js根据身份证获取出生年月日

function getBirthdatByIdNo(iIdNo) {
    var tmpStr = "";
    var idDate = "";
    var tmpInt = 0;
    var strReturn = "";

    iIdNo = iIdNo.replace(/^\s+|\s+$/g, "");

    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;
    }
}

调用方法能够返回出生日期： yyyy-MM-dd