalent to a match.
	{
	test: [/\.bmp$/, /\.gif$/, /\.jpe?g$/, /\.png$/],
	loader: require.resolve('url-loader'),
	options: {
	limit: 10000,
	name: 'static/media/[name].[hash:8].[ext]',
	},
	},
	// Process application JS with Babel.
	// The preset includes JSX, Flow, and some ESnext features.
	{
	test: /\.(js\|jsx\|mjs)$/,
	include: paths.srcPaths,
	exclude: [/[/\\\\]node_modules[/\\\\]/],
	use: [
	// This loader parallelizes code compilation, it is optional but
	// improves compile time on larger projects
	require.resolve('thread-loader'),
	{
	loader: require.resolve('babel-loader'),
	options: {
	presets: [require.resolve('babel-preset-react-app')],
	plugins: [
	[
	require.resolve('babel-plugin-named-asset-import'),
	{
	loaderMap: {
	svg: {
	ReactComponent: 'svgr/webpack![path]',
	},
	},
	},
	],
	],
	// 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,
	highlightCode: true,
	},
	},
	],
	},
	// Process any JS outside of the app with Babel.
	// Unlike the application JS, we only compile the standard ES features.
	{
	test: /\.js$/,
	use: [
	// This loader parallelizes code compilation, it is optional but
	// improves compile time on larger projects
	require.resolve('thread-loader'),
	{
	loader: require.resolve('babel-loader'),
	options: {
	babelrc: false,
	compact: false,
	presets: [
	require.resolve('babel-preset-react-app/dependencies'),
	],
	cacheDirectory: true,
	highlightCode: true,
	},
	},
	],
	},
	// "postcss" loader applies autoprefixer to our CSS.
	// "css" loader resolves paths in CSS and adds assets as dependencies.
	// "style" loader turns CSS into JS modules that inject <style> tags.
	// In production, we use a plugin to extract that CSS to a file, but
	// in development "style" loader enables hot editing of CSS.
	// By default we support CSS Modules with the extension .module.css
	{
	test: /\.css$/,
	exclude: /\.module\.css$/,
	use: [
	require.resolve('style-loader'),
	{
	loader: require.resolve('css-loader'),
	options: {
	importLoaders: 1,
	},
	},
	{
	loader: require.resolve('postcss-loader'),
	options: postCSSLoaderOptions,
	},
	],
	},
	// Adds support for CSS Modules (https://github.com/css-modules/css-modules)
	// using the extension .module.css
	{
	test: /\.module\.css$/,
	use: [
	require.resolve('style-loader'),
	{
	loader: require.resolve('css-loader'),
	options: {
	importLoaders: 1,
	modules: true,
	localIdentName: '[path]__[name]___[local]',
	},
	},
	{
	loader: require.resolve('postcss-loader'),
	options: postCSSLoaderOptions,
	},
	],
	},
	// The GraphQL loader preprocesses GraphQL queries in .graphql files.
	{
	test: /\.(graphql)$/,
	loader: 'graphql-tag/loader',
	},
	// "file" loader makes sure those assets get served by WebpackDevServer.
	// When you `import` an asset, you get its (virtual) filename.
	// In production, they would get copied to the `build` folder.
	// This loader doesn't use a "test" so it will catch all modules
	// that fall through the other loaders.
	{
	// Exclude `js` files to keep "css" loader working as it injects
	// its runtime that would otherwise be processed through "file" loader.
	// Also exclude `html` and `json` extensions so they get processed
	// by webpacks internal loaders.
	exclude: [/\.(js\|jsx\|mjs)$/, /\.html$/, /\.json$/],
	loader: require.resolve('file-loader'),
	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.
	],
	},
	optimization: {
	splitChunks: {
	cacheGroups: {
	commons: {
	test: /[\\/]node_modules[\\/]/,
	name: 'vendor',
	chunks: 'initial',
	},
	},
	},
	},
	plugins: [
	new webpack.LoaderOptionsPlugin({
	options: {
	context: process.cwd(), // or the same value as `context`
	},
	}),
	// Generates an `index.html` file with the <script> injected.
	new HtmlWebpackPlugin({
	inject: true,
	template: paths.appHtml,
	chunksSortMode: 'none',
	}),
	// 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 development, this will be an empty string.
	new InterpolateHtmlPlugin(env.raw),
	// Add module names to factory functions so they appear in browser profiler.
	new webpack.NamedModulesPlugin(),
	// Makes some environment variables available to the JS code, for example:
	// if (process.env.NODE_ENV === 'development') { ... }. See `./env.js`.
	new webpack.DefinePlugin(env.stringified),
	// This is necessary to emit hot updates (currently CSS only):
	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
	new CaseSensitivePathsPlugin(),
	// 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',
	},
	// Turn off performance hints during development because we don't do any
	// splitting or minification in interest of speed. These warnings become
	// cumbersome.
	performance: {
	hints: false,
	},
	};