Salesforce - Displaying number of characters remaining on 'Text Area Field'

Solution – We need java script to implement

Java Script:  

 function size(fvalue, size, divid) {
       var input_field = document.getElementById(fvalue);
       var msg_count = document.getElementById(divid);
       var char_reamining = '0';
       var char_entered = input_field.value.length;  
       if(char_entered == 0){
        msg_count.innerHTML = '';
        msg_count.style.background = '#F7F7F7';
       }else {
       if(char_entered <= size){    
         char_reamining = size - char_entered;
         msg_count.innerHTML = char_reamining+ ' remaining';
         msg_count.style.background = 'yellow';
        }else{
          msg_count.innerHTML = char_reamining + ' remaining';
          msg_count.style.background = 'yellow';
          input_field.value = input_field.value.substring(0,size);   
      } } }

  VF Code:  

   <div id="msg" class="ErrorMessageClass">
   </div>
    <apex:inputField value="{!Case.Problem_Description__c}" style="width:900px" onkeyup="javascript:size('{!$Component.formId:pgBlockId:pbs1:tdescription}',10000,'msg');" id="tdescription" />

We are passing the id of custom field in function size as first parameter and as second parameter we are passing size of the custom field i.e. In above case we are passing the size as 10000 so at the point of first character it displays the message 9999 characters remaining and so on...and it doesn't allow to enter more than 10000 characters, as third parameter we are passing the id of div where we need to display the message.