Javascript setdate getDate()+28 返回错误

Question

当我尝试向日期值添加天数时，我得到了奇怪的输出。

var startdate = $("#JobStartDate").val();

startdate = new Date(startdate);
startdate28 = startdate.setDate(startdate.getDate()+28);

console.log(startdate);
console.log(startdate28);

结果

startdate = "Date 2017-03-15T00:00:00.000Z"

startdate28 = 1489536000000

有什么想法我哪里出错了吗？

Answer 1

像这样:

var startdate = $("#JobStartDate").val();

startdate = new Date(startdate);
startdate28 = new Date();
startdate28.setDate(startdate.getDate()+28);

console.log(startdate);
console.log(startdate28);