first commit

frontend/app/utils/function/projectDuration/index.tsx

@@ -0,0 +1,16 @@
+export function calculateDurationInDays(
+  startDate?: string | Date,
+  endDate?: string | Date
+): number | null {
+  if (!startDate || !endDate) return null;
+
+  const start = new Date(startDate);
+  const end = new Date(endDate);
+
+  if (isNaN(start.getTime()) || isNaN(end.getTime())) return null;
+
+  const diffTime = end.getTime() - start.getTime();
+  const diffDays = Math.ceil(diffTime / (1000 * 60 * 60 * 24));
+
+  return diffDays >= 0 ? diffDays : null;
+}