用js实现分享到随页面滚动而滑动效果

页面向上向下滚动，分享到的模块随着滑动。

要点：

var scrtop =document.documentElement.scrollTop||document.body.scrollTop;
var height = document.documentElement.clientHeight||document.body.clientHeight;
var top = scrtop + (height - share.offsetHeight)/2;
top = parseInt(top);

获得页面垂直居中的位置

 

上代码：

<!DOCTYPE html>
<html>
<head>
<meta charset="gb2312" />
<title>无标题文档</title>
<style>
body{margin:0; padding:0; font:12px/1.5 arial; height:2000px;}
#share{width:100px; height:200px; line-height:200px; text-align:center; border:1p solid #ccc; background:#f5f5f5; position:absolute; left:-100px; top:0;}
#share_tit{position:absolute; right:-20px; top:60px; width:20px; height:60px; padding:10px 0; background:#06c; text-align:center; line-height:18px; color:#fff;}
</style>
<script>
/*jingangel http://www.cnblogs.com/jingangel/ */
window.onload = function(){
  var share = document.getElementById("share");
    share.onmouseover = function(){
      startrun(share,0,"left")
    }
    share.onmouseout = function(){
      startrun(share,-100,"left")
    }
        window.onscroll = window.onresize = function(){
            var scrtop =document.documentElement.scrollTop||document.body.scrollTop;
            var height = document.documentElement.clientHeight||document.body.clientHeight;
            var top = scrtop + (height - share.offsetHeight)/2;
            top = parseInt(top);
            startrun(share,top,"top")
        }
}

var timer = null
function startrun(obj,target,direction){
    clearInterval(timer);
    timer = setInterval(function(){
      var speed = 0;
        
                if(direction == "left"){
                    speed = (target-obj.offsetLeft)/8;
                    speed = speed>0?Math.ceil(speed):Math.floor(speed);
                    
                    if(obj.offsetLeft == target){
                        clearInterval(timer);
                    }else{
                        obj.style.left = obj.offsetLeft + speed + "px";
                    }
                }
                
                 if(direction == "top"){
                    speed = (target-obj.offsetTop)/8;
                    speed = speed>0?Math.ceil(speed):Math.floor(speed);
                    
                    if(obj.offsetTop == target){
                        clearInterval(timer);
                    }else{
                        obj.style.top = obj.offsetTop + speed + "px";
                    }
                    document.title = obj.offsetTop + ',' + target + ',' +speed;
                }
        
    },30)
}
</script>
</head>

<body>

<div id="share">
  分享到内容
  <span id="share_tit">分享到</span>
</div>

</body>
</html>



posted @ 2012-03-13 16:05  jingangel  阅读(2078)  评论(0)  编辑  收藏  举报