Отображение лимита символов на форуме

<div onKeyUp="chklen()">  
$_MESSAGE$  
</div>  
Осталось символов: <input name="fcounter" type="text" class="codeButtons" size="6" value="20000" readonly="true">

<script language="JavaScript" type="text/javascript">  
function chklen()  
{  
max_limit=20000;  

str = document.addform.message.value;  
len = str.length;  

if (len > max_limit)  
{  
str = str.substring(0,max_limit);  
len = str.length;  
document.addform.message.value = str;  
}  

document.addform.fcounter.value = (max_limit - document.addform.message.value.length);  

while ( document.addform.fcounter.value<0)  
{  
document.addform.message.value = str.substring(0,len-1);  
str = document.addform.message.value;  
len = str.length;  
document.addform.fcounter.value = (max_limit - document.addform.message.value.length);  
}  
}  
</script>