获取n天后的日期

getDateAfter_n(days){

let date = new Date();

date.setDate(date.getDate() + days);

let yearStr = date.getFullYear();

let monthStr = ("0"+(date.getMonth()+1)).slice(-2, 8);

let dayStr = ("0"+date.getDate()).slice(-2, 8);

let result = "";

result = yearStr+'-'+monthStr+'-'+dayStr;

return result;

}