webpack.config.js

module.exports = {
  devtool: 'cheap-module-source-map', // might want to change this `source-map` for prod builds
  entry: './entry',
  output: {
    path: './build',
    pathinfo: true,
    filename: 'bundle.js',
  },
  resolve: {
    // These are the reasonable defaults supported by the Node ecosystem.
    extensions: ['.js', '.json', ''],
  },
  module: {
    loaders: [
      // Process JS with Babel.
      {
        test: /\.js$/,
        include: './src',
        loader: 'babel-loader',
        query: { cacheDirectory: true }
      },
    ]
  },
  plugins: []
};