$(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     } });