webpack.config.demo.js

const path = require('path');
const webpack = require('webpack');
const HtmlWebpackPlugin = require('html-webpack-plugin');

const PROD_MODE = process.env.NODE_ENV === 'production';

const entry = path.resolve(__dirname, 'demo/index.js');

const config = {
  entry: entry,
  output: {
    path: path.resolve(__dirname, 'build/'),
    filename: 'index.js',
  },
  module: {
    rules: [
      {
        test: /\.jsx?$/,
        include: [path.resolve(__dirname)],
        loader: 'babel-loader',
      },
      {
        test: /\.css$/,
        use: ['style-loader', 'css-loader'],
      },
    ],
  },
  plugins: [
    new webpack.DefinePlugin({
      'process.env': {
        NODE_ENV: JSON.stringify(PROD_MODE ? 'production' : 'development'),
      },
    }),
    new HtmlWebpackPlugin({
      template: './demo/index.html',
      filename: 'index.html',
      inject: 'body',
      chunksSortMode: 'dependency',
    }),
  ],
  devtool: false,
};

if (PROD_MODE) {
  const plugins = config.plugins;
  plugins.push(
    new webpack.optimize.UglifyJsPlugin({
      compress: {
        warnings: false,
        drop_console: true,
        dead_code: true,
        drop_debugger: true,
      },
      sourceMap: true,
      mangle: true,
    })
  );
}

module.exports = config;