js时间戳和日期格式相互转换

// 时间戳转换时间 代码长，冗余    function getTime(nS) {      let date = new Date(nS);      let Y = date.getFullYear() + '-';      let M = (date.getMonth()+1 < 10 ? '0'+(date.getMonth()+1) : date.getMonth()+1) + '-';      let D = date.getDate() + ' ';      let h = date.getHours() + ':';      let m = date.getMinutes() + ':';      let s = date.getSeconds();      return Y+M+D+h+m+s;    }    let starTime = getTime(this.starTime);    let endTime = getTime(this.endTime);