从盛大通行证上摘下来的身份证验证js代码

<script language="javascript" type="text/javascript"> 
function CheckIdCardField(v_card) { 
var reg = /^\d{15}(\d{2}[0-9X])?$/i; 
if (!reg.test(v_card)) { 
return false; 
} 
if (v_card.length == 15) { 
var n = new Date(); 
var y = n.getFullYear(); 
if (parseInt("19" + v_card.substr(6, 2)) < 1900 || parseInt("19" + v_card.substr(6, 2)) > y) { 
return false; 
} 
var birth = "19" + v_card.substr(6, 2) + "-" + v_card.substr(8, 2) + "-" + v_card.substr(10, 2); 
if (!isDate(birth)) { 
return false; 
} 
} 
if (v_card.length == 18) { 
var n = new Date(); 
var y = n.getFullYear(); 
if (parseInt(v_card.substr(6, 4)) < 1900 || parseInt(v_card.substr(6, 4)) > y) { 
return false; 
} 
var birth = v_card.substr(6, 4) + "-" + v_card.substr(10, 2) + "-" + v_card.substr(12, 2); 
if (!isDate(birth)) { 
return false; 
} 
iW = new Array(7, 9, 10, 5, 8, 4, 2, 1, 6, 3, 7, 9, 10, 5, 8, 4, 2, 1); 
iSum = 0; 
for (i = 0; i < 17; i++) { 
iC = v_card.charAt(i); 
iVal = parseInt(iC); 
iSum += iVal * iW[i]; 
} 
iJYM = iSum % 11; 
if (iJYM == 0) sJYM = "1"; 
else if (iJYM == 1) sJYM = "0"; 
else if (iJYM == 2) sJYM = "x"; 
else if (iJYM == 3) sJYM = "9"; 
else if (iJYM == 4) sJYM = "8"; 
else if (iJYM == 5) sJYM = "7"; 
else if (iJYM == 6) sJYM = "6"; 
else if (iJYM == 7) sJYM = "5"; 
else if (iJYM == 8) sJYM = "4"; 
else if (iJYM == 9) sJYM = "3"; 
else if (iJYM == 10) sJYM = "2"; 
var cCheck = v_card.charAt(17).toLowerCase(); 
if (cCheck != sJYM) { 
return false; 
} 
} 
return true; 
} 
</script>