Regex for all date formats code example
Example 1: regex valid day
/^(0[1-9]|[12]\d|3[01])$/Example 2: regex datetime
\d{4}-[01]\d-[0-3]\dT[0-2]\d:[0-5]\d:[0-5]\d(?:\.\d+)?Z?/^(0[1-9]|[12]\d|3[01])$/\d{4}-[01]\d-[0-3]\dT[0-2]\d:[0-5]\d:[0-5]\d(?:\.\d+)?Z?