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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<title>Countdown Demo</title>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<script>
for(var i=0;i<15;i++)
setTimeout("foo('"+i+"')",(15-i)*1000);
function foo(n){
document.getElementById('btn').value='Continue ('+n+')';
if(n==0){
document.getElementById('btn').value='Continue';
document.getElementById('btn').disabled=false;
}
}
</script>

<body>

<input id='btn' type='submit' value='Continue (15)' disabled='disabled' style="width:400 px;">

</body>
</html>