详解正则表达式实现二代身份证号码验证

IdCodeValid:function(code){
 //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 row={
 'pass':true,
 'msg':'验证成功'
 };
 if(!code || !/^\d{6}(18|19|20)?\d{2}(0[1-9]|1[012])(0[1-9]|[12]\d|3[01])\d{3}(\d|[xX])$/.test(code)){
 row={
  'pass':false,
  'msg':'身份证号格式错误'
 };
 }else if(!city[code.substr(0,2)]){
 row={
  'pass':false,
  'msg':'身份证号地址编码错误'
 };
 }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;
  }
  if(parity[sum % 11] != code[17].toUpperCase()){
  row={
   'pass':false,
   'msg':'身份证号校验位错误'
  };
  }
 }
 }
 return row;
}
IdCodeValid('xxx');