صورة تتحرك الى أعلى و أسفل الشاشة و تقف عند الضغط عليها

<div id="img" style="position:absolute;">
<img src="SSSS.gif" onClick="pause_resume();" alt="دليل العرب الشامل">
</div>

<script language="JavaScript">
// Original: Justin Arruda (JArruda@mindspring.com)
// This script and many more are available free online at
// The JavaScript Source!! http://javascript.internet.com
//* Visit http://www.star28.com/ for more code

var xPos = 20;
var yPos = document.body.clientHeight;
var step = 1;
var delay = 30;
var height = 0;
var Hoffset = 0;
var Woffset = 0;
var yon = 0;
var xon = 0;
var pause = true;
var interval;
img.style.top = yPos;
function changePos() {
width = document.body.clientWidth;
height = document.body.clientHeight;
Hoffset = img.offsetHeight;
Woffset = img.offsetWidth;
img.style.left = xPos + document.body.scrollLeft;
img.style.top = yPos + document.body.scrollTop;
if (yon) {
yPos = yPos + step;
}
else {
yPos = yPos - step;
}
if (yPos < 0) {
yon = 1;
yPos = 0;
}
if (yPos >= (height - Hoffset)) {
yon = 0;
yPos = (height - Hoffset);
}
if (xon) {
xPos = xPos + step;
}
else {
xPos = xPos - step;
}
if (xPos < 0) {
xon = 1;
xPos = 0;
}
if (xPos >= (width - Woffset)) {
xon = 0;
xPos = (width - Woffset);
}
}
function start() {
img.visibility = "visible";
interval = setInterval('changePos()', delay);
}
function pause_resume() {
if(pause) {
clearInterval(interval);
pause = false;
}
else {
interval = setInterval('changePos()',delay);
pause = true;
}
}
start();
</script>
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