Add date helper

lib/dateHelpers.ts

@@ -0,0 +1,16 @@
+const timestampFromDatetimeLocal = (datetimeLocal: string): number => {
+  const [date, time] = datetimeLocal.split("T");
+  const [year, month, day] = date.split("-");
+  const [hours, minutes] = time.split(":");
+
+  const dateObj = new Date(
+    Number(year),
+    Number(month) - 1,
+    Number(day),
+    Number(hours),
+    Number(minutes),
+  );
+  return Math.floor(dateObj.getTime() / 1000);
+};
+
+export { timestampFromDatetimeLocal };