This is my webpack config. There are many webpack configs, and this one is mine!

webpack.config.js

/* eslint-disable */
var path = require('path');
var MiniCssExtractPlugin = require('mini-css-extract-plugin');
var WriteFilePlugin = require('write-file-webpack-plugin');

var cssnano = require('cssnano');
var autoprefixer = require('autoprefixer');

var cssLoaderUse = function(asModules) {
  return [
    { loader: MiniCssExtractPlugin.loader },
    {
      loader: 'css-loader',
      options: { importLoaders: 1, modules: asModules, localIdentName: '[name]_[local]_[hash:base64:3]' }
    },
    {
      loader: 'postcss-loader',
      options: {
        plugins: [
          autoprefixer({
            browsers: [`last 2 versions`]
          }),
          cssnano()
        ]
      }
    },
    {
      loader: 'less-loader',
      options: {
        paths: [
          path.resolve(__dirname, 'src'),
          path.resolve(__dirname, 'src', 'common'),
          path.resolve(__dirname, 'node_modules')
        ]
      }
    }
  ];
};

module.exports = {
  entry: './src/index.js',
  devtool: 'source-map',
  resolve: {
    extensions: ['.js', '.jsx'],
    modules: ['node_modules', path.resolve(__dirname, 'src')],
    alias: {
      react: 'preact-compat',
      'mobx-react': 'mobx-preact',
      'react-dom': 'preact-compat'
    }
  },
  output: {
    path: path.resolve('./dist'),
    filename: 'editor.js'
  },
  plugins: [
    new MiniCssExtractPlugin({ filename: 'editor.css' }),
    new WriteFilePlugin()
  ],
  module: {
    rules: [
      {
        test: /\.jsx?$/,
        exclude: /(node_modules|bower_components)/,
        use: {
          loader: 'babel-loader',
          options: {
            presets: ['@babel/preset-env'],
            plugins: [
              ['@babel/plugin-proposal-decorators', { legacy: true }],
              '@babel/plugin-transform-runtime',
              '@babel/plugin-transform-react-jsx',
              '@babel/plugin-transform-flow-strip-types',
              ['@babel/plugin-transform-async-to-generator', {
                "module": "bluebird",
                "method": "coroutine"
              }],
              '@babel/plugin-proposal-object-rest-spread',
              ['@babel/plugin-proposal-class-properties', {loose: true}]
            ]
          }
        }
      },
      {
        test: /\.(le|c)ss$/,
        exclude: [/node_modules/, /common/],
        use: cssLoaderUse(true)
      },
      {
        test: /\.(le|c)ss$/,
        include: [/node_modules/, /common/],
        use: cssLoaderUse(false)
      }
    ]
  },
  mode: 'production',
  devServer: {
    stats: 'errors-only',
    port: process.env.port || 3000,
    publicPath: '/editor/',
    contentBase: path.join(__dirname, '..'),
    overlay: true,
    after: (a)=>{
      console.log('         http://localhost:' + (process.env.port || 3000) + '/editor/');
    }
  }
};