check if element got scrolled to top
You have to listen for the scroll event, then check each element against the currently scrolled distance, something like :
$(window).on('scroll', function() { var scrollTop = $(this).scrollTop(); $('.background1, .background2').each(function() { var topDistance = $(this).offset().top; if ( (topDistance+100) < scrollTop ) { alert( $(this).text() + ' was scrolled to the top' ); } });});