如何在javascript中操作日期变量？

Question

我得到了以下变量：

today = new Date();
date = today.getFullYear()+'-'+(today.getMonth()+1)+'-'+today.getDate();

console.log(date)

------
Output
------
2021-9-6

我怎样才能得到昨天或两天前的日期？我试过：

console.log(today-2)
console.log(date-2)
------
Output
------
1630936602270
NaN

我期待着折叠输出2021-9-4

Answer 1

let twoDaysAgoInMs =2*24*3600*1000;
console.log(new Date((new Date()).getTime()- twoDaysAgoInMs))


 // to get only YYYY-mm-dd
 console.log(new Date((new Date()).getTime()- twoDaysAgoInMs).toISOString().substring(0,10))