$(document).on("scroll", function () {
 //真实内容的高度
 var pageHeight = Math.max(document.body.scrollHeight, document.body.offsetHeight);
 //视窗的高度
 var viewportHeight = window.innerHeight || document.documentElement.clientHeight || document.body.clientHeight || 0;
 //隐藏的高度
 var scrollHeight = window.pageYOffset || document.documentElement.scrollTop || document.body.scrollTop || 0;
 //判断加载视频，文章，回答，医生
 if(pageHeight - viewportHeight - scrollHeight <=0){
  //事件
 }
});