JS 验证身份证号 根据身份证号获取出生日期

/*

js自身没有trim()函数取消字符串中的空白字符

自定义函数：用正则替换掉空白字符

*/

function trim(s) { return s.replace(/^\s+|\s+$/g, ""); };

//验证身份证号并获取出生日期
function getBirthdatByIdNo(iIdNo) {
var tmpStr = "";
var idDate = "";
var tmpInt = 0;
var strReturn = "";

iIdNo = trim(iIdNo);

if ((iIdNo.length != 15) && (iIdNo.length != 18)) {
strReturn = "输入的身份证号位数错误";
return strReturn;
}

if (iIdNo.length == 15) {
tmpStr = iIdNo.substring(6, 12);
tmpStr = "19" + tmpStr;
tmpStr = tmpStr.substring(0, 4) + "-" + tmpStr.substring(4, 6) + "-" + tmpStr.substring(6)

return tmpStr;
}
else {
tmpStr = iIdNo.substring(6, 14);
tmpStr = tmpStr.substring(0, 4) + "-" + tmpStr.substring(4, 6) + "-" + tmpStr.substring(6)

return tmpStr;
}
}