// 获取近几天的时间
    getLatelyDay(day) {
        var today = new Date();
        var targetday_milliseconds=today.getTime() + 1000*60*60*24*day;
        today.setTime(targetday_milliseconds); //注意，这行是关键代码
        var tYear = today.getFullYear();
        var tMonth = today.getMonth();
        var tDate = today.getDate();
        tMonth = this.doHandleMonth(tMonth + 1);
        tDate = this.doHandleMonth(tDate);
        return tYear+"-"+tMonth+"-"+tDate;
    }
doHandleMonth(month){
        var m = month;
        if(month.toString().length == 1){
         m = "0" + month;
        }
        return m;
    }