webpack.config.js

const path = require('path');
const MiniCssExtractPlugin = require('mini-css-extract-plugin');
const WebpackShellPlugin = require('webpack-shell-plugin-next');
require('style-loader')
require('css-loader')
require('sass-loader')

module.exports = {
  mode: 'development',
  entry: ['./source/sass/2017/style.scss'],
  output: {
    path: path.resolve(__dirname, 'source/css'),
    filename: 'bundle.css'
  },
  plugins: [
    new MiniCssExtractPlugin(),
    new WebpackShellPlugin({ onBuildEnd: ['npx purgecss --output source/css/ --content ../../public/*.html ../../public/**/*.html source/js/*.js --css source/css/main.css'] })
  ],
  module: {
    rules: [
      {
        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',
        ],
      },
    ],
  },
};