minor changes

public/js/app.js

@@ -88193,9 +88193,10 @@ function (_Component) {
         margin: "5px"
       };
-      if (this.state.group == null) {
+      if (this.state.group == null || isNaN(userID)) {
         return null;
       } else {
+        console.log(userID);
         return react__WEBPACK_IMPORTED_MODULE_0___default.a.createElement("div", {
           style: mystyle
         }, react__WEBPACK_IMPORTED_MODULE_0___default.a.createElement("h2", null, "Add new class"), react__WEBPACK_IMPORTED_MODULE_0___default.a.createElement("form", {
@@ -88231,7 +88232,6 @@ function (_Component) {
       var _this6 = this;
       var content = document.getElementById('info');
-      content.innerHTML = "";
       var url = '/api/course/' + id;
       axios__WEBPACK_IMPORTED_MODULE_2___default.a.get(url).then(function (response) {
         console.log(response);
@@ -88241,6 +88241,7 @@ function (_Component) {
         });
         response.data.map(function (item) {
+          content.innerHTML = "";
           var h3 = document.createElement("h3");
           var pTime = document.createElement("p");
           var pDesc = document.createElement("p");

resources/js/components/Calendar.js

@@ -205,10 +205,11 @@ export default class Course extends Component {
         const eStyle = {
             margin: "5px"
         };
-        if(this.state.group == null){
+        if(this.state.group == null || isNaN(userID)){
             return null;
         }
         else {
+            console.log(userID);
             return (
                 <div style={mystyle}>
                 <h2>Add new class</h2>
@@ -239,7 +240,7 @@ export default class Course extends Component {
     showClass(id){
         
         var content = document.getElementById('info');
-        content.innerHTML = "";
+        
         let url = '/api/course/' + id;
         axios.get(url).then(response => {
             console.log(response);
@@ -247,6 +248,7 @@ export default class Course extends Component {
                 one: response.data
             });
             response.data.map(item =>{
+            content.innerHTML = "";
             var h3 = document.createElement("h3");
             var pTime = document.createElement("p");
             var pDesc = document.createElement("p");