js检查身份证号是否正确

转的，比较完善的验证身份证号的代码

/*
check(ID)验证身份证号码
返回值：0 : "是正确的身份证号"
        1 : "身份证校验不符合求和模11=1这个等式",
        2 : "身份证最后一位校验位有误",
        3 : "身份证位数不正确",
        4 : "年份错误",
        5 : "月份错误",
        6 : "日错误"
        
*/

function check(ID) {
    var ck = new IDCard();
    ck.check(ID);
    return ck.errNum;
}

function IDCard(ID) {
    var me = this;
    this.checkCode = new Array(1, 0, 'X', 9, 8, 7, 6, 5, 4, 3, 2);
    this.ID;
    this.errNum = 0;
    this.err = {
        1 : "身份证校验不符合求和模11=1这个等式",
        2 : "身份证最后一位校验位有误",
        3 : "身份证位数不正确",
        4 : "年份错误",
        5 : "月份错误",
        6 : "日错误"
    };
    this.err_msg = function() {
        return (0 !== this.errNum) ? this.err[this.errNum] : null;
    };
    this.check = function(ID) {
        this.errNum = 0;
        this.ID = ID;
        if (cardValidate()) {
            if (!aiCheck()) this.errNum = 1;
            if (!LastByteCheck()) this.errNum = 2;
            return (0 === this.errNum) ? true: false;
        } else {
            return false;
        }
    };
    function getNum(str) {
        var re = /^[0]*([0-9]*)$/;
        str.match(re);
        return parseInt(RegExp.$1,10);
    }
    //对身份证位数，出生日期，初步验证
    function cardValidate() {
        var re = /^[0-9x]{15,18}$/i;
        if (!re.test(me.ID)) {
            me.errNum = 7;
            return false;
        }
        if (15 == me.ID.length || 18 == me.ID.length) {
            var realLen = 0;
            if (18 == me.ID.length) realLen = 2;
            var year = parseInt(me.ID.substr(6, 2 + realLen),10);
            var month = getNum(me.ID.substr(8 + realLen, 2));
            var day = parseInt(me.ID.substr(10 + realLen, 2),10);
            if (4 == year.length) if (year < 1900 || year > 2050) me.errNum = 4;
            if (month < 1 || month > 12) me.errNum = 5;
            if (day < 1 || day > 31) me.errNum = 6;
            return 0 === me.errNum;
        } else {
            me.errNum = 3;
            return false;
        }
    }
    //总和模11应该等于1
    var aiCheck = function() {
        var sum = 0;
        for (var i = 1; i <= me.ID.length; i++) {
            var ai = me.ID.substr(me.ID.length - i, 1);
            ai = (ai.toLowerCase() == 'x') ? 10 : ai;
            var wi = Math.pow(2, i - 1) % 11;
            sum += parseInt(ai,10) * wi;
        }
        return 1 == sum % 11;
    };
    //最后一位校验，这个可以和aiCheck合在一起，减少一次循环
    var LastByteCheck = function() {
        var sum = 0;
        for (var i = 2; i <= me.ID.length; i++) {
            var ai = me.ID.substr(me.ID.length - i, 1);
            ai = (ai.toLowerCase() == 'x') ? 10 : ai;
            var wi = Math.pow(2, i - 1) % 11;
            sum += parseInt(ai,10) * wi;
        }
        var checkCodeIndex = sum % 11;
        var c = me.ID.substr(me.ID.length - 1, 1);
        //alert(c+"=="+me.checkCode[checkCodeIndex]);
        return c == me.checkCode[checkCodeIndex];
    };
}