text: var autoprefixer = require('autoprefixer');
  var webpack = require('webpack');
  var HtmlWebpackPlugin = require('html-webpack-plugin');
  var CaseSensitivePathsPlugin = require('case-sensitive-paths-webpack-plugin');
  var InterpolateHtmlPlugin = require('react-dev-utils/InterpolateHtmlPlugin');
  var WatchMissingNodeModulesPlugin = require('react-dev-utils/WatchMissingNodeModulesPlugin');
  var getClientEnvironment = require('./env');
  var 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.
  var 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.
  var publicUrl = '';
  // Get environment variables to inject into our app.
  var env = getClientEnvironment(publicUrl);
  
  // 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'),
      // 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: {
      // Next line is not used in dev but WebpackDevServer crashes without it:
      path: paths.appBuild,
      // 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',
      // This is the URL that app is served from. We use "/" in development.
      publicPath: publicPath
    },
    resolve: {
      // This allows you to set a fallback for where Webpack should look for modules.
      // We read `NODE_PATH` environment variable in `paths.js` and pass paths here.
      // We use `fallback` instead of `root` because we want `node_modules` to "win"
      // if there any conflicts. This matches Node resolution mechanism.
      // https://github.com/facebookincubator/create-react-app/issues/253
      fallback: paths.nodePaths,
      // 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
      extensions: ['.js', '.json', '.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'
      }
    },
    
    module: {
      // First, run the linter.
      // It's important to do this before Babel processes the JS.
      preLoaders: [
        {
          test: /\.(js|jsx)$/,
          loader: 'eslint',
          include: paths.appSrc,
        }
      ],
      loaders: [
        // Default loader: load all assets that are not handled
        // by other loaders with the url loader.
        // Note: This list needs to be updated with every change of extensions
        // the other loaders match.
        // E.g., when adding a loader for a new supported file extension,
        // we need to add the supported extension to this loader too.
        // Add one new line in `exclude` for each loader.
        //
        // "file" loader makes sure those assets get served by WebpackDevServer.
        // When you `import` an asset, you get its (virtual) filename.
        // In production, they would get copied to the `build` folder.
        // "url" loader works like "file" loader except that it embeds assets
        // smaller than specified limit in bytes as data URLs to avoid requests.
        // A missing `test` is equivalent to a match.
        {
          exclude: [
            /\.html$/,
            /\.(js|jsx)$/,
            /\.css$/,
            /\.json$/,
            /\.svg$/,
            /\.scss$/
          ],
          loader: 'url',
          query: {
            limit: 10000,
            name: 'static/media/[name].[hash:8].[ext]'
          }
        },
        // Process JS with Babel.
        {
          test: /\.(js|jsx)$/,
          include: paths.appSrc,
          loader: 'babel',
          query: {
            
            // 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
          }
        },
        // Process SCSS
        {
          test: /\.scss$/,
          include: paths.appSrc,
          loaders: ["style", "css", "sass"]
        },
        // "postcss" loader applies autoprefixer to our CSS.
        // "css" loader resolves paths in CSS and adds assets as dependencies.
        // "style" loader turns CSS into JS modules that inject <style> tags.
        // In production, we use a plugin to extract that CSS to a file, but
        // in development "style" loader enables hot editing of CSS.
        {
          test: /\.css$/,
          loader: 'style!css?importLoaders=1!postcss'
        },
        // JSON is not enabled by default in Webpack but both Node and Browserify
        // allow it implicitly so we also enable it.
        {
          test: /\.json$/,
          loader: 'json'
        },
        // "file" loader for svg
        {
          test: /\.svg$/,
          loader: 'file',
          query: {
            name: 'static/media/[name].[hash:8].[ext]'
          }
        }
      ]
    },
    
    // We use PostCSS for autoprefixing only.
    postcss: function() {
      return [
        autoprefixer({
          browsers: [
            '>1%',
            'last 4 versions',
            'Firefox ESR',
            'not ie < 9', // React doesn't support IE8 anyway
          ]
        }),
      ];
    },
    plugins: [
      // Makes the public URL 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({
        PUBLIC_URL: publicUrl
      }),
      // Generates an `index.html` file with the <script> injected.
      new HtmlWebpackPlugin({
        inject: true,
        template: paths.appHtml,
      }),
      // Makes some environment variables available to the JS code, for example:
      // if (process.env.NODE_ENV === 'development') { ... }. See `./env.js`.
      new webpack.DefinePlugin(env),
      // 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)
    ],
    // 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: {
      fs: 'empty',
      net: 'empty',
      tls: 'empty'
    }
  };
  