Помогите разобраться со счетчиком

Есть счетчик времени.помогите разобраться как изменить дату отсчета на "до 31-го декабря осталось"

Менял дату в строке 'ts = new Date(2018, 12, 31)' но дата отображается некорректно.

(function($){
// Number of seconds in every time division
var days    = 24*60*60,
    hours   = 60*60,
    minutes = 60;
// Creating the plugin
$.fn.countdown = function(prop){
    var options = $.extend({
        callback    : function(){},
        timestamp   : 0
    },prop);
    var left, d, h, m, s, positions;
    // Initialize the plugin
    init(this, options);
    positions = this.find('.position');
    (function tick(){
        // Time left
        left = Math.floor((options.timestamp - (new Date())) / 1000);
        if(left < 0){
            left = 0;
        }
        // Number of days left
        d = Math.floor(left / days);
        updateDuo(0, 1, d);
        left -= d*days;
        // Number of hours left
        h = Math.floor(left / hours);
        updateDuo(2, 3, h);
        left -= h*hours;
        // Number of minutes left
        m = Math.floor(left / minutes);
        updateDuo(4, 5, m);
        left -= m*minutes;
        // Number of seconds left
        s = left;
        updateDuo(6, 7, s);
        // Calling an optional user supplied callback
        options.callback(d, h, m, s);
        // Scheduling another call of this function in 1s
        setTimeout(tick, 1000);
    })();
    // This function updates two digit positions at once
    function updateDuo(minor,major,value){
        switchDigit(positions.eq(minor),Math.floor(value/10)%10);
        switchDigit(positions.eq(major),value%10);
    }
    return this;
};

function init(elem, options){
    elem.addClass('countdownHolder');
    // Creating the markup inside the container
    $.each(['Days','Hours','Minutes','Seconds'],function(i){
        $('<span class="count'+this+'">').html(
            '<span class="position">\
                <span class="digit static">0</span>\
            </span>\
            <span class="position">\
                <span class="digit static">0</span>\
            </span>'
        ).appendTo(elem);
        if(this!="Seconds"){
            elem.append('<span class="countDiv countDiv'+i+'"></span>');
        }
    });
}
// Creates an animated transition between the two numbers
function switchDigit(position,number){
    var digit = position.find('.digit')
    if(digit.is(':animated')){
        return false;
    }
    if(position.data('digit') == number){
        // We are already showing this number
        return false;
    }
    position.data('digit', number);
    var replacement = $('<span>',{
        'class':'digit',
        css:{
            top:'-2.1em',
            opacity:0
        },
        html:number
    });
    // The .static class is added when the animation
    // completes. This makes it run smoother.
    digit
        .before(replacement)
        .removeClass('static')
        .animate({top:'2.5em',opacity:0},'fast',function(){
            digit.remove();
        })
    replacement
        .delay(100)
        .animate({top:0,opacity:1},'fast',function(){
            replacement.addClass('static');
        });
}
})(jQuery);
        </script>
        <script type="text/javascript">
$(function(){
var note = $('#note'),
    ts = new Date(2018, 12, 31),
    newYear = true;
if((new Date()) > ts){
    // The new year is here! Count towards something else.
    // Notice the *1000 at the end - time must be in milliseconds
    ts = (new Date()).getTime() + 0*0*00*00*1000;
    newYear = false;
}
$('#countdown').countdown({
    timestamp   : ts,
    callback    : function(days, hours, minutes, seconds){
        var message = "";
        message += days + " day" + ( days==1 ? '':'s' ) + ", ";
        message += hours + " hour" + ( hours==1 ? '':'s' ) + ", ";
        message += minutes + " minute" + ( minutes==1 ? '':'s' ) + " and ";
        message += seconds + " second" + ( seconds==1 ? '':'s' ) + " <br />";
        if(newYear){
            message += "left until the new year!";
        }
        else {
            message += "left to 10 days from now!";
        }
        note.html(message);
    }
});
});