add utils: date conversion

frontend/src/lib/utils/utils.js

@@ -68,13 +68,20 @@ export function isEmpty(obj) {
   }
   return true;
 }
+
 /**
- * Test whether or not an object is empty.
+ * @typedef {Object} FormattedError
+ * @property {string} error - The error message
+ * @property {number} id - A unique identifier for the error
+ */
+/**
+ * Format Error object(s)
  * @param {any} obj - The object to test
- * @returns `true` or `false`
+ * @returns @type {FormattedError[]}
  */
 
 export function formatError(obj) {
+  /** @type {FormattedError[]} */
   const errors = [];
   if (typeof obj === "object" && obj !== null) {
     if (Array.isArray(obj)) {
@@ -103,3 +110,9 @@ export function formatError(obj) {
 
   return errors;
 }
+
+export function toRFC3339(dateString) {
+  if (!dateString) return "";
+  const date = new Date(dateString);
+  return date.toISOString();
+}