webpack.config.js

module.exports = {
  entry: "./entry.js",
  output: {
    path: __dirname,
    filename: "bundle.js"
  },
  module: {
    loaders: [{
      test: /\.css$/,
      loader: "style!css"
    },{
      test: /\.js$/,
      loader: 'babel-loader'
    }]
  }
};