change :

$(function () {
    $("#dp").datepicker({
        minDate: 0,
        dateFormat: 'mm/dd/yy',
        inline: true,
        numberOfMonths: [1, 2],
        dayNamesMin: ['Sun', 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat'],
        beforeShowDay: setCustomDate // <-----change function
    });
});

添加功能:

function setCustomDate(date) {
    var clazz = "";
    var arr1 = highlightDays(date);
    if (arr1[1] != "") clazz = arr1[1];

    var arr2 = disableAllTheseDays(date);
    var arr3 = $.datepicker.noWeekends(date);

    return [(!arr2[0] || !arr3[0]) ? false : true, clazz];
}