防止堆叠AJAX请求

Question

I've got a problem which I can't seem to solve.

I'm currently implementing a an AJAX-function similar to the one Twitter uses - that fetch new posts on scrolling.

The jQuery looks something like this:

        $(window).scroll(function(){
            if($(window).scrollTop() == $(document).height() - $(window).height()){
                $('div#ajaxloader').show();
                $.ajax({
                    url: "loader.php?lastid=" + $(".container:last").attr("id"),
                    success: function(html){
                        if(html){
                            $("#main").append(html);
                            $('div#ajaxloader').hide();
                        }else{
                            $('div#ajaxloader').html('No more posts to show.');
                        }
                    }                   
                });
            }
        });

Now the problem; if the user scrolls really fast and the database is doing it's work quickly - the jQuery doesn't seem to be able to send the correct id as a query fast enough - which results in double-posts.

Anyone have a good idea on how to prevent this?

Answer 1

Try This:

  var runningRequest = 0;
  $(window).scroll(function(){
        if(runningRequest <1){
        if($(window).scrollTop() == $(document).height() - $(window).height()){
            runningRequest++;
            $('div#ajaxloader').show();
            $.ajax({
                url: "loader.php?lastid=" + $(".container:last").attr("id"),
                success: function(html){
                    runningRequest--;
                    if(html){
                        $("#main").append(html);
                        $('div#ajaxloader').hide();
                    }else{
                        $('div#ajaxloader').html('No more posts to show.');
                    }
                }
                error: function(){runningRequest--;}                   
            });
        }
        }
    });