frontend: level validation

templates/utils/isNumber.ts

@@ -0,0 +1,23 @@
+/*
+ * Copyright (C) 2021  Aravinth Manivannan <realaravinth@batsense.net>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+const isNumber = (value: string) => {
+  value = value.toString();
+  return /^\d+$/.test(value);
+};
+
+export default isNumber;