主要实现

• 1、针对18位、15位身份证号码进行校验
• 2、不区分xX大小写
• 3、把15位的身份证转换成18位的身份证，然后获取年龄

实现步骤

• 定义身份证省的编码

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"
    }; 

• 检查号码是否符合规范，包括长度，类型

function isCardNo(card){ 
 //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}$)|(^\d{17}(\d|X|x)$)/; 
 if(reg.test(card) === false){ 
 //alert("demo"); 
 return false; 
 } 
 return true; 
} 

• 取身份证前两位,校验省份

function checkProvince(card){ 
 var province = card.substr(0,2); 
 if(vcity[province] == undefined){ 
 return false; 
 } 
 return true; 
} 

• 检查生日是否正确

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

function verifyBirthday(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

function checkParity(card){ 
 //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.toUpperCase() == card.substr(17, 1).toUpperCase()) 
   { 
     return true; 
   } 
   return false; 
 } 
 return false; 
} 

• 15位转18位身份证号

function changeFivteenToEighteen(card){ 
 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; 
}

• 综合以上方法，判断

//idCard用户输入的身份证号
if(isCardNo(idCard) && checkProvince(idCard) && checkBirthday(idCard) && checkParity(idCard)){
  //如果以上判断全部合格
  if(idCard.length==15){
    //如果用户输入的身份证为15位，先转化为18位
    idCard= changeFivteenToEighteen(idCard);
  }
  var myDate = new Date();
  var year = myDate.getFullYear();
  var age=idCard-card.substring(6, 10)+'岁';//当前用户的年龄
}