webpack.config.js

const path = require('path');
const Dotenv = require('dotenv-webpack');
const HtmlWebpackPlugin = require('html-webpack-plugin');

module.exports = {
  entry: path.join(__dirname, 'src', 'index.js'),
  output: {
    path: path.join(__dirname, 'build'),
    filename: 'bundle.js'
  },
  mode: process.env.NODE_ENV || 'development',
  resolve: {
    extensions: ['.js', '.jsx', '.json']
  },
  module: {
    rules: [
      {
        test: /\.jsx?$/,
        exclude: /node_modules/,
        loader: 'babel-loader'
      },
      {
        test: /\.css$/,
        loader: ['style-loader', 'css-loader']
      }
    ]
  },
  plugins: [
    new HtmlWebpackPlugin({
      template: path.join(__dirname, 'public', 'index.html')
    }),
    new Dotenv({
      systemvars: true
    })
  ],
  target: 'node'
};