前端js上拉刷新获取数据问题

$( function(){
          var i=1;
        
         $(window).scroll( function(){
                  var scrollTop = 0;
                  var clientHeight = 0;
                  var scrollHeight = 0;
                  var replaceAppNo=$("input[name='replaceAppNo']" ).val();
                  if (document.documentElement && document.documentElement.scrollTop) {
                      scrollTop = document.documentElement.scrollTop;
                  } else if (document.body) {
                      scrollTop = document.body.scrollTop;
                  }
                  if (document.body.clientHeight && document.documentElement.clientHeight) {
                      clientHeight = (document.body.clientHeight < document.documentElement.clientHeight) ? document.body.clientHeight: document.documentElement.clientHeight;
                  } else {
                      clientHeight = (document.body.clientHeight > document.documentElement.clientHeight) ? document.body.clientHeight: document.documentElement.clientHeight;
                  }
                  scrollHeight = Math.max(document.body.scrollHeight, document.documentElement.scrollHeight);
                  if (scrollTop + clientHeight == scrollHeight) {           
                      $.getJSON("*****Action_getAjaxList.action" ,{page:i,replace_App_No:replaceAppNo},function(json){                
                            $.each(json, function(n,value){
                                    var trs = "" ;
                                   trs += "<tr><td align='center'><input type='checkbox'></td><td align='center'>"+(value.quaNo== undefined?'' :value.quaNo)+"</td><td align='center'>"+(value.chaVin== undefined?'' :value.chaVin)+"</td><td align='center'>"+(value.prdModelNo== undefined?'' :value.prdModelNo)+"</td><td width='10%' align='right'>"+value.quaMone+ "</td><td align='center'>"+(value.facDate== undefined?'' :value.facDate)+"</td><td align='center'>"+(value.accDate== undefined?'' :value.accDate)+"</td><td width='6%' align='center'>"+(value.cerType== undefined?'' :value.cerType)+"</td><td align='center'>"+(value.brandNo== undefined?'' :value.brandNo)+"</td></tr>";
                                   $( "#tablist tr:last" ).after(trs);
                            });
                      });
                      i++;
                  }
         });