[AngularJS + Webpack] require directives

direictives/index.js:

module.exports = function(ngModule) {
    //register all the directives here
    require('./hello')(ngModule);
};

directives/hello.js

module.exports = function(ngModule) {
  ngModule.directive('webHello', function() {
      return {
          restrict: 'E',
          scope: {},
          templateUrl: 'directives/hello.html',
          controller: function() {
              var vm = this;

              vm.greeting = "Hello Webpack!";
          },
          controllerAs: 'vm'
      }
  })
};

directives/hello.html:

<h1>
    {{vm.greeting}}
</h1>

app/index.js:

var angular = require('angular');
var ngModule = angular.module('app', []);

//require directives folder, then it will find index.js file
require('./directives')(ngModule);

console.log(ngModule);

app/index.html:

<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title>Webpack + AngularJS</title>
</head>
<body ng-app="app">
    <web-hello></web-hello>
</body>
<script src="../build/bundle.js"></script>
</html>