@procore/core-webpack/webpack.config.js

module.exports = {
  entry: './src/index.js',
  mode: 'development',
  devtool: 'source-map',
  module: {
    rules: [
      {
        test: /\.js$/,
        exclude: /node_modules/,
        use: ['babel-loader'],
      },
    ],
  },
}