滚动触发页面（长页面）

<script type="text/javascript" src="../javascript/jquery-2.1.4.min.js"></script>
        
    
    
    
    
    <script type="text/javascript">
        $(document).ready(function(){
            $('#slogan1').addClass('show');
            
            var slogan2_y =$('#slogan2').offset().top;
            var slogan3_y=$('#slogan2').offset().top;
            
            var windowHeight = $(window).height();
            var buffer =200;
            $(window).scroll(function(){
                var pos =$(window).scrollTop();
                if(pos > slogan2_y-buffer){
                    $('#slogan2>h1').addClass('scrolled');
                    $('#slogan2>h2').addClass('scrolled');
                }
                
                if(pos>slogan3_y-buffer){
                    $('#slogan3>h1').addClass('scrolled');
                    $('#slogan3>h2').addClass('scrolled');
                    $('#slogan3>img').addClass('scrolled');
                }
                
                if(pos
   
    h1').removeClass('scrolled');
                    $('#slogan2>h2').removeClass('scrolled');
                }
                
                if(pos
    
     h1').removeClass('scrolled');
                    $('#slogan3>h2').removeClass('scrolled');
                    $('#slogan3>img').removeClass('scrolled');
                }
            });
            
            
            
            
        })
    </script>

    
        
     Done fringilla
Aenean cursus metus nec sem aliquet maximus in ut felis
Pellentesque
Aenean cursus metus nec sem aliquet maximus in ut felis
Vestibuilum
Aenean cursus metus nec sem aliquet maximus in ut felis