<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="content-type" charset="utf-8" />
<meta http-equiv="content-type" content="text/html" />
<title>demo</title>
</head>
<body>
<p>aaaaaaaaaaa</p>
<div id="one" style="height:100px;width:100px;background:red;position:absolute;"></div>
<script>
var odiv=document.getElementById("one");
dra(odiv);
function dra(obj){
obj.onmousedown=function(e){
var oe=e||window.event;
var $this=this;
var l=oe.clientX-$this.offsetLeft;
var t=oe.clientY-$this.offsetTop;
document.onmousemove=function(e){
var oe=e||window.event;
var ol=oe.clientX-l;
var ot=oe.clientY-t;
if(ol<0) ol=0;
if(ot<0) ot=0;
if(ot>document.documentElement.clientHeight-$this.offsetHeight) ot=document.documentElement.clientHeight-$this.offsetHeight;
if(ol>document.documentElement.clientWidth-$this.offsetWidth) ol=document.documentElement.clientWidth-$this.offsetWidth;
$this.style.left=ol+"px";
$this.style.top=ot+"px";
}
document.onmouseup=function(){
document.onmousemove=null;
document.onmouseup=null;
if($this.releaseCapture) $this.releaseCapture();
}
if($this.setCapture){
$this.setCapture();
}
if(oe.preventDefault) oe.preventDefault();
else oe.returnValue=false;
return false;
}
}
</script>
</body>
</html>
