webpack.config.js

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

const isDev = process.argv.includes('serve')

module.exports = {
  mode: isDev ? 'development' : 'production',
  entry: './src/index.js',
  output: {
    filename: 'main.js',
    path: path.resolve(__dirname, 'docs')
  },
  devServer: {
    contentBase: path.join(__dirname, 'docs'),
    open: true,
    port: 8989,
    watchContentBase: true
  },
  plugins: [
    new MiniCssExtractPlugin()
  ],
  module: {
    rules: [
      {
        test: /\.css$/i,
        use: [
          isDev ? 'style-loader' : MiniCssExtractPlugin.loader,
          'css-loader'
        ]
      },
      {
        test: /\.s[ac]ss$/i,
        use: [
          isDev ? 'style-loader' : MiniCssExtractPlugin.loader,
          'css-loader',
          {
            loader: 'postcss-loader',
            options: {
              postcssOptions: {
                plugins: [
                  ['autoprefixer', {}]
                ]
              }
            }
          },
          'sass-loader'
        ]
      }
    ]
  }
}