datetimeFormat() {
function paddingZero(number) {
const length = String(number).length;
return length === 1 ? '0'+number : number;
}
this.timer = setInterval(() => {
let month = paddingZero((new Date()).getMonth() + 1);
let day = paddingZero((new Date()).getDate());
let hours = paddingZero((new Date()).getHours());
let minutes = paddingZero((new Date()).getMinutes());
let seconds = paddingZero((new Date()).getSeconds());
this.datetime = `${(new Date()).getFullYear()}/${month}/${day} ${hours}:${minutes}:${seconds}`;
}, 1000);
},