JS根据身份证号码 设置性别

   <script language="javascript">      
     var powers=new Array("7","9","10","5","8","4","2","1","6","3","7","9","10","5","8","4","2");    
       var parityBit=new Array("1","0","X","9","8","7","6","5","4","3","2");    
        var sex="male";    
        //校验身份证号码的主调用    
       
        function validId(obj){    
            var _id=obj.value;    
           if(_id=="")return;    
           var _valid=false;    
           if(_id.length==15){    
               _valid=validId15(_id);    
           }else if(_id.length==18){    
               _valid=validId18(_id);    
           }    
           if(!_valid){    
               alert("身份证号码有误,请检查!");    
               obj.focus();    
               return;    
           }
          
           //根据身份证号码  设置性别
           if(sex == "male"){
                document.getElementById("male").checked=true;
           }else{
                document.getElementById("female").checked=true;
           }
       
       }        
       //校验18位的身份证号码    
      
      function validId18(_id){    
           _id=_id+"";    
           var _num=_id.substr(0,17);    
           var _parityBit=_id.substr(17);    
           var _power=0;    
           for(var i=0;i< 17;i++){    
               //校验每一位的合法性    
      
               if(_num.charAt(i)<'0'||_num.charAt(i)>'9'){    
                   return false;    
                   break;    
               }else{    
                   //加权    
      
                   _power+=parseInt(_num.charAt(i))*parseInt(powers[i]);    
                   //设置性别    
      
                   if(i==16&&parseInt(_num.charAt(i))%2==0){    
                       sex="female";    
                   }else{    
                       sex="male";    
                   }    
               }    
           }    
          //取模    
      
           var mod=parseInt(_power)%11;    
          if(parityBit[mod]==_parityBit){    
              return true;    
          }    
           return false;    
       }    
      //校验15位的身份证号码    
      
       function validId15(_id){    
           _id=_id+"";    
           for(var i=0;i<_id.length;i++){    
               //校验每一位的合法性    
      
              if(_id.charAt(i)<'0'||_id.charAt(i)>'9'){    
                   return false;    
                   break;    
               }    
           }    
           var year=_id.substr(6,2);    
           var month=_id.substr(8,2);    
           var day=_id.substr(10,2);    
           var sexBit=_id.substr(14);    
           //校验年份位    
      
           if(year<'01'||year >'90')return false;    
          //校验月份    
      
           if(month<'01'||month >'12')return false;    
           //校验日    
      
           if(day<'01'||day >'31')return false;    
          //设置性别    
      
          if(sexBit%2==0){    
              sex="female";    
           }else{    
               sex="male";    
           }    
           return true;    
      }    
 </script>    
  <input type="text" onchange="validId(this)" maxlength=18 size=18>    
  <input type="radio" id="male" name="sex" checked value="male">男 <input type="radio" id="female" name="sex" value="female">女