(function($) { var $animation_elements = $('.et-waypoint'), $window = $(window); function check_if_in_view() { var window_height = $window.height(), window_top_position = $window.scrollTop(), window_bottom_position = (window_top_position + window_height); $animation_elements.each(function() { var $element = $(this), element_height = $element.outerHeight(), element_top_position = $element.offset().top, element_bottom_position = (element_top_position + element_height); //check to see if this element is within viewport if ((element_bottom_position >= window_top_position) && (element_top_position <= window_bottom_position)) { $element.addClass('et-animated'); } else { $element.removeClass('et-animated'); } }); } $window.on('scroll resize', check_if_in_view); })(jQuery);