Create Textarea with maxlength validation

<script type="text/javascript">    
  function textCounter(fieldstr, countfieldstr, maxlimit){
    field =  document.getElementById(fieldstr);
    countfield = document.getElementById(countfieldstr);
    
    if (field.value.length > maxlimit) { 
      // if too long, trim it!
      field.value = field.value.substring(0, maxlimit);
    } else {
      // update 'characters left' counter
      countfield.value = maxlimit - field.value.length;
    }
  }
</script>

<h:form id="myform">
    <h:inputTextarea id="myarea"
          onkeydown="textCounter('myform:myarea','myform:myarea_remline',100);" 
          onkeyup="textCounter('myform:myarea','myform:myarea_remline',100);"
          onfocus="textCounter('myform:myarea','myform:myarea_remline',100);"
          disabled="#{disabled}"/>
    <br/>
    <h:inputText id="myarea_remline" value="100" size="4" maxlength="4" disabled="true"/> characters remaining
</h:form>