webpack.config.js

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

module.exports = {
  entry: './src/index.js',
  output: {
    path: path.resolve(__dirname, 'dist'),
    filename: 'bundle.js',
  },
  devServer: {
    static: path.join(__dirname, 'public'),
    historyApiFallback: true,
  },
  module: {
    rules: [
      {
        test: /\.(js|jsx)$/,
        exclude: /node_modules/,
        use: {
          loader: 'babel-loader',
        },
      },
    ],
  },
  plugins: [
    new HtmlWebpackPlugin({
      template: './public/index.html',
    }),
		new Dotenv({
      safe: true, // load '.env.example' to verify the '.env' variables are all set. Can also be a string to a different file.
      allowEmptyValues: true, // allow empty variables (e.g. `FOO=`) (treat it as empty string, rather than missing)
      systemvars: true, // load all the predefined 'process.env' variables which will trump anything local per dotenv specs.
      silent: true, // hide any errors
      defaults: false, // load '.env.defaults' as the default values if empty.
    })
  ],
};