What's the correct way to use maxAge with Express.js?

I have seen several variations. Suppose I wish my cookie to expire after one second. Should I use

app.use(express.session({ secret: 'mysecret',  maxAge: new Date(Date.now() + 1000)}));

or

app.use(express.session({ secret: 'mysecret',  maxAge: 1000}));

or

app.use(express.session({ secret: 'mysecret',  cookie: {maxAge: new Date(Date.now() + 1000)}}));

or

app.use(express.session({ secret: 'mysecret',  cookie: {maxAge: 1000}}));

Also suppose I have set my cookie expiring correctly and it has expired. If the user does not restart their browser do they still retain the cookie information until they do so?

I think you'll be better off looking at the source directly.

For Express it uses connect middleware, and here's the code for session https://github.com/senchalabs/connect/blob/master/lib/middleware/session.js#L67

And theres more documentation at the connect site http://www.senchalabs.org/connect/session.html

So you can do 

app.use(express.session({ secret: 'mysecret',  cookie: {expires: new Date(Date.now() + 1000)}}));

or

app.use(express.session({ secret: 'mysecret',  cookie: {maxAge: 1000}}));