I’m just starting to learn jsdoc, so this is all new to me.

In exrpress-session we have a session object, which stores session data req.session. I’d like to store a userId in the session object. But when doing req.session.userId my IDE yells at me because userId does not exist on Session & Partial<SessionData> (which of course it does not, because I have never defined it anywhere).

1. As far as I understand Partial makes all attributes optional. I may not want this. Is it possible to ‘unpartial’ something?
2. How can I define the SessionData object with the userId?
3. What does Type1 & Type2 do exactly? I assume it combines the two types somehow?

Note: I’m only using js, so only jsdoc. No .ts or .d.ts files for me.

Edit:

I want to define my custom SessionData so that jsdoc doesn’t give me red error squiggles.

app.get('/something', (req, res, next) => {
    let uid = req.session.userId;
});

how can I tell jsdoc that .userId is part of my custom session object?