webpack.config.js

const Dotenv = require('dotenv-webpack');

module.exports = {
  entry: './src/index.js',
  output: {
    path: `${__dirname}/build`,
    filename: 'bundle.js'
  },
  module: {
    rules: [
      {
        test: /\.js$/,
        use: [
          {
            loader: 'babel-loader',
            options: {
              presets: [
                ['env', {
                  'exclude': ['transform-regenerator']
                }],
                'react'
              ]
            }
          }
        ],
        exclude: /node_modules/,
      },
      {
        test: /\.css$/,
        use: [
          'style-loader',
          {
            loader: 'css-loader',
            options: {
              importLoaders: 1
            }
          },
          {
            loader: 'postcss-loader',
            options: {
              ident: 'postcss',
              plugins: () => { }
            }
          }
        ]
      }
    ]
  },
  plugins: [
    new Dotenv({
      path: './.env'
    })
  ],
  devServer: {
    contentBase: './public',
    port: 8080,
    inline: true,
    historyApiFallback: true
  },
  devtool: 'source-map'
};