main.js

// placed in /src folder
import 'babel-polyfill';

const rsLowerC = `[a-c\\xdf-\\xf6]`;
const rsUpperC = `[A-C\\xc0-\\xd6]`;
const working1 = rsLowerC + '+' + '(?=' + rsUpperC + ')';
const reWorking1 = RegExp(working1, 'g');

const rsLowerZ = `[a-z\\xdf-\\xf6]`;
const rsUpperZ = `[A-Z\\xc0-\\xd6]`;
const notWorking = rsLowerZ + '+' + '(?=' + [rsUpperZ].join('|') + ')';
const reNotWorking = RegExp(notWorking, 'g');

console.log('success');

webpack.config.js

const BabiliPlugin = require('babili-webpack-plugin');
const path = require('path');

module.exports = {
  entry: './src/main.js',
  output: {
    path: path.join(__dirname, 'assets'),
    filename: 'main.bundle.js',
    library: 'main'
  },
  plugins: [
    new BabiliPlugin(
      {
        // evaluate: false
      }
    )
  ],
  module: {
    rules: [
      {
        test: /\.js$/,
        exclude: /node_modules/,
        loader: 'babel-loader',
        options: {
          presets: [['env']]
        }
      }
    ]
  }
};