Webpack build commenting out bundle

Question

I use webpack with a very simple config:

module.exports = {
  entry: './index.js',
  output: {
    path: __dirname,
    filename: 'bundle.js'
  },
  module: {
    loaders: [

      {
        test: /\.jsx?$/,
        loader: 'babel',
        exclude: /node_modules/,
        query: {
          presets: [
            'es2015',
            'stage-0',
            'react'
          ]
        }
      }

    ]
  }
}

Running webpack or webpack-dev-server yields this bundle.js:

/******/ (function(modules) { // webpackBootstrap
/******/    // The module cache
/******/    var installedModules = {};

/******/    // The require function
/******/    function __webpack_require__(moduleId) {

/******/        // Check if module is in cache
/******/        if(installedModules[moduleId])
/******/            return installedModules[moduleId].exports;

/******/        // Create a new module (and put it into the cache)
/******/        var module = installedModules[moduleId] = {
/******/            exports: {},
/******/            id: moduleId,
/******/            loaded: false
/******/        };

/******/        // Execute the module function
/******/        modules[moduleId].call(module.exports, module, module.exports, __webpack_require__);

/******/        // Flag the module as loaded
/******/        module.loaded = true;

/******/        // Return the exports of the module
/******/        return module.exports;
/******/    }


/******/    // expose the modules object (__webpack_modules__)
/******/    __webpack_require__.m = modules;

/******/    // expose the module cache
/******/    __webpack_require__.c = installedModules;

/******/    // __webpack_public_path__
/******/    __webpack_require__.p = "";

/******/    // Load entry module and return exports
/******/    return __webpack_require__(0);
/******/ })
/************************************************************************/
/******/ ([
/* 0 */
/***/ function(module, exports) {

    'use strict';

    alert('test');

/***/ }
/******/ ]);

Where does these comments come from?

Answer 1

These comments come from Webpack itself. While webpack-dev-server will bundle your modules into folders, minification isn't applied when you're running webpack-dev-server . In production, when full minification is applied, these comments wouldn't be added.