ValidationErrorMessage Option - KidSysco/jquery-ui-month-picker GitHub Wiki

Type: Nullable String
Default: null
Sets the validation error message for use with text input types. Set to null to omit this behavior. This option will be ignored if the HTML 5 Input Type is used.

Set the option upon init.

$('.selector').MonthPicker({ ValidationErrorMessage: 'Invalid Date!' });

Get or set the option, after init.

//getter
var disabled = $('.selector').MonthPicker('option', 'ValidationErrorMessage');

//setter
$('.selector').MonthPicker('option', 'ValidationErrorMessage', null );