JQ限制输入字数，并提示剩余字数

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>jquery限制输入字数,并提示剩余字数</title>
<script type="text/javascript" src="jquery.js"></script>
<script type="text/javascript">
function words_deal()
{
   var curLength=$("#TextArea1").val().length;
   if(curLength>5)
   {
        var num=$("#TextArea1").val().substr(0,5);
        $("#TextArea1").val(num);
        alert("超过字数限制，多出的字将被截断！" );
   }
   else
   {
        $("#textCount").text(5-$("#TextArea1").val().length);
   }
}
</script>
</head>
<body>
剩余<span id="textCount">5</span>个字<br />
<textarea name="textarea" id="TextArea1" cols="45" rows="5" onkeyup="words_deal();" ></textarea>
</body>
</html>