javascript - Check for unseen posts and update title -

i need check wether user has seen post , change document title based on how many posts hasn't seen.

for example title 2 unseen posts: "(2) - post#123", or no unseen posts: "post #123".

i've looked couple of "scrolled view" jquery plugins, haven't found , quick solution ajaxed content (the posts appended div, checks new every 5 seconds).

so example markdown:

<div id="posts">  <div class="reply" data-postid="1" data-seen="no">  post 1  </div>  <div class="reply" data-postid="2" data-seen="no">  post 2  </div>  <div class="reply" data-postid="3" data-seen="no">  post 3  </div> </div> 

i'm guessing using attribute "seen" useful. how check if user has seen (the posts have been scrolled by/on screen) , store unseen in string use in title?

useful info: divs appended gotten via xhr, echoed out body of file "imported" or appended #posts xhr. name of function repeated every 5 seconds new posts postdata().

edit: i'm trying this, it's not working:

function isscrolledintoview(elem){ var docviewtop = $(window).scrolltop(); var docviewbottom = docviewtop + $(window).height();  var elemtop = $(elem).offset().top; var elembottom = elemtop + $(elem).height();  return ((elembottom <= docviewbottom) && (elemtop >= docviewtop)); }   $(window).scroll(function(){     isscrolledintoview(".reply[data-seen='no']", function(){         if ($(this) == true){             $(this).attr("data-seen", "yes");         }     }); }); 

updated working code (for bypassers):

function lescroll(){         var amount = "0";         $('.reply[data-seen="no"]').each(function(){             amount++;             if ( isscrolledintoview(this) ) {                 $(this).attr("data-seen", "yes");                 amount--;             };         });         document.title = "(" + amount + ") pagetitle";         if (amount == 0){             document.title = ">><?php echo($pageid); ?> - <?php echo($leboardname); ?> vikingchan";         }         settimeout(lescroll, 5000); /* make check while in tab */     }  $(window).scroll(function(){     lescroll(); }); $(document).ready(function(){     lescroll(); });  

to make code run elements change scroll callback

$(window).scroll(function(){     $('.reply[data-seen="no"]').each(function(){         if ( isscrolledintoview(this) ) {             $(this).attr("data-seen", "yes");         };     }); }); 

but keep in mind might bit heavy since scroll fired multiple times while scrolling. might want debounce scroll event.