webpack.config.js

const path = require('path');

module.exports = {
    entry: './src/index.js',
    output: {
        path: path.join(__dirname, '/public/js'),
        filename: 'bundle.js',
        libraryTarget: 'commonjs2'
    },
    module: {
        rules: [
            {
                test: /\.js$/,
                include: path.resolve(__dirname, 'src'),
                exclude: /(node_modules|bower_components|build)/,
                use: { loader: 'babel-loader' }
            }, {
                test: /\.css$/,
                use: [
                    "style-loader",
                    {
                        loader: "css-loader",
                        options: {
                            modules: true
                        }
                    }
                ]
            }
        ]
    },
    externals: {
        'react': 'commonjs react'
    }
};