gform.addFilter( 'gform_datepicker_options_pre_init', function( optionsObj, formId, fieldId ) { if ( formId == 12 && fieldId == 14 ) { var disabledDays = ['31/12/2022']; optionsObj.beforeShowDay = function(date) { var checkdate = jQuery.datepicker.formatDate('mm/dd/yy', date); return [disabledDays.indexOf(checkdate) == -1]; }; } return optionsObj; });