cookie默认的生命周期，是跟着session走的。session结束了，cookie也就被自动清除了。不过可以设置cookie的过期时间来避免自动清除
Cookies are deleted when I close the browser?
The default cookie lifetime is “session”. You should set a maxAge:
this.cookies.set(Auth.STORAGE_KEY, token,
{ path: '/', maxAge: 31536000 });
It’s in seconds.
365*24*3600=31536000一年的秒数
what is the default expiration time of a cookie
The default Expires value for a cookie is not a static time, but it creates a Session cookie. This will stay active until the user closes their browser/clears their cookies. You can override this as required.
From the linked page:
Setting the Expires property to MinValue makes this a session Cookie, which is its default value