jquery实现textarea发布框限制文字字数输入(添加中文识别)

<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.4.4/jquery.min.js"></script> 
<script type="text/javascript"> 
$(function() { 
$("textarea").keyup(); 
}); 

function strLenCalc(obj, checklen, maxlen) { 
　　var v = obj.val(), charlen = 0, maxlen = !maxlen ? 200 : maxlen, curlen = maxlen, len = v.length; 
　　for(var i = 0; i < v.length; i++) { 
　　　　if(v.charCodeAt(i) < 0 || v.charCodeAt(i) > 255) { 
curlen -= 1; 
} 
} 
　　if(curlen >= len) { 
$("#"+checklen).html("还可输入 <strong>"+Math.floor((curlen-len)/2)+"</strong> 个字").css('color', ''); 
$("#subBtn").removeAttr("disabled"); 
} else { 
$("#"+checklen).html("已经超过 <strong>"+Math.ceil((len-curlen)/2)+"</strong> 个字").css('color', '#FF0000'); 
$("#subBtn").attr("disabled", "disabled"); 
} 
} 
</script> 

<textarea tabindex="11" onkeyup="strLenCalc($(this), 'checklen', 80);" value="" class="px" name="subject" id="subject"></textarea> 
<span id="checklen">还可输入 <strong>40</strong> 个汉字</span> 
<input type="submit" id="subBtn" value="发布" />