根据出生日期计算年龄

//出生年月日处理
var csny= stuInfo.csny;
var csnyArr=csny.split("-");
var birthYear = csnyArr[0];
var birthMonth = csnyArr[1];
var birthDay = csnyArr[2];

//当前年月日处理
var nowDate = new Date();
var nowYear = nowDate.getFullYear();
var nowMonth = nowDate.getMonth() + 1;
var nowDay = nowDate.getDate();

if(nowMonth>birthMonth){
    alert(nowYear-birthYear);
}else if((nowMonth-birthMonth==0)&&nowDay>=birthDay){
    alert(nowYear-birthYear);
}else{
    alert(nowYear-birthYear-1);