artplayer tool init

docs/thumbnail/js/common.js

@@ -0,0 +1 @@
+var thumbnail = new ArtplayerToolThumbnail('.artplayer-tool-thumbnail');

docs/uncompiled/artplayer-tool-thumbnail.js

@@ -19,6 +19,8 @@
     console.log(this);
   };
 
+  window.ArtplayerToolThumbnail = ArtplayerToolThumbnail;
+
   exports.default = ArtplayerToolThumbnail;
 
   Object.defineProperty(exports, '__esModule', { value: true });