Datetime comparison in JavaScript/jQuery

Question

I have these two calendar pickers that chooses the date for you, one for arrival and one of departed.

If the user chooses a day in departed calendar that is earlier than the one in arrival calendar, the calendar picker should be either disabled or when choosen - ignore it.

For example: arrival is 2017-03-08, choosen and read in the textbox and same for departed. If I try to pick 2017-03-07 for departed, it should not allow it and not be read in the textbox.

How is this possible with javascript/jquery?

My code:

var CalendarTwo;

function onPopupTxtArrivalDateChanged(sender) { //Function that reads arrival date
    var txtArrival = $("#txtArrivalDate");
    var date = new Date(sender.getSelectedDate());
    var textDate = date.getFullYear() + "-" + (date.getMonth() <= 9 ? "0" + (date.getMonth() + 1)
        : (date.getMonth() + 1)) + "-" + (date.getDate() <= 9 ? "0" + date.getDate() : date.getDate());

    txtArrival.val(textDate);
    onChange(sender, txtArrival, $("#txtDepartureDate")[0], CalendarTwo);
}

function onPopupTxtDepartureDateChanged(sender) { //Function that reads departed date
    var txtDeparture = $("#txtDepartureDate");
    var date = new Date(sender.getSelectedDate());
    var textDate = date.getFullYear() + "-" + (date.getMonth() <= 9 ? "0" + (date.getMonth() + 1)
        : (date.getMonth() + 1)) + "-" + (date.getDate() <= 9 ? "0" + date.getDate() : date.getDate());
    CalendarTwo = sender;
    txtDeparture.val(textDate);
}

function onChange(sender, txt, departed, calendarTwo) { //Function that checks that arrival date and departed is equal
    var txtDate = $(txt).val();
    var date = new Date(txtDate);
    if (departed != undefined) {
        CalendarTwo = calendarTwo;
        var departedDate = new Date($(departed).val());
        if (departedDate < date) {
            calendarTwo.setSelectedDate(date);
            departed.value = txtDate;
        }
    }

    sender.SetSelectedDate(date);
}