webpack.config.js

var webpack = require('webpack');
const prod = process.argv.indexOf('-p') !== -1;

var HtmlWebpackPlugin = require('html-webpack-plugin')
var HTMLWebpackPluginConfig = new HtmlWebpackPlugin({
  template: __dirname + '/app/index.html',
  filename: 'index.html',
  inject: 'body'
});

module.exports = {
  entry: [
    './app/index.js'
  ],
  resolve: {
    extensions: ['', '.js', '.jsx']
  },
  output: {
    path: __dirname + '/dist',
    filename: "index_bundle.js"
  },
  module: {
    loaders: [
      {
        test: /\.jsx?$/,
        loaders: [
          'babel?presets[]=react,presets[]=es2015',
        ]
      },
      {test: /\.js$/, exclude: /node_modules/, loader: "babel-loader"},
      { test: /\.css$/, loader: "style-loader!css-loader" }
    ]
  },
  plugins: [
      HTMLWebpackPluginConfig,
      new webpack.DefinePlugin({
          process: {
            env: {
              NODE_ENV: prod? `"production"`: '"development"'
            }
          }
        }),
    ]
};