To my knowledge, there is currently no built in function or method to count the number of cookies a user has on a domain. So I have devised this.

function countCookies(){
var totalcookies = 0;
var copycookie = document.cookie;
while(copycookie.match(/(\w+=.+?(;|$))/)){
totalcookies++;
copycookie = copycookie.replace(RegExp.$1,'');
}
return totalcookies;
}

It is as simple as:

<script type="text/javascript">
<!--
function countCookies(){
var totalcookies = 0;
var copycookie = document.cookie;
while(copycookie.match(/(\w+=.+?(;|$))/)){
totalcookies++;
copycookie = copycookie.replace(RegExp.$1,'');
}
return totalcookies;
}
alert(countCookies());
//-->
</script>