text: 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('react-dev-utils/InterpolateHtmlPlugin');
  const WatchMissingNodeModulesPlugin = require('react-dev-utils/WatchMissingNodeModulesPlugin');
  const eslintFormatter = require('react-dev-utils/eslintFormatter');
  const ModuleScopePlugin = require('react-dev-utils/ModuleScopePlugin');
  const ExtractTextPlugin = require('extract-text-webpack-plugin');
  
  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);
  
  const cssLoader = {
    loader: require.resolve('css-loader'),
    options: {
      importLoaders: 1,
    }
  };
  const babel = require('./babel');
  
  const postCssLoader = {
    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',
        }),
      ],
    },
  };
  
  // 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 = {
    // You may want 'eval' instead if you prefer to see the compiled output in DevTools.
    // See the discussion in https://github.com/facebookincubator/create-react-app/issues/343.
    devtool: '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.
    // The first two entry points enable "hot" CSS and auto-refreshes for JS.
    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'),
      require.resolve('react-dev-utils/webpackHotDevClient'),
      // We ship a few polyfills by default:
      require.resolve('./polyfills'),
      // Errors should be considered fatal in development
      require.resolve('react-error-overlay'),
      // Finally, this is your app's code:
      paths.indexJs,
      // 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: {
      // Next line is not used in dev but WebpackDevServer crashes without it:
      path: paths.build,
      // 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/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: 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/facebookincubator/create-react-app/issues/253
      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: ['.web.js', '.js', '.json', '.web.jsx', '.jsx'],
      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: [
        // 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.src),
      ],
    },
    module: {
      strictExportPresence: true,
      rules: [
        // ** ADDING/UPDATING LOADERS **
        // The "file" loader handles all assets unless explicitly excluded.
        // The `exclude` list *must* be updated with every change to loader extensions.
        // When adding a new loader, you must add its `test`
        // as a new entry in the `exclude` list for "file" 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.
        {
          exclude: [
            /\.html$/,
            /\.(js|jsx)$/,
            /\.css$/,
            /\.json$/,
            /\.bmp$/,
            /\.gif$/,
            /\.jpe?g$/,
            /\.png$/,
          ],
          loader: require.resolve('file-loader'),
          options: {
            name: 'static/media/[name].[hash:8].[ext]',
          },
        },
        // "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 JS with Babel.
        {
          test: /\.(js|jsx)$/,
          include: paths.src,
          loader: require.resolve('babel-loader'),
          options: babel
        },
  
        // "postcss" loader applies autoprefixer to our CSS.
        // "css" loader resolves paths in CSS and adds assets as dependencies.
        {
          test: /\.scss$/,
          loader: ExtractTextPlugin.extract(
            Object.assign(
              {
                fallback: require.resolve('style-loader'),
                use: [
                  cssLoader,
                  {
                    loader: require.resolve('sass-loader')
                  },
                  postCssLoader
                ]
              },
              {}
            )
          ),
        },
  
        // "postcss" loader applies autoprefixer to our CSS.
        // "css" loader resolves paths in CSS and adds assets as dependencies.
        {
          test: /\.css$/,
          use: [
            require.resolve('style-loader'),
            cssLoader,
            postCssLoader
          ],
        },
        // ** STOP ** Are you adding a new loader?
        // Remember to add the new extension(s) to the "file" loader exclusion list.
      ],
    },
    plugins: [
      // 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),
      // Generates an `index.html` file with the <script> injected.
      new HtmlWebpackPlugin({
        inject: true,
        template: paths.indexHtml,
      }),
      // 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/facebookincubator/create-react-app/issues/240
      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/facebookincubator/create-react-app/issues/186
      new WatchMissingNodeModulesPlugin(paths.appNodeModules),
      // 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 ExtractTextPlugin({
        filename: 'styles.css',
      }),
    ],
    // 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',
    },
    // 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,
    },
  };
  