<script >

var img= document.getElementById("img");

var x=0,y=0;

var xSpeed=5;
var ySpeed=5;

var w=document.body.clientWidth-111;
var h=document.body.clientHeight-111;

function floatimg(){

if(x>w||x<0) xSpeed=-xSpeed;
if(y>h||y<0) ySpeed=-ySpeed;

x+=xSpeed;
y+=ySpeed;


img.style.position='absolute';
img.style.left=x+"px";
img.style.top=y+"px";
alert(x +' '+y );
setTimeout("floatimg()",1000);
}
floatimg();
</script>