Adds javascript function for rendering a date according to user preference

InvenTree/templates/js/dynamic/calendar.js

@@ -7,6 +7,7 @@
     clearEvents,
     endDate,
     startDate,
+    renderDate,
 */
 
 /**
@@ -32,3 +33,29 @@ function clearEvents(calendar) {
         event.remove();
     });
 }
+
+
+/*
+ * Render the provided date in the user-specified format.
+ *
+ * The provided "date" variable is a string, nominally ISO format e.g. 2022-02-22
+ * The user-configured setting DATE_DISPLAY_FORMAT determines how the date should be displayed.
+ */
+
+function renderDate(date) {
+
+    if (!date) {
+        return null;
+    }
+
+    var fmt = user_settings.DATE_DISPLAY_FORMAT || 'YYYY-MM-DD';
+
+    var m = moment(date);
+
+    if (m.isValid()) {
+        return m.format(fmt);
+    } else {
+        // Invalid input string, simply return provided value
+        return date;
+    }
+}