Javascript校验身份证是不是合法

    validateIdCard: function (code) {
        var self = addBank;
        //身份证号合法性验证
        //支持15位和18位身份证号
        //支持地址编码、出生日期、校验位验证
        var city={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 "};
        var tip = "";
        var pass= true;

        if(!code || !/^\d{6}(18|19|20)?\d{2}(0[1-9]|1[012])(0[1-9]|[12]\d|3[01])\d{3}(\d|X)$/i.test(code)){
            tip = "身份证号格式错误";
            pass = false;
        }
        else if(!city[code.substr(0,2)]){
            tip = "地址编码错误";
            pass = false;
        }
        else{
            //18位身份证需要验证最后一位校验位
            if(code.length == 18){
                code = code.split('');
                //∑(ai×Wi)(mod 11)
                //加权因子
                var factor = [ 7, 9, 10, 5, 8, 4, 2, 1, 6, 3, 7, 9, 10, 5, 8, 4, 2 ];
                //校验位
                var parity = [ 1, 0, 'X', 9, 8, 7, 6, 5, 4, 3, 2 ];
                var sum = 0;
                var ai = 0;
                var wi = 0;
                for (var i = 0; i < 17; i++)
                {
                    ai = code[i];
                    wi = factor[i];
                    sum += ai * wi;
                }
                var last = parity[sum % 11];
                if(parity[sum % 11] != code[17]){
                    tip = "校验位错误";
                    pass =false;
                }
            }
        }
        if(!pass) {
            document.getElementsByClassName("identity-input-area-hint")[0].innerHTML = "请填写正确的身份证信息";
            document.getElementsByClassName("identity-input-area-hint")[0].style.display = "block";
            console.log(tip);
        } else {
            document.getElementsByClassName("identity-input-area-hint")[0].style.display = "none";
        }
        return pass;
    }