webpack.config.js

const path = require('path')
const CopyWebpackPlugin = require('copy-webpack-plugin')

module.exports = {
  entry: './app/scripts/index.js',
  mode: 'production',
  output: {
    path: path.resolve(__dirname, 'build'),
    filename: 'app.js'
  },
  plugins: [
    // Copy our app's index.html to the build folder.
    new CopyWebpackPlugin([{ from: './app/index.html', to: 'index.html' }])
  ],
  devtool: 'source-map',
  module: {
    rules: [
      {
        test: /\.(png|jpg|gif|svg)$/,
        loader: 'file-loader',
        options: {
          name: '[name].[ext]?[hash]'
        }
      },
      {
        test: /\.(css|less|scss)$/,
        use: ['style-loader', 'css-loader', 'sass-loader', 'less-loader']
      },
      {
        test: require.resolve('jquery'),
        use: [{
          loader: 'expose-loader',
          options: 'jQuery'
        }, {
          loader: 'expose-loader',
          options: '$'
        }]
      },
      {
        test: /\.js$/,
        exclude: /(node_modules|bower_components)/,
        loader: 'babel-loader',
        query: {
          presets: ['env'],
          plugins: [
            'transform-react-jsx',
            'transform-object-rest-spread',
            'transform-runtime'
          ]
        }
      }
    ]
  }
};