webpack.config.js

// npm install webpack react reactdom babel-preset-react babel-core babel-loader
module.exports = {
    entry: './app.jsx',
    output: {
        path: './dist',
        filename: 'bundle.js'
    },
    module: {
        loaders: [{
            test: /\.jsx$/,
            exclude: /(node_modules|bower_components)/,
            loader: 'babel',
            query: {
                cacheDirectory: true,
                presets: ['react']
            }
        }]
    },
    externals: {
        'react': 'React',
        'react-dom': 'ReactDOM'
    },
    resolve: {
        extensions: ['', '.js', '.jsx']
    }
};