[JavaScript]YYYY-MM-DD格式字符串計算年齡

function getAge(birth){
    birth = birth.replace(/-/g,"/"); //把格式中的"-"替換爲"/"
    birth = new Date(birth ); //替換後轉爲Date類型
    var now = new Date(); //獲取當前日期
    var nowYear=now.getFullYear(); //當前日期的年份
    var nowMonth=now.getMonth();
    var nowDay=now.getDay();

    var birthYear=birth.getFullYear();
    var birthMonth=birth.getMonth();
    var birthDay=birth.getDay(); //出生日期的日數
    var age;
    
    if(birth>now){
        return false;
    }
    else if(nowYear==birthYear||(nowYear>birthYear&&nowMonth>=birthMonth&&nowDay>=birthDay)){
        age=nowYear-birthYear;
        }else {
            age=nowYear-birthYear-1; //簡而言之，沒過生日歲數不能+1
        }
    return age;
    }

另一種實現方式比較簡單：

function getAge(tmpStr){
        var nowdate = new Date();//今天
        var birth = new Date(tmpStr.replace(/-/g,"/"));//默認格式出生日期
        var age = ((nowdate-tmpStr)/1000/60/60/24/365);//計算年齡;
        return age;
}