js 验证身份证号

function checkCardId(){ var socialNo = document.getElementById("idcard").value;if(socialNo == "")  {  alert("输入身份证号码不能为空!");  return (false);  }  if (socialNo.length != 15 && socialNo.length != 18)  {  alert("输入身份证号码格式不正确!");  return (false);  }  var area={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"};   if(area[parseInt(socialNo.substr(0,2))]==null) {  alert("身份证号码不正确(地区非法)!");  return (false);  }   if (socialNo.length == 15)  {  pattern= /^\d{15}$/;  if (pattern.exec(socialNo)==null){  alert("15位身份证号码必须为数字！");  return (false);  }  var birth = parseInt("19" + socialNo.substr(6,2));  var month = socialNo.substr(8,2);  var day = parseInt(socialNo.substr(10,2));  switch(month) {  case '01':  case '03':  case '05':  case '07':  case '08':  case '10':  case '12':  if(day>31) {  alert('输入身份证号码不格式正确!');  return false;  }  break;  case '04':  case '06':  case '09':  case '11':  if(day>30) {  alert('输入身份证号码不格式正确!');  return false;  }  break;  case '02':  if((birth % 4 == 0 && birth % 100 != 0) || birth % 400 == 0) {  if(day>29) {  alert('输入身份证号码不格式正确!');  return false;  }  } else {  if(day>28) {  alert('输入身份证号码不格式正确!');  return false;  }  }  break;  default:  alert('输入身份证号码不格式正确!');  return false;  }  var nowYear = new Date().getYear();  if(nowYear - parseInt(birth)<15 || nowYear - parseInt(birth)>100) {  alert('输入身份证号码不格式正确!');  return false;  }  return (true);  }  var Wi = new Array(  7,9,10,5,8,4,2,1,6,  3,7,9,10,5,8,4,2,1  ); var   lSum        = 0;  var   nNum        = 0;  var   nCheckSum   = 0;  for (i = 0; i < 17; ++i)  {  if ( socialNo.charAt(i) < '0' || socialNo.charAt(i) > '9' )  {  alert("输入身份证号码格式不正确!");  return (false);  }  else  {  nNum = socialNo.charAt(i) - '0';  }  var ss = Wi[i];lSum += nNum * Wi[i];  }if( socialNo.charAt(17) == 'X' || socialNo.charAt(17) == 'x')  {  lSum += 10*Wi[17];  }  else if ( socialNo.charAt(17) < '0' || socialNo.charAt(17) > '9' )  {  alert("输入身份证号码格式不正确!");  return (false);  }  else  {  lSum += ( socialNo.charAt(17) - '0' ) * Wi[17];  }  if ( (lSum % 11) == 1 )  {  alert("正确!");return true;  }  else  {  alert("身份证号码格式不正确!");  return (false);  }  }

<input type="text" id="idcard" size="30" />
&nbsp;&nbsp;
<input type="button" id="btn" οnclick="javascript:checkCardId();" />