fullcalendar day toggle

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.10.6/moment.min.js"></script>
<script src="http://cdnjs.cloudflare.com/ajax/libs/fullcalendar/2.3.2/fullcalendar.min.js"></script>
<link rel="stylesheet" href="http://cdnjs.cloudflare.com/ajax/libs/fullcalendar/2.3.2/fullcalendar.min.css">
<br><h1>Click on days to toggle on and off</h1><br>
<div style="border:solid 1px red;">
    <div id='calendar'></div>
</div>

JavaScript

$(document).ready(function () {

    var date = new Date();
    var d = date.getDate();
    var m = date.getMonth();
    var y = date.getFullYear();

    var events_array = [{
        title: 'Test1',
        start: new Date(2018, 10, 20),
        tip: 'Personal tip 1'
    }, {
        title: 'Test2',
        start: new Date(2018, 10, 21),
        tip: 'Personal tip 2'
    }];

    $('#calendar').fullCalendar({
        header: {
            left: 'prev,next',
            center: 'title',
            right: 'today'
        },
        selectable: true,
        events: events_array,
        eventRender: function (event, element) {
            element.attr('title', event.tip);
        },
        dayClick: function (date, jsEvent, view) {

            // alert('Clicked on: ' + date.format());

            if ($(this).css('background-color') == 'rgb(102, 96, 55)') {
                //alert('on');
                $(this).css('background-color', 'rgb(255, 255, 255)');
            } else {
                //alert('off');
                $(this).css('background-color', 'rgb(102, 96, 55)');
            }
        }
    });
});