webpack.config.js

const MiniCssExtractPlugin = require('mini-css-extract-plugin')
const OptimizeCSSAssetsPlugin = require('optimize-css-assets-webpack-plugin')

module.exports = {
  mode: 'development',
  entry : {
    'assets/main': './assets/main.js',
  },
  module: {
    rules: [
      {
        test: /\.js$/,
        exclude: /(node_modules)/,
        use: [
          {
            loader: 'babel-loader',
            options: {
              presets: ['@babel/preset-env'],
              plugins: ['@babel/plugin-transform-runtime']
            }
          },
          {
            loader: 'eslint-loader'
          }
        ]
      },
      {
        test: /\.css$/,
        use: [
          MiniCssExtractPlugin.loader,
          'css-loader'
        ]
      },
      {
        test: /\.scss$/i,
        exclude: /node_modules/,
        use: [
          {
            loader: MiniCssExtractPlugin.loader,
          },
          {
            loader: 'css-loader',
            options: {
              url: false,
              import: false
            }
          },
          {
            loader: 'postcss-loader',
            options: {
              plugins: [
                require('autoprefixer')()
              ]
            }
          },
          {
            loader: 'sass-loader',
          },
        ],
      },
    ],
  },
  plugins: [
    new MiniCssExtractPlugin(),
    new OptimizeCSSAssetsPlugin()
  ],
};