JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="http://ajax.microsoft.com/ajax/jquery.ui/1.8.9/themes/start/jquery-ui.css">
<input type='text' id='txtDate' />

JavaScript

var unavailableDates = ["21-12-2011"];

function unavailable(date) {
    dmy = date.getDate() + "-" + (date.getMonth() + 1) + "-" + date.getFullYear();
    if ($.inArray(dmy, unavailableDates) == 0) {
        return [false, "", "Unavailable"];
    } else {
        return disabledays(date);
    }
}

function disabledays(date) {
    var day = date.getDay();
    return [(day != 0 && day != 2)];


}

$('#txtDate').datepicker({
    beforeShowDay: unavailable
})