//格式化时间
                formateTime(t){
                    if(t instanceof Date){
                        let year = t.getFullYear();
                        let month = t.getMonth()+1;
                        month =  month < 10 ? "0"+month : month;
                        let day = t.getDate();
                        day =  day < day : day;
                        console.log(year,month,day);
                        res=year+""+month+""+day;
                        return res; 
                    }
                    return "";
                }