js获取指定日期n天之后的日期

function addDays(date, days,seperator='-') {
let oDate = new Date(date).valueOf();
let nDate = oDate + days * 24 * 3600 * 1000;
nDate = new Date(nDate);
let y = nDate.getFullYear().toString().padStart(2, 0);
let m = (nDate.getMonth() + 1).toString().padStart(2, 0);
let d = nDate.getDate().toString().padStart(2, 0);
return `${y}${seperator}${m}${seperator}${d}`
}