Added some small comments to widget code

IPython/html/static/notebook/js/widgetmanager.js

@@ -166,6 +166,7 b''
         };
 
         WidgetManager.prototype.get_model = function (model_id) {
+            // Look-up a model instance by its id.
             var model = this._models[model_id];
             if (model !== undefined && model.id == model_id) {
                 return model;
@@ -174,6 +175,7 b''
         };
 
         WidgetManager.prototype._handle_comm_open = function (comm, msg) {
+            // Handle when a comm is opened.
             var model_id = comm.comm_id;
             var widget_type_name = msg.content.target_name;
             var widget_model = new WidgetManager._model_types[widget_type_name](this, model_id, comm);

IPython/html/static/notebook/js/widgets/widget.js

@@ -132,6 +132,7 b' function(WidgetManager, Underscore, Backbone){'
         },
 
         sync: function (method, model, options) {
+            // Handle sync to the back-end.  Called when a model.save() is called.
 
             // Make sure a comm exists.
             var error = options.error || function() {
@@ -315,7 +316,6 b' function(WidgetManager, Underscore, Backbone){'
         touch: function () {
             this.model.save_changes(this.callbacks());
         },
-
     });