Utilize ScrollTop in conjunction with offset().top for scrolling to specific DIV nodes.
HTML
Ensure to assign an "active" class to the DIV element you want displayed first upon page load. In this case, it's the initial DIV item.
<button class="giu">Animate To Next available List Item</button>
<div class="product active" id="product1">1</div>
<div class="product" id="product2">2</div>
<div class="product" id="product3">3</div>
<div class="product" id="product4">4</div>
JavaScript
$('.giu').click(function(event) {
event.preventDefault();
var n = $(window).height();
$('div.active').removeClass('active').next('div').addClass('active');
$('body').animate({
scrollTop: $(".product.active").offset().top
}, 500);
});
Fiddle - http://jsfiddle.net/ideaovation/fhg1g974/3/