从盛大通行证上摘下来的身份证验证代码

<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>