webpack.config.js

var webpack = require('webpack');
var path = require('path');

module.exports = {
  entry: getEntrySources(['./app/index.js']),
  output: {
    path: path.join(__dirname, 'dist'),
    publicPath: '/dist/',
    filename: 'bundle.js'
  },
  devtool: 'eval',
  plugins: [
    new webpack.HotModuleReplacementPlugin(),
  ],
  module: {
    preLoaders: [
      {
        test: /\.jsx?$/,
        exclude: /(node_modules|bower_components)/,
        loader: 'source-map'
      }
    ],
    loaders: [
      {
        test: /\.scss$/,
        include: /app/,
        loaders: [
          'style',
          'css',
          'autoprefixer?browsers=last 3 versions',
          'sass?outputStyle=expanded'
        ]
      },
      {
        test: /\.(jpe?g|png|gif|svg|woff|woff2|eot|ttf)$/i,
        loaders: [
          'url?limit=8192',
          'img'
        ]
      },
      {
        test: /\.jsx?$/,
        exclude: /(node_modules|bower_components)/,
        loaders: [
          'react-hot',
          'babel'
        ]
      }
    ]
  }
};

function getEntrySources(sources) {
    if (process.env.NODE_ENV !== 'production') {
        sources.push('webpack-dev-server/client?http://localhost:3000/');
        sources.push('webpack/hot/only-dev-server');
    }

    return sources;
}