Bonus round. Parts 1–3 covered why Node exists, what's happening inside it, and the full request journey. This part mops up the pieces that didn't fit anywhere else — the Express plumbing, error handling, and a checklist to test yourself against.
Saturday, Round 4
Nephew: Uncle, one more round? I promise this is the last one for a while.
Uncle: pours chai — you said that last time too. Fine, what's bugging you now?
Nephew: Small things, actually. express.json(), cookie-parser, express.Router() — I use all of them, copy-pasted from old projects, but I couldn't explain any of them if you asked me directly.
