回到顶部按钮 代码

 

<span class="scrolltop" onclick="window.scrollTo(0,0);">回到顶部</span>

<script language="javascript">
function GoTop() {
     window.scrollTo(0,0);
}
</script>

<span onclick="GoTop()" title="顶部">TOP</span>

//回到TOP代码
backTop=function (btnId){
var btn=document.getElementById(btnId);
var d=document.documentElement;
window.onscroll=set;
btn.onclick=function (){
btn.style.display="none";
window.onscroll=null;
this.timer=setInterval(function(){
d.scrollTop-=Math.ceil(d.scrollTop*0.1);
if(d.scrollTop==0) clearInterval(btn.timer,window.onscroll=set);
},10);
};
function set(){btn.style.display=d.scrollTop?'block':"none"}
};
backTop('goto_top');

<div id="goto_top">top</div>

 

 

 

 

 

/**
 * 回到页面顶部
 * @param acceleration 加速度
 * @param time 时间间隔 (毫秒)
 **/ function goTop(acceleration, time) {  acceleration = acceleration || 0.1;  time = time || 16;  
 var x1 = 0;  var y1 = 0;  var x2 = 0;  var y2 = 0;  var x3 = 0;  var y3 = 0;  
 if (document.documentElement) {   x1 = document.documentElement.scrollLeft || 0;   y1 = document.documentElement.scrollTop || 0;  }  if (document.body) {   x2 = document.body.scrollLeft || 0;   y2 = document.body.scrollTop || 0;  }  var x3 = window.scrollX || 0;  var y3 = window.scrollY || 0;  
 // 滚动条到页面顶部的水平距离  var x = Math.max(x1, Math.max(x2, x3));  // 滚动条到页面顶部的垂直距离  var y = Math.max(y1, Math.max(y2, y3));  
 // 滚动距离 = 目前距离 / 速度, 因为距离原来越小, 速度是大于 1 的数, 所以滚动距离会越来越小  var speed = 1 + acceleration;  window.scrollTo(Math.floor(x / speed), Math.floor(y / speed));  
 // 如果距离不为零, 继续调用迭代本函数  if(x > 0 || y > 0) {   var invokeFunction = "goTop(" + acceleration + ", " + time + ")";   window.setTimeout(invokeFunction, time);  } }

 

 

 

 

 

<a href="#" onclick="goTop();return false;">TOP</a>