webpack.config.js

const HtmlWebpackPlugin = require('html-webpack-plugin');
const MiniCssExtractPlugin = require('mini-css-extract-plugin');
const webpack = require('webpack');
const dotenv = require('dotenv');
const path = require('path');

module.exports = {
  entry: './src/index.js',
  target: 'web',
  mode: 'development',
  devtool: 'inline-source-map',
  module: {
    rules: [
      {
        test: /\.html$/,
        use: [
          {
            loader: 'html-loader',
            options: { minimize: true }
          }
        ]
      },
      {
        test: /\.js$/,
        exclude: /node_modules/,
        use: {
          loader: 'babel-loader',
          options: {
            presets: ['@babel/preset-env']
          }
        }
      },
      {
        test: /\.(css)$/,
        use: ['style-loader', 'css-loader', 'postcss-loader']
      }
    ]
  },
  plugins: [
    new webpack.DefinePlugin({
      'process.env': JSON.stringify(dotenv.config().parsed) // it will automatically pick up key values from .env file
    }),
    new HtmlWebpackPlugin({
      template: 'src/index.html'
    }),
    new MiniCssExtractPlugin({
      filename: '[name].css',
      chunkFilename: '[id].css'
    }),
    new webpack.HotModuleReplacementPlugin()
  ],
  devServer: {
    contentBase: path.resolve(__dirname, 'dist'),
    hot: false,
    host: 'localhost',
    port: 9000,
    writeToDisk: true
  },
  output: {
    publicPath: './'
  }
};