<body>
<div id="float" style=" position:absolute; z-index:3">
<img id="img1" src="http://www.sharejs.com/images/logo.png" style=" border:1px #ccc solid" /><img id="img2" onClick="float.style.display='none'" src="关闭图片" style=" position:absolute; margin-left:-13px;" />
</div>
<script type="text/javascript">
var xPos=0;
var yPos=0;
var directionX=true;
var directionY=true;
var step=1;
var speed=1;
var float=document.getElementById("float");
function move(){
var height=document.documentElement.clientHeight;
var width=document.documentElement.clientWidth;
var imgHeight=float.offsetHeight;
var imgWidth=float.offsetWidth;
float.style.left=xPos+document.documentElement.scrollLeft+"px";
float.style.top=yPos+document.documentElement.scrollTop+"px";
if(directionX){xPos=xPos+step;}else{xPos=xPos-step;}
if(xPos<=0){xPos=0;directionX=true;}
if(xPos>=width-imgWidth){xPos=width-imgWidth;directionX=false;}
if(directionY){yPos=yPos+step;}else{yPos=yPos-step;}
if(yPos<=0){yPos=0;directionY=true;}
if(yPos>=height-imgHeight){yPos=height-imgHeight;directionY=false;}
t=setTimeout(move,speed);
}
float.onmouseover=function(){clearTimeout(t);}
float.onmouseout=function(){t=setTimeout("move()",speed);}
window.onload=move();
</script>
</body>
//javascript/8893