//scrolltop垂直滚动条位置//onscroll 事件在元素滚动条在滚动时触发。var scrolltop=null;
window.onscroll=function(e){
var e=e;
scrolltop=document.documentElement.scrollTop;
if(scrolltop > 150){
document.getElementById("tb2").style.display="block";
}else{
document.getElementById("tb2").style.display="none";
}
}
转载于:https://www.cnblogs.com/tanchangsha/p/10223453.html
