var time1;
var srcollOld = 0,srcollNow = 0,scrollFun = false;
$(window).scroll(function () {
   //$(window).scrollTop()這個方法是當前滾動條滾動的距離
   //$(window).height()獲取當前窗體的高度
   //$(document).height()獲取當前文件的高度

    var bot = 50;  //bot是底部距離的高度
    if ((bot  +  $(window).scrollTop() )  >=  ($(document).height() - $(window).height())) {
          srcollNow = $(window).scrollTop();
          if(srcollNow >= srcollOld){
              if(!scrollFun){
              //第一次請求完成後才發第二次請求
                  scrollFun = true;
                  clearTimeout(time1);
                  time1=window.setTimeout(function(){
                      loadAjax()
                  },500);
              }
          }
          srcollOld = srcollNow;
      }
});

function loadAjax(){
    $.ajax({
        url: url,
        type: type,
        success:function (data) {
            scrollFun = false;
            if (data.success == true) {
            }else{
            }
        },
        error: function(XMLHttpRequest, textStatus, errorThrown) {
            scrollFun = false;
        }
    });
}