diff --git a/lib/videojs-resolution-switcher.js b/lib/videojs-resolution-switcher.js
index b23f3eb..b85db92 100644
--- a/lib/videojs-resolution-switcher.js
+++ b/lib/videojs-resolution-switcher.js
@@ -2,221 +2,231 @@
  * Copyright (c) 2015 Kasper Moskwiak
  * Modified by Pierre Kraft
  * Licensed under the Apache-2.0 license. */
-(function(window, videojs) {
-  /* jshint eqnull: true*/
-  'use strict';
 
-  var defaults = {},
-      videoJsResolutionSwitcher;
-
-  function setSourcesSanitized(player, sources) {
-    return player.src(sources.map(function(src) {
-      return {src: src.src, type: src.type, res: src.res};
-    }));
+(function() {
+  var videojs = null;
+  if(typeof window.videojs === 'undefined' && typeof require === 'function') {
+    videojs = require('videojs');
+  } else {
+    videojs = window.videojs;
   }
-
-  /*
-   * Resolution menu item
-   */
-  var MenuItem = videojs.getComponent('MenuItem');
-  var ResolutionMenuItem = videojs.extend(MenuItem, {
-    constructor: function(player, options, onClickListener, label){
-      this.onClickListener = onClickListener;
-      this.label = label;
-      // Sets this.player_, this.options_ and initializes the component
-      MenuItem.call(this, player, options);
-      this.src = options.src;
-
-      this.on('click', this.onClick);
-      this.on('touchstart', this.onClick);
-
-      if (options.initialySelected) {
-        this.showAsLabel();
-        this.selected(true);
-      }
-    },
-    showAsLabel: function() {
-      // Change menu button label to the label of this item if the menu button label is provided
-      if(this.label) {
-        this.label.innerHTML = this.options_.label;
-      }
-    },
-    onClick: function(){
-      this.onClickListener(this);
-      // Hide bigPlayButton
-      this.player_.bigPlayButton.hide();
-      // Remember player state
-      var currentTime = this.player_.currentTime();
-      var isPaused = this.player_.paused();
-      this.showAsLabel();
-      // Change player source and wait for loadeddata event, then play video
-      // loadedmetadata doesn't work right now for flash.
-      // Probably because of https://github.com/videojs/video-js-swf/issues/124
-      setSourcesSanitized(this.player_, this.src).one('loadeddata', function() {
-        this.player_.currentTime(currentTime);
-        if(!isPaused){
-          // Start playing and hide loadingSpinner (flash issue ?)
-          this.player_.play().handleTechSeeked_();
+   
+  (function(window, videojs) {
+    /* jshint eqnull: true*/
+    'use strict';
+  
+    var defaults = {},
+        videoJsResolutionSwitcher;
+  
+    function setSourcesSanitized(player, sources) {
+      return player.src(sources.map(function(src) {
+        return {src: src.src, type: src.type, res: src.res};
+      }));
+    }
+  
+    /*
+     * Resolution menu item
+     */
+    var MenuItem = videojs.getComponent('MenuItem');
+    var ResolutionMenuItem = videojs.extend(MenuItem, {
+      constructor: function(player, options, onClickListener, label){
+        this.onClickListener = onClickListener;
+        this.label = label;
+        // Sets this.player_, this.options_ and initializes the component
+        MenuItem.call(this, player, options);
+        this.src = options.src;
+  
+        this.on('click', this.onClick);
+        this.on('touchstart', this.onClick);
+  
+        if (options.initialySelected) {
+          this.showAsLabel();
+          this.selected(true);
         }
-        this.player_.trigger('resolutionchange');
-      });
-    }
-  });
-
-
-  /*
-   * Resolution menu button
-   */
-   var MenuButton = videojs.getComponent('MenuButton');
-   var ResolutionMenuButton = videojs.extend(MenuButton, {
-     constructor: function(player, options, settings, label){
-      this.sources = options.sources;
-      this.label = label;
-      this.label.innerHTML = options.initialySelectedLabel;
-      // Sets this.player_, this.options_ and initializes the component
-      MenuButton.call(this, player, options);
-      this.controlText('Quality');
-
-      if(settings.dynamicLabel){
-        this.el().appendChild(label);
-      }else{
-        var staticLabel = document.createElement('span');
-        staticLabel.classList.add('vjs-resolution-button-staticlabel');
-        this.el().appendChild(staticLabel);
-      }
-     },
-     createItems: function(){
-       var menuItems = [];
-       var labels = (this.sources && this.sources.label) || {};
-       var onClickUnselectOthers = function(clickedItem) {
-        menuItems.map(function(item) {
-          item.selected(item === clickedItem);
-        });
-       };
-
-       for (var key in labels) {
-         if (labels.hasOwnProperty(key)) {
-          menuItems.push(new ResolutionMenuItem(
-            this.player_,
-            {
-              label: key,
-              src: labels[key],
-              initialySelected: key === this.options_.initialySelectedLabel
-            },
-            onClickUnselectOthers,
-            this.label));
+      },
+      showAsLabel: function() {
+        // Change menu button label to the label of this item if the menu button label is provided
+        if(this.label) {
+          this.label.innerHTML = this.options_.label;
+        }
+      },
+      onClick: function(){
+        this.onClickListener(this);
+        // Hide bigPlayButton
+        this.player_.bigPlayButton.hide();
+        // Remember player state
+        var currentTime = this.player_.currentTime();
+        var isPaused = this.player_.paused();
+        this.showAsLabel();
+        // Change player source and wait for loadeddata event, then play video
+        // loadedmetadata doesn't work right now for flash.
+        // Probably because of https://github.com/videojs/video-js-swf/issues/124
+        setSourcesSanitized(this.player_, this.src).one('loadeddata', function() {
+          this.player_.currentTime(currentTime);
+          if(!isPaused){
+            // Start playing and hide loadingSpinner (flash issue ?)
+            this.player_.play().handleTechSeeked_();
           }
+          this.player_.trigger('resolutionchange');
+        });
+      }
+    });
+  
+  
+    /*
+     * Resolution menu button
+     */
+     var MenuButton = videojs.getComponent('MenuButton');
+     var ResolutionMenuButton = videojs.extend(MenuButton, {
+       constructor: function(player, options, settings, label){
+        this.sources = options.sources;
+        this.label = label;
+        this.label.innerHTML = options.initialySelectedLabel;
+        // Sets this.player_, this.options_ and initializes the component
+        MenuButton.call(this, player, options);
+        this.controlText('Quality');
+  
+        if(settings.dynamicLabel){
+          this.el().appendChild(label);
+        }else{
+          var staticLabel = document.createElement('span');
+          staticLabel.classList.add('vjs-resolution-button-staticlabel');
+          this.el().appendChild(staticLabel);
+        }
+       },
+       createItems: function(){
+         var menuItems = [];
+         var labels = (this.sources && this.sources.label) || {};
+         var onClickUnselectOthers = function(clickedItem) {
+          menuItems.map(function(item) {
+            item.selected(item === clickedItem);
+          });
+         };
+  
+         for (var key in labels) {
+           if (labels.hasOwnProperty(key)) {
+            menuItems.push(new ResolutionMenuItem(
+              this.player_,
+              {
+                label: key,
+                src: labels[key],
+                initialySelected: key === this.options_.initialySelectedLabel
+              },
+              onClickUnselectOthers,
+              this.label));
+            }
+         }
+         return menuItems;
        }
-       return menuItems;
-     }
-   });
-
-  /**
-   * Initialize the plugin.
-   * @param options (optional) {object} configuration for the plugin
-   */
-  videoJsResolutionSwitcher = function(options) {
-    var settings = videojs.mergeOptions(defaults, options),
-        player = this,
-        label = document.createElement('span');
-
-    label.classList.add('vjs-resolution-button-label');
-
-    player.updateSrc = function(src){
-      //Return current src if src is not given
-      if(!src){ return player.src(); }
-      // Dispose old resolution menu button before adding new sources
-      if(player.controlBar.resolutionSwitcher){
-        player.controlBar.resolutionSwitcher.dispose();
-        delete player.controlBar.resolutionSwitcher;
-      }
-      //Sort sources
-      src = src.sort(compareResolutions);
-      var groupedSrc = bucketSources(src);
-      var choosen = chooseSrc(groupedSrc, src);
-      var menuButton = new ResolutionMenuButton(player, { sources: groupedSrc, initialySelectedLabel: choosen.label , initialySelectedRes: choosen.res}, settings, label);
-      menuButton.el().classList.add('vjs-resolution-button');
-      player.controlBar.resolutionSwitcher = player.controlBar.addChild(menuButton);
-      return setSourcesSanitized(player, choosen.sources);
-    };
-
+     });
+  
     /**
-     * Method used for sorting list of sources
-     * @param   {Object} a source object with res property
-     * @param   {Object} b source object with res property
-     * @returns {Number} result of comparation
+     * Initialize the plugin.
+     * @param options (optional) {object} configuration for the plugin
      */
-    function compareResolutions(a, b){
-      if(!a.res || !b.res){ return 0; }
-      return (+b.res)-(+a.res);
-    }
-
-    /**
-     * Group sources by label, resolution and type
-     * @param   {Array}  src Array of sources
-     * @returns {Object} grouped sources: { label: { key: [] }, res: { key: [] }, type: { key: [] } }
-     */
-    function bucketSources(src){
-      var resolutions = {
-        label: {},
-        res: {},
-        type: {}
+    videoJsResolutionSwitcher = function(options) {
+      var settings = videojs.mergeOptions(defaults, options),
+          player = this,
+          label = document.createElement('span');
+  
+      label.classList.add('vjs-resolution-button-label');
+  
+      player.updateSrc = function(src){
+        //Return current src if src is not given
+        if(!src){ return player.src(); }
+        // Dispose old resolution menu button before adding new sources
+        if(player.controlBar.resolutionSwitcher){
+          player.controlBar.resolutionSwitcher.dispose();
+          delete player.controlBar.resolutionSwitcher;
+        }
+        //Sort sources
+        src = src.sort(compareResolutions);
+        var groupedSrc = bucketSources(src);
+        var choosen = chooseSrc(groupedSrc, src);
+        var menuButton = new ResolutionMenuButton(player, { sources: groupedSrc, initialySelectedLabel: choosen.label , initialySelectedRes: choosen.res}, settings, label);
+        menuButton.el().classList.add('vjs-resolution-button');
+        player.controlBar.resolutionSwitcher = player.controlBar.addChild(menuButton);
+        return setSourcesSanitized(player, choosen.sources);
       };
-      src.map(function(source) {
-        initResolutionKey(resolutions, 'label', source);
-        initResolutionKey(resolutions, 'res', source);
-        initResolutionKey(resolutions, 'type', source);
-
-        appendSourceToKey(resolutions, 'label', source);
-        appendSourceToKey(resolutions, 'res', source);
-        appendSourceToKey(resolutions, 'type', source);
-      });
-      return resolutions;
-    }
-
-    function initResolutionKey(resolutions, key, source) {
-      if(resolutions[key][source[key]] == null) {
-        resolutions[key][source[key]] = [];
+  
+      /**
+       * Method used for sorting list of sources
+       * @param   {Object} a source object with res property
+       * @param   {Object} b source object with res property
+       * @returns {Number} result of comparation
+       */
+      function compareResolutions(a, b){
+        if(!a.res || !b.res){ return 0; }
+        return (+b.res)-(+a.res);
       }
-    }
-
-    function appendSourceToKey(resolutions, key, source) {
-      resolutions[key][source[key]].push(source);
-    }
-
-    /**
-     * Choose src if option.default is specified
-     * @param   {Object} groupedSrc {res: { key: [] }}
-     * @param   {Array}  src Array of sources sorted by resolution used to find high and low res
-     * @returns {Object} {res: string, sources: []}
-     */
-    function chooseSrc(groupedSrc, src){
-      var selectedRes = settings.default;
-      var selectedLabel = '';
-      if (selectedRes === 'high') {
-        selectedRes = src[0].res;
-        selectedLabel = src[0].label;
-      } else if (selectedRes === 'low' || selectedRes == null) {
-        // Select low-res if default is low or not set
-        selectedRes = src[src.length - 1].res;
-        selectedLabel = src[src.length -1].label;
-      } else if (groupedSrc.res[selectedRes]) {
-        selectedLabel = groupedSrc.res[selectedRes][0].label;
+  
+      /**
+       * Group sources by label, resolution and type
+       * @param   {Array}  src Array of sources
+       * @returns {Object} grouped sources: { label: { key: [] }, res: { key: [] }, type: { key: [] } }
+       */
+      function bucketSources(src){
+        var resolutions = {
+          label: {},
+          res: {},
+          type: {}
+        };
+        src.map(function(source) {
+          initResolutionKey(resolutions, 'label', source);
+          initResolutionKey(resolutions, 'res', source);
+          initResolutionKey(resolutions, 'type', source);
+  
+          appendSourceToKey(resolutions, 'label', source);
+          appendSourceToKey(resolutions, 'res', source);
+          appendSourceToKey(resolutions, 'type', source);
+        });
+        return resolutions;
       }
-      
-      if(selectedRes === undefined){
-        return {res: selectedRes, label: selectedLabel, sources: groupedSrc.label[selectedLabel]};
+  
+      function initResolutionKey(resolutions, key, source) {
+        if(resolutions[key][source[key]] == null) {
+          resolutions[key][source[key]] = [];
+        }
       }
-      return {res: selectedRes, label: selectedLabel, sources: groupedSrc.res[selectedRes]};
-    }
-
-    // Create resolution switcher for videos form <source> tag inside <video>
-    if(player.options_.sources.length > 1){
-      player.updateSrc(player.options_.sources);
-    }
-
-  };
-
-  // register the plugin
-  videojs.plugin('videoJsResolutionSwitcher', videoJsResolutionSwitcher);
-})(window, window.videojs);
+  
+      function appendSourceToKey(resolutions, key, source) {
+        resolutions[key][source[key]].push(source);
+      }
+  
+      /**
+       * Choose src if option.default is specified
+       * @param   {Object} groupedSrc {res: { key: [] }}
+       * @param   {Array}  src Array of sources sorted by resolution used to find high and low res
+       * @returns {Object} {res: string, sources: []}
+       */
+      function chooseSrc(groupedSrc, src){
+        var selectedRes = settings.default;
+        var selectedLabel = '';
+        if (selectedRes === 'high') {
+          selectedRes = src[0].res;
+          selectedLabel = src[0].label;
+        } else if (selectedRes === 'low' || selectedRes == null) {
+          // Select low-res if default is low or not set
+          selectedRes = src[src.length - 1].res;
+          selectedLabel = src[src.length -1].label;
+        } else if (groupedSrc.res[selectedRes]) {
+          selectedLabel = groupedSrc.res[selectedRes][0].label;
+        }
+        
+        if(selectedRes === undefined){
+          return {res: selectedRes, label: selectedLabel, sources: groupedSrc.label[selectedLabel]};
+        }
+        return {res: selectedRes, label: selectedLabel, sources: groupedSrc.res[selectedRes]};
+      }
+  
+      // Create resolution switcher for videos form <source> tag inside <video>
+      if(player.options_.sources.length > 1){
+        player.updateSrc(player.options_.sources);
+      }
+  
+    };
+  
+    // register the plugin
+    videojs.plugin('videoJsResolutionSwitcher', videoJsResolutionSwitcher);
+  })(window, videojs);
+})();