js代码

<script type="text/javascript">
    //显示限制输入字符method
    function textAreaChange(obj){
        var $this = $(obj);
        var count_total = $this.next().children('span').text();
        var count_input = $this.next().children('em');
        var area_val = $this.val();
        if(area_val.len()>count_total){
            area_val = autoAddEllipsis(area_val,count_total);//根据字节截图内容
            $this.val(area_val);
            count_input.text(0);//显示可输入数
        }else{
            count_input.text(count_total - area_val.len());//显示可输入数
        }
    }
    //得到字符串的字节长度
    String.prototype.len = function(){
        return this.replace(/[^\x00-\xff]/g, "xx").length;
    };
    /*
     * 处理过长的字符串，截取并添加省略号
     * 注：半角长度为1，全角长度为2
     * pStr:字符串
     * pLen:截取长度
     * return: 截取后的字符串
     */
    function autoAddEllipsis(pStr, pLen) {
        var _ret = cutString(pStr, pLen);
        var _cutFlag = _ret.cutflag;
        var _cutStringn = _ret.cutstring;
        return _cutStringn;
    }
    /*
     * 取得指定长度的字符串
     * 注：半角长度为1，全角长度为2
     * pStr:字符串
     * pLen:截取长度
     * return: 截取后的字符串
     */
    function cutString(pStr, pLen) {
        // 原字符串长度
        var _strLen = pStr.length;
        var _tmpCode;
        var _cutString;
        // 默认情况下，返回的字符串是原字符串的一部分
        var _cutFlag = "1";
        var _lenCount = 0;
        var _ret = false;
        if (_strLen <= pLen/2){_cutString = pStr;_ret = true;}
        if (!_ret){
            for (var i = 0; i < _strLen ; i++ ){
                if (isFull(pStr.charAt(i))){_lenCount += 2;}
                else {_lenCount += 1;}
                if (_lenCount > pLen){_cutString = pStr.substring(0, i);_ret = true;break;}
                else if(_lenCount == pLen){_cutString = pStr.substring(0, i + 1);_ret = true;break;}
            }
        }
        if (!_ret){_cutString = pStr;_ret = true;}
        if (_cutString.length == _strLen){_cutFlag = "0";}
        return {"cutstring":_cutString, "cutflag":_cutFlag};
    }
    /*
     * 判断是否为全角
     *
     * pChar:长度为1的字符串
     * return: true:全角
     *         false:半角
     */
    function isFull (pChar){
        if((pChar.charCodeAt(0) > 128)){return true;}
        else{return false;}
    }
</script>