webpack.config.js

const path = require('path');
const autoprefixer = require('autoprefixer');

// Do this as the first thing so that any code reading it knows the right env.
process.env.BABEL_ENV = 'production';
process.env.NODE_ENV = 'production';
module.exports = {
  entry: './src/components/index.js',
  output: {
    path: path.resolve(__dirname, 'build'),
    filename: 'index.js',
    libraryTarget: 'commonjs2'
  },
  resolve: {
    extensions: ['.js', '.jsx'],
    modules: [path.resolve('./src'), path.resolve('./node_modules')],
    alias: {
      // my alias
      utils: path.resolve(__dirname, './src/utils/index.js'),
      const: path.resolve(__dirname, './src/const/index.js')
    }
  },
  module: {
    rules: [
      {
        test: /\.js|jsx$/,
        include: path.resolve(__dirname, 'src'),
        exclude: /(node_modules|bower_components|build)/,
        use: {
          loader: 'babel-loader'
        }
      },
      {
        test: /\.scss$/,
        include: path.resolve(__dirname, 'src'),
        use: [
          {
            loader: 'style-loader' // creates style nodes from JS strings
          },
          {
            loader: 'css-loader' // translates CSS into CommonJS
          },
          {
            loader: 'sass-loader' // compiles Sass to CSS
          }
        ]
      },
      {
        test: /\.css$/,
        use: [
          {
            loader: 'style-loader'
          },
          {
            loader: 'css-loader'
          },
          {
            loader: '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'
                })
              ]
            }
          }
        ]
      }
    ]
  },
  externals: {
    react: 'commonjs react',
    'react-dom': 'commonjs react-dom'
  }
};