Check Year validation

function CheckDate($element) {
    if ($element.is('input:text')) {
        if ($element.val().trim() == "") {
            return;
        }
        if ($.inArray($element[0], objValidationFailed) === -1) {
            if (!$.validate($element.val().trim(), "isDate")) {
                validated = false;
                objValidationFailed.push($element[0]);
                $element.addClass('error');
            }
        }
    }
}