Add this to your page:
<script type="text/javascript">
var hideorshow="none"
function blinkImg(imgname) {
var obj = document.images['imgname']
obj.style.display=hideorshow
if (hideorshow=="block") { hideorshow="none" }
else { hideorshow="block" }
}
</script>
And add name="whatyouwanttocallit" to your image tag and call the JS function blinkImg('whatyoucalledtheimage') whenever you want it to blink.
That won't blink. It won't do anything because var obj = document.images['imgname'] will not represent any image passed to the function unless its name is literally 'imgname'. You should have left the quotes off. Even if it did 'work', it would take the image out of the page flow or put it into the page flow once and once only per execution, disrupting the flow of the document.
This works:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/1999/REC-html401-19991224/loose.dtd">
<html>
<head>
<title></title>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<script type="text/javascript">
var blinkImg = function (imgname, s) {
clearTimeout(blinkImg['blinking' + imgname]);
var obj = document.images[imgname];
if (arguments[1] === 'blink') {
obj.style.visibility = !(blinkImg[s + imgname] = !blinkImg[s + imgname])? '' : 'hidden';
blinkImg['blinking' + imgname] = setTimeout(function(){blinkImg(imgname, s);}, 350);
}
else {
blinkImg['blink' + imgname] = false;
obj.style.visibility = '';
}
};
</script>
</head>
<body>
<img name="blinker1" src="some.gif"><br>
<input type="button" onclick="blinkImg('blinker1', 'blink');" value="Blink">
<input type="button" onclick="blinkImg('blinker1', 'stop');" value="Stop">
</body>
</html>