package.json

{
  "name": "tmp",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "build": "webpack --config webpack.conf.js"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "devDependencies": {
    "babel-core": "^6.2.1",
    "babel-loader": "^6.2.0",
    "babel-preset-es2015": "^6.1.18",
    "babel-preset-react": "^6.1.18",
    "webpack": "^1.12.9"
  },
  "dependencies": {
    "react": "^0.14.3",
    "react-dom": "^0.14.3"
  }
}

webpack.conf.js

var path = require("path");
var build = path.resolve(__dirname, 'build/');
module.exports = {
    entry: path.join(__dirname, '/src/app.jsx'),
    resolve: {
      extensions: ["", ".js", ".jsx", ".txt"],
    },
    output: {
        path: build,
        filename: "app.js"
    },
    module: {
      loaders: [
        {
          test: /\.jsx?$/,
          exclude: /(node_modules|bower_components)/,
          include: path.join(__dirname, '/src/'),
          loader: 'babel?presets[]=react,presets[]=es2015'
        }
      ]
    }
};