Execute function on defined vertical scroll position
$(window).scroll(function() {
var y_scroll_pos = window.pageYOffset;
var scroll_pos_test = 150;
// set to whatever you want it to be
if(y_scroll_pos > scroll_pos_test) {
$("body").css("background-color","#000");
}
else
{
$("body").css("background-color","#FFF");
}
});