webpack.config.dev.js

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

module.exports = {
  mode: 'development',
  entry: [
    'webpack-dev-server/client?http://0.0.0.0:3000',
    'webpack/hot/only-dev-server',
    path.join(__dirname, 'example/src/index.jsx')
  ],
  output: {
    path: path.join(__dirname, 'example/assets'),
    filename: 'bundle.js',
    publicPath: '/assets/'
  },
  module: {
    rules: [
      {
        test: /\.jsx?$/,
        loaders: [
          'react-hot-loader/webpack',
          'babel-loader',
        ],
        include: path.join(__dirname),
        exclude: [
          /node_modules/
        ]
      },
      {
        test: /\.css$/,
        include: path.join(__dirname),
        use: [
          {
            loader: MiniCssExtractPlugin.loader,
          },
          'css-loader'
        ]
      },
    ],
  },
   resolve: {
    extensions: ['.js', '.jsx'],
  },
  plugins: [
    new webpack.HotModuleReplacementPlugin(),
    new MiniCssExtractPlugin({
      // Options similar to the same options in webpackOptions.output
      // both options are optional
      filename: 'bundle.css',
      chunkFilename: '[id].css'
    })
  ],
};