jquery - getting multiple images when scrolling down a page -

i using code scrolling images when scrolling down multiple images displayed.

please can rectify issues, may problem if condition.

<script type="text/javascript">  $(document).ready(function(){      $(window).scroll(function(){         var windowheight = $(window).height();          //if($(window).scrolltop()+700 >= $(document).height() - windowheight)         if ($(window).scrolltop() >= ($(document).height() - $(window).height())*0.7){              $("#loader").html("<img src='http://www.niharonline.com/photo/ajax-loader.gif' alt='loading'/>");             var lastdiv = $(".as_country_container:last");              var lastid  = $(".as_country_container:last").attr("id");              var valuetopass = "lastid="+lastid;                          $.ajax({                  type: "post",                 url: "http://www.niharonline.com/photo/getdata.php",                 data: valuetopass,                 cache: true,           `enter code here`                 success: function(html){                                  if(html){                         lastdiv.after(html);                                   $('.columns-block').masonry('reload');                     }                 }             });         return false;         }     return false;     }); }); </script>