markup/js/script.js

var $positionAbsolute = $('#absolute').addClass('hide');
var $item = $('.hide-button').data('counter', 1);
var $changeBgPreviosly = $('#change-bg-previous');
var $changeBgNext = $('#change-bg-next');

var arr = [
		{
	'background': 'url(img/combo.jpg)',
	'background-color': 'rgba(0,0,0,0.3)',
	'background-blend-mode': 'multiply',
	'background-position': 'center',
	'background-repeat': 'no-repeat'
	},
		{
	'background': 'url(img/combo1.jpg)',
	'background-color': 'rgba(0,0,0,0.3)',
	'background-blend-mode': 'multiply',
	'background-position': 'center',
	'background-repeat': 'no-repeat'
	},
		{
	'background': 'url(img/combo2.jpg)',
	'background-color': 'rgba(0,0,0,0.3)',
	'background-blend-mode': 'multiply',
	'background-position': 'center',
	'background-repeat': 'no-repeat'
	},
		{
	'background': 'url(img/combo3.jpg)',
	'background-color': 'rgba(0,0,0,0.3)',
	'background-blend-mode': 'multiply',
	'background-position': 'center',
	'background-repeat': 'no-repeat'
	},
		{
	'background': 'url(img/combo4.jpg)',
	'background-color': 'rgba(0,0,0,0.3)',
	'background-blend-mode': 'multiply',
	'background-position': 'center',
	'background-repeat': 'no-repeat'
	},
		{
	'background': 'url(img/combo.jpg)',
	'background-color': 'rgba(0,0,0,0.3)',
	'background-blend-mode': 'multiply',
	'background-position': 'center',
	'background-repeat': 'no-repeat'
	},
];

var $background = $('#bg').css(arr[0]);
var carousel = setInterval(function() {
	$background.css(arr[ Math.floor((Math.random() * 5) + 1) ]);
}, 8000);


$item.on('click', function(event) {
	event.preventDefault();

	var counter = $item.data('counter');
	$item.data('counter', counter + 1);

	if (counter !== 0) {
		$positionAbsolute.removeClass('hide').addClass('show').text(counter);
	}
});

$changeBgPreviosly.on('click', function(){
	event.preventDefault();
	$background.css(arr[ Math.floor((Math.random() * 5) + 1) ]);
});

$changeBgNext.on('click', function(){
	event.preventDefault();
	$background.css(arr[ Math.floor((Math.random() * 5) + 1) ]);
});

$(window).scroll(function(){
	if ($(this).scrollTop() > 200) {
		$('.scrollup').fadeIn();
	} else {
		$('.scrollup').fadeOut();
	}
});
 $('.scrollup').click(function(){
	$("html, body").animate({ scrollTop: 0 }, 600);
});