JS 鼠标拖动效果实现

相对于鼠标拖动面板跟随变动效果，废话不多说了，具体代码：
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>鼠标拖动</title>
 <meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<script language="JavaScript" type="text/javascript">
var drag_=false
var D=new Function('obj','return document.getElementById(obj);')
var oevent=new Function('e','if (!e) e = window.event;return e')
function Move_obj(obj){
 var x,y;
 D(obj).onmousedown=function(e){
  drag_=true;
  with(this){
   style.position="absolute";var temp1=offsetLeft;var temp2=offsetTop;
   x=oevent(e).clientX;y=oevent(e).clientY;
   document.onmousemove=function(e){
    if(!drag_)return false;
    with(this){
     style.left=temp1+oevent(e).clientX-x+"px";
     style.top=temp2+oevent(e).clientY-y+"px";
    }
   }
  }
  document.onmouseup=new Function("drag_=false");
 }
}
</script>
<body>
<div id="drag" style="background-color:#0066CC;280px;height:160px;padding:20px;border:1px #003399 solid;font-size:10.5pt;color:white" onmouseover='Move_obj("drag")'>
  <p>这个层是可以拖动的，而且还可以吸附鼠标，试试看！</p>
  <p>/</p>
</div>
</body>
</html>