Add/Remove class from element when element scrolls.
$(function(){
var addRemoveClass = 1;
$(window).scroll(function() {
var scroll = getCurrentScroll();
if ( scroll >= addRemoveClass ) {
$('.ELEMENT').addClass('CLASS');
}
else {
$('.ELEMENT').removeClass('CLASS');
}
});
function getCurrentScroll() {
return window.pageYOffset;
}
});