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];
     };
 }