jQuery计算textarea中文字数(剩余个数)的小程序

代码如下:

<p class="area">
        <p>
            还可以输入<b class="num">140</b>字</p>
        <textarea class="chacktextarea"></textarea>
    </p>

 
<script type="text/javascript">
    var txtobj = {
        pname: "area", //外层容器的class
        textareaname: "chacktextarea", //textarea的class
        numname: "num", //数字的class
        num: 140 //数字的最大数目
    }
    var textareafn = function () {
        //定义变量
        var $onthis; //指向当前
        var $pname = txtobj.pname; //外层容器的class
        var $textareaname = txtobj.textareaname; //textarea的class
        var $numname = txtobj.numname; //数字的class
        var $num = txtobj.num; //数字的最大数目
        function ischinese(str) {  //判断是不是中文
            var rech = /[u00-uff]/;
            return !rech.test(str);
        }
        function numchange() {
            var strlen = 0; //初始定义长度为0
            var txtval = $.trim($onthis.val());
            for (var i = 0; i < txtval.length; i++) {
                if (ischinese(txtval.charat(i)) == true) {
                    strlen = strlen + 2; //中文为2个字符
                } else {
                    strlen = strlen + 1; //英文一个字符
                }
            }
            strlen = math.ceil(strlen / 2); //中英文相加除2取整数
            if ($num - strlen < 0) {
                $par.html("超出 <b style='color:red;font-weight:lighter' class=" + $numname + ">" + math.abs($num - strlen) + "</b> 字"); //超出的样式
            }
            else {
                $par.html("还可以输入 <b class=" + $numname + ">" + ($num - strlen) + "</b> 字"); //正常时候
            }
            $b.html($num - strlen);
        }
        $("." + $textareaname).live("focus", function () {
            $b = $(this).parents("." + $pname).find("." + $numname); //获取当前的数字
            $par = $b.parent();
            $onthis = $(this); //获取当前的textarea
            var setnum = setinterval(numchange, 500);
        });
    }
    textareafn();
</script>