JS 获取滚动条位置

function getScrollTop(){
var scrollTop=0;
if(document.documentElement&&document.documentElement.scrollTop){
scrollTop=document.documentElement.scrollTop;
}else if(document.body){
scrollTop=document.body.scrollTop;
}
return scrollTop;
}
document.onscroll = function(){
console.log(getScrollTop())
}