jquery validate 身份证验证（可以为空）

jQuery.validator.addMethod('idCard2', function (value, element) {
    var vcity = {
        11: "北京", 12: "天津", 13: "河北", 14: "山西", 15: "内蒙古",
        21: "辽宁", 22: "吉林", 23: "黑龙江", 31: "上海", 32: "江苏",
        33: "浙江", 34: "安徽", 35: "福建", 36: "江西", 37: "山东", 41: "河南",
        42: "湖北", 43: "湖南", 44: "广东", 45: "广西", 46: "海南", 50: "重庆",
        51: "四川", 52: "贵州", 53: "云南", 54: "西藏", 61: "陕西", 62: "甘肃",
        63: "青海", 64: "宁夏", 65: "新疆", 71: "台湾", 81: "香港", 82: "澳门", 91: "国外"
    };

    // 判断是否为空
    isEmpty = function(card){
        if (/^\s*$/.test(card) === true) {
            return true;
        }
    }
    //检查号码是否符合规范，包括长度，类型  
    isCardNo = function (card) {
        if( isEmpty(card) ){
            return true;
        }
        //身份证号码为15位或者18位，15位时全为数字，18位前17位为数字，最后一位是校验位，可能为数字或字符X  
        var reg = /(^\d{15}$)|(^\d{17}(\d|X)$)/;
        if (reg.test(card) === false) {
            return false;
        }
        return true;
    };

    //取身份证前两位,校验省份  
    checkProvince = function (card) {
       if( isEmpty(card) ){
            return true;
        }
       var province = card.substr(0, 2);
       if (vcity[province] == undefined) {
        return false;
    }
    return true;
};

    //检查生日是否正确  
    checkBirthday = function (card) {
      if( isEmpty(card) ){
            return true;
        }
      var len = card.length;
        //身份证15位时，次序为省（3位）市（3位）年（2位）月（2位）日（2位）校验位（3位），皆为数字  
        if (len == '15') {
            var re_fifteen = /^(\d{6})(\d{2})(\d{2})(\d{2})(\d{3})$/;
            var arr_data = card.match(re_fifteen);
            var year = arr_data[2];
            var month = arr_data[3];
            var day = arr_data[4];
            var birthday = new Date('19' + year + '/' + month + '/' + day);
            return verifyBirthday('19' + year, month, day, birthday);
        }
        //身份证18位时，次序为省（3位）市（3位）年（4位）月（2位）日（2位）校验位（4位），校验位末尾可能为X  
        if (len == '18') {
            var re_eighteen = /^(\d{6})(\d{4})(\d{2})(\d{2})(\d{3})([0-9]|X)$/;
            var arr_data = card.match(re_eighteen);
            var year = arr_data[2];
            var month = arr_data[3];
            var day = arr_data[4];
            var birthday = new Date(year + '/' + month + '/' + day);
            return verifyBirthday(year, month, day, birthday);
        }
        return false;
    };

    //校验日期  
    verifyBirthday = function (year, month, day, birthday) {
        var now = new Date();
        var now_year = now.getFullYear();
        //年月日是否合理  
        if (birthday.getFullYear() == year && (birthday.getMonth() + 1) == month && birthday.getDate() == day) {
            //判断年份的范围（3岁到100岁之间)  
            var time = now_year - year;
            if (time >= 3 && time <= 100) {
                return true;
            }
            return false;
        }
        return false;
    };

    //校验位的检测  
    checkParity = function (card) {
      if( isEmpty(card) ){
            return true;
        }
        //15位转18位  
        card = changeFivteenToEighteen(card);
        var len = card.length;
        if (len == '18') {
            var arrInt = new Array(7, 9, 10, 5, 8, 4, 2, 1, 6, 3, 7, 9, 10, 5, 8, 4, 2);
            var arrCh = new Array('1', '0', 'X', '9', '8', '7', '6', '5', '4', '3', '2');
            var cardTemp = 0, i, valnum;
            for (i = 0; i < 17; i++) {
                cardTemp += card.substr(i, 1) * arrInt[i];
            }
            valnum = arrCh[cardTemp % 11];
            if (valnum == card.substr(17, 1)) {
                return true;
            }
            return false;
        }
        return false;
    };

    //15位转18位身份证号  
    changeFivteenToEighteen = function (card) {
      if( isEmpty(card) ){
            return true;
        }
      if (card.length == '15') {
        var arrInt = new Array(7, 9, 10, 5, 8, 4, 2, 1, 6, 3, 7, 9, 10, 5, 8, 4, 2);
        var arrCh = new Array('1', '0', 'X', '9', '8', '7', '6', '5', '4', '3', '2');
        var cardTemp = 0, i;
        card = card.substr(0, 6) + '19' + card.substr(6, card.length - 6);
        for (i = 0; i < 17; i++) {
            cardTemp += card.substr(i, 1) * arrInt[i];
        }
        card += arrCh[cardTemp % 11];
        return card;
    }
    return card;
};

    //checkCard = function () {
        var card = value;
    //校验长度，类型  
    if (isCardNo(card) === false) {
        //alert('您输入的身份证号码不正确，请重新输入');
        //document.getElementById('card_no').focus;
        return false;
    }
    //检查省份  
    if (checkProvince(card) === false) {
        return false;
    }
    //校验生日  
    if (checkBirthday(card) === false) {
        return false;
    }
    //检验位的检测  
    if (checkParity(card) === false) {
        return false;
    }

    return true;
});