/**
    * 字(zi)符串長度-中文和(he)全角(jiao)符號(hao)為2，英文、數字(zi)和(he)半角(jiao)為1
    * @param str
    * @return {Number}
    */
    var getLength = function (str) {
        return Math.ceil(str.replace(/^\s+|\s+$/ig, '').replace(/[^\x00-\xff]/ig, 'xx').length);
    };
    /**
    * 按字(zi)數截取(qu)字(zi)符串
    * @param str
    * @param len
    * @return {*}
    */
    var subStr = function (str, len) {
        if (!str) {
            return '';
        }
        len = len > 0 ? len * 2 : 280;
        var count = 0, //計(ji)數：中文2字節(jie)，英文1字節(jie)
            temp = '';  //臨時字符串
        for (var i = 0; i < str.length; i++) {
            if (str.charCodeAt(i) > 255) {
                count += 2;
            }
            else {
                count++;
            }
            //如果增(zeng)加計數(shu)后長度大(da)于限定長度，就直接返回臨時字符串
            if (count > len) {
                return temp;
            }
            //將當前內容加(jia)到臨時字符(fu)串
            temp += str.charAt(i);
        }
        return str;
    };
    var checkStrLength = function (str, minL, maxL) {
        var len = getLength($.trim(str));
        var data = {
            'checkL': (len >= minL && len <= maxL),
            'restL': maxL - len,
            'restStr': subStr(str, maxL)
        };
        return data;
    };

    /*擴展的字符長度(du)驗證,支持中文占兩個字符的空間*/
    kv.rules['extMinLength'] = {
        validator: function (val, minLength) {
            if (!kv.utils.isEmptyVal(val)) {
                console.log(getLength(val));
                console.log(minLength);
            }
            return kv.utils.isEmptyVal(val) || getLength(val) >= minLength;
        },
        message: 'Please enter at least {0} characters.(extension validator for zzl)'
    };

    kv.rules['extMaxLength'] = {
        validator: function (val, maxLength) {
            return kv.utils.isEmptyVal(val) || getLength(val) <= maxLength;
        },
        message: 'Please enter no more than {0} characters.(extension validator for zzl)'
    };

   self.extName = ko.observable().extend({
                extMinLength: 4,
                extMaxLength: { params: 20, message: "名字太長了" },
     });