Webpack 2. Separate output for js files only?

Question

webpack

entry: {
    bundle: "./javascripts/bundle",
    babelPolyfill: 'babel-polyfill',
    commons: "./javascripts/commons",
    style: './stylesheets/style.scss'
  },
  output: {
    path: path.join(__dirname, 'public'),
    filename: '[name].js',
    publicPath: '/public/', 
  },

Why isn't js placed in the javascripts package on build?
How to make sure that only js files are placed there?
ExtractTextPlugin and fileloader work fine and everything is forwarded to the right place.
I thought to write to output And add to the rest of the loaders , but then the file-loader does not work. path: path.join(__dirname, 'public/javascripts'),
../