class SomeClassName {
  foo = 'bar';
}

{
  "plugins": ["@babel/plugin-proposal-class-properties"]
}

const path = require('path');
const MiniCssExtractPlugin = require('mini-css-extract-plugin');

module.exports = {
  mode: 'development',
  entry: './src/scripts/main.js',
  devtool: "eval-source-map",
  output: {
    path: path.resolve(__dirname, 'src/dist'),
    filename: 'bundle.js',
  },
  module: {
    rules: [
      {
        test: /\.m?js$/,
        exclude: /(node_modules)/,
        use: {
          loader: 'babel-loader',
          options: {
            presets: ['@babel/preset-env'],
          }
        }
      },
      {
        test: /\.s[ac]ss$/i,
        use: [
          // Creates `style` nodes from JS strings
          MiniCssExtractPlugin.loader,
          // Translates CSS into CommonJS
          'css-loader',
          // Compiles Sass to CSS
          'sass-loader',
        ],
      },
    ]
  },
  plugins: [
    new MiniCssExtractPlugin({
      // Options similar to the same options in webpackOptions.output
      // both options are optional
      filename: '[name].css',
    }),
  ],
};

use: {
  loader: 'babel-loader',
  options: {
    presets: ['@babel/preset-env'],
    plugins: ['@babel/plugin-proposal-class-properties']
  }
}