验证×××的有效性：

function checkIdcard(value){ var idcard = value; if(idcard==""){  return true; } var regex1 = /^[1-9][0-7]\d{4}((([0-9]{3}[1-9]|[0-9]{2}[1-9][0-9]{1}|[0-9]{1}[1-9][0-9]{2}|[1-9][0-9]{3})(((0[13578]|1[02])(0[1-9]|[12][0-9]|3[01]))|((0[469]|11)(0[1-9]|[12][0-9]|30))|(02(0[1-9]|[1][0-9]|2[0-8]))))|((([0-9]{2})(0[48]|[2468][048]|[13579][26])|((0[48]|[2468][048]|[3579][26])00))0229))\d{3}(\d|X|x)?$/; /*身份号码位数及格式检验*/ switch (idcard.length) {   case 15:  if ( (parseInt(idcard.substr(6,2))+1900) % 4 == 0 || ((parseInt(idcard.substr(6,2))+1900) % 100 == 0 && (parseInt(idcard.substr(6,2))+1900) % 4 == 0 )){   var regex2 = /^[1-9][0-9]{5}[0-9]{2}((01|03|05|07|08|10|12)(0[1-9]|[1-2][0-9]|3[0-1])|(04|06|09|11)(0[1-9]|[1-2][0-9]|30)|02(0[1-9]|[1-2][0-9]))[0-9]{3}$/;//测试出生日期的合法性  } else {   var regex2 = /^[1-9][0-9]{5}[0-9]{2}((01|03|05|07|08|10|12)(0[1-9]|[1-2][0-9]|3[0-1])|(04|06|09|11)(0[1-9]|[1-2][0-9]|30)|02(0[1-9]|1[0-9]|2[0-8]))[0-9]{3}$/;//测试出生日期的合法性  }  if(regex2.test(idcard))   return true;  else   return false;  break;   case 18:    if(regex1.test(idcard)){   var S = (parseInt(idcard.charAt(0)) + parseInt(idcard.charAt(10))) * 7 +                (parseInt(idcard.charAt(1)) + parseInt(idcard.charAt(11))) * 9 +                (parseInt(idcard.charAt(2)) + parseInt(idcard.charAt(12))) * 10 +                (parseInt(idcard.charAt(3)) + parseInt(idcard.charAt(13))) * 5 +                (parseInt(idcard.charAt(4)) + parseInt(idcard.charAt(14))) * 8 +                (parseInt(idcard.charAt(5)) + parseInt(idcard.charAt(15))) * 4 +                (parseInt(idcard.charAt(6)) + parseInt(idcard.charAt(16))) * 2 +                parseInt(idcard.charAt(7)) * 1 +                parseInt(idcard.charAt(8)) * 6 +                parseInt(idcard.charAt(9)) * 3;            var Y = S % 11;   var M = "F";   var JYM = "10X98765432";   M = JYM.substr(Y, 1);   /*判断校验位*/   if (M == idcard.charAt(17).toUpperCase()) {         //alert(Errors[0]+"18");    return true;   } else {    //alert(Errors[3]);    //showErrMsg = Errors[3];    return false;   }  }else{   return false;  }  break;   default:    //alert(Errors[1]);  //showErrMsg = Errors[1];  return false; }}