GLib.Date.valid_dmy

function valid_dmy(day: GLib.DateDay, month: GLib.DateMonth, year: GLib.DateYear): Boolean {
    // Gjs wrapper for g_date_valid_dmy()
}
  

Returns true if the day-month-year triplet forms a valid, existing day in the range of days GLib.Date understands (Year 1 or later, no more than a few thousand years in the future).