JavaScript獲取指定的某一天的時間

 getDay(day){
    var today = new Date();
    var targetday=today.getTime() + 1000*60*60*24*day;
    today.setTime(targetday);  //關鍵代碼
    var tYear = today.getFullYear();  //獲取年份
    var tMonth = today.getMonth();  //獲取月份
    var tDate = today.getDate();  //獲取日期
    tMonth = this.doHandleMonth(tMonth + 1);  //獲取到的月份爲0-11
    tDate = this.doHandleMonth(tDate);  
    return tYear+"-"+tMonth+"-"+tDate;
},
doHandleMonth(month){  //判斷是否爲1-9,如果是,前面加0
    var m = month;
    if(month.toString().length == 1){
     m = "0" + month;
    }
    return m;
},