JSdoc added

frontend-js/src/main/js/gui/Panel.js

@@ -100,6 +100,10 @@ Panel.prototype.getPanelName = function () {
   return this._panelName;
 };
 
+/**
+ *
+ * @param {HTMLElement} element
+ */
 Panel.prototype.setElement = function (element) {
   if (element === undefined || element === null) {
     throw new Error("DOM Element must be defined");
@@ -107,6 +111,10 @@ Panel.prototype.setElement = function (element) {
   this._element = element;
 };
 
+/**
+ *
+ * @returns {HTMLElement}
+ */
 Panel.prototype.getElement = function () {
   return this._element;
 };