webpack.config.js

'use strict';

const UglifyJsPlugin = require('uglifyjs-webpack-plugin');
var path = require('path');

process.env.NODE_ENV = 'development';

module.exports = {
  mode: 'development',
  entry: './src/index.js',
  output: {
    path: path.resolve(__dirname, 'build'),
    filename: 'index.js',
    libraryTarget: 'commonjs2',
  },
  module: {
    rules: [
      {
        test: /\.js$/,
        include: path.join(__dirname, 'src'),
        exclude: /(node_modules|build)/,
        use: ['babel-loader'],
      },
      {
        test: /\.css$/i,
        use: [
          'to-string-loader',
          'style-loader',
          'css-loader',
          'postcss-loader',
        ],
      },
    ],
  },
  optimization: {
    minimizer: [
      new UglifyJsPlugin({
        test: /\.js(\?.*)?$/i,
        extractComments: true,
        uglifyOptions: {
          warnings: false,
          parse: {},
          compress: {},
          mangle: true, // Note `mangle.properties` is `false` by default.
          output: null,
          toplevel: false,
          nameCache: null,
          ie8: false,
          keep_fnames: false,
        },
      }),
    ],
  },
};