关于 vue中对日期的大小处理的问题

有多个日期 可能是三个日期 也可能是五个日期
想要判断出 哪个日期是最后的日期 并且返回这个日期出来

 let daytime1 =['2021-7-8','2021-10-8','2021-10-9']
 let daytime2 =['2021-7-8','2021-10-8','2021-10-9','2021-11-9','2021-11-11']

let daytime1 =['2021-7-8','2021-10-8','2021-10-9']
//降序
daytime1.sort((a,b) => {
    return  new Date(b).getTime() -  new Date(a).getTime()
})
let maxDayTime = daytime1[0];

 let daytime1 =['2021-7-8','2021-10-8','2021-10-9']
 let daytime2 =['2021-7-8','2021-10-8','2021-10-9','2021-11-9','2021-11-11']
 Array.prototype.max = function () {
            return this.reduce((pre, cur) => {
                return new Date(pre) > new Date(cur) ? (pre) : cur
            })
        }
console.log(daytime1.max());
console.log(daytime2.max());

降序sort一下，取第一个呀

daytime2 =['2021-7-8','2021-10-8','2021-10-9','2021-11-9','2021-11-11']
sorted = daytime2.sort((a,b)=>{return new Date(b) - new Date(a)});
console.log(sorted[0]); //'2021-11-11' 这个就是结果了