What's the difference between saveUninitialized and resave?

I thought I would start off with a basic answer, my bit of understanding so far, and improve it together. Important question been 'dead' for too long.

From this I understand the difference is:

(Unmodified 'state' is different to uninitialized state)

resave: For any request made

• Nothing in the session needs to change (no login etc).
• Change of session required (logged in)

"Forces session to be saved even when unmodified"

saveUninitialized: Is about the state of the session, if its still in the uninitialized state.

• Not modified only, nothing in the session needs to change (no login etc).

"Forces a session that is "uninitialized" to be saved to the store. A session is uninitialized when it is new but not modified."

Basically, a session is saved in the store only when it is modified; if you add, delete or edit a session cookie (eg: req.session.test = 'some value'). If you want all the sessions to be saved in store, even if they don't have any modifications go with saveUninitialized: true.

Now, re-saving also happens only when session variables/cookies changes. If you want to save then always go ahead with resave: true