angular-translate: useStaticFilesLoader()

angular.module('myApp', ['pascalprecht.translate', 'ngCookies']);

angular.module('myApp').config(['$translateProvider',
  function($translateProvider) {
    var language = (window.navigator.userLanguage || window.navigator.language).toLowerCase();
    console.log(language);
    $translateProvider.registerAvailableLanguageKeys(['de_DE', 'en_US'], {
    'en_US': 'en_US',
    'en_UK': 'en_US',
    'en': 'en_US',
    'de': 'de_DE'
    });

    $translateProvider.useStaticFilesLoader({
      prefix: 'lang_',
      suffix: '.json'
    });


    $translateProvider.preferredLanguage('de_DE');
    // $translateProvider.use('de');
    $translateProvider.useCookieStorage();
    $translateProvider.fallbackLanguage("en_US");
  }
]);

angular.module('myApp').controller('someController', ['$scope', '$translate',
  function($scope, $translate) {

    $scope.switchLanguage = function(key) {
      $translate.use(key);
    };
  }
]);

<!doctype html>
<html ng-app="myApp">

<head>
  <meta charset="utf-8">
  <title>AngularJS Plunker</title>
  <script>
    document.write('<base href="' + document.location + '" />');
  </script>
  <link rel="stylesheet" href="style.css">
  <script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.3.14/angular.js"></script>
  <script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.3.14/angular-cookies.js"></script>
  <script src="https://rawgithub.com/angular-translate/bower-angular-translate/master/angular-translate.min.js"></script>
  <script src="https://rawgithub.com/angular-translate/bower-angular-translate-storage-cookie/master/angular-translate-storage-cookie.js"></script>
  <script src="https://rawgithub.com/angular-translate/bower-angular-translate-loader-static-files/master/angular-translate-loader-static-files.js"></script>
  <script src="app.js"></script>
</head>

<body ng-controller="someController">
  <h1 translate>HEADLINE</h1>
  <button ng-click="switchLanguage('de_DE')" translate="LANG_DE_DE"></button>
  <button ng-click="switchLanguage('en_US')" translate="LANG_EN_US"></button>
</body>

</html>

/* Put your css in here */

{
 "HEADLINE": "Hello da!",
 "LANG_DE_DE": "Sprache: Deutsch",
 "LANG_EN_US": "Sprache: Englisch"
}

{
 "HEADLINE": "Hello there!",
 "LANG_DE_DE": "Lang: German",
 "LANG_EN_US": "Lang: English"
}