fix sessionStorage activeTab for ios

app/index.html

@@ -212,19 +212,25 @@
 <script>
     $(document).ready(function() {
         $("#footer").load("main-footer.html", function() {
-            if (!sessionStorage.activeTab) {
-                CHK.loadDashboardSetting(function() {
-                    if (CHK.dashboardSetting.dashboardHome) {
-                        CHK_Footer.goDashboard();
-                    } else {
-                        CHK_Footer.goOperationList();
-                    }
-                });
-            } else if (sessionStorage.activeTab === 'dashboard') {
-                CHK_Footer.goDashboard();
-            } else if (sessionStorage.activeTab === 'operationList') {
-                CHK_Footer.goOperationList();
+            let activeTab;
+            if (typeof sessionStorage != 'undefined' && sessionStorage.activeTab != 'undefined') {
+                activeTab = sessionStorage.activeTab;
             }
+            if (typeof activeTab != 'undefined') {
+                if (activeTab == 'dashboard') {
+                    CHK_Footer.goDashboard();
+                } else {
+                    CHK_Footer.goOperationList();
+                }
+                return;
+            }
+            CHK.loadDashboardSetting(function() {
+                if (CHK.dashboardSetting.dashboardHome) {
+                    CHK_Footer.goDashboard();
+                } else {
+                    CHK_Footer.goOperationList();
+                }
+            });
         });
     });
 </script>