Developer Foundations
Build demonstrated skill on a fixed competency standard; lesson realizations and assessment instances can vary by run.
Outcome: You can retain state, keep fee rules in one function, explain stale inventory after writes, and pass isomorphic prove probes where builders exist — without fake mastery claims.
2h 5m · 3 of 3 lessons · AI Coach included · Certificate available
Your progression
Evidence first
Where I started
Where I started
- No diagnostic snapshot yet — starting from the course baseline.
- Outcome target: You can retain state, keep fee rules in one function, explain stale inventory after writes, and pass isomorphic prove probes where builders exist — without fake mastery claims.
- First learning goal: build-website-app
Where I am now
Where I am now
- Still building evidence — completion % is secondary.
- No active practice lesson yet.
- Start the course to create a teaching run (anti-memorization variants).
Where I am going
Where I am going
- Next competency gap: Data & state retention (variables-state-retention)
- Certificate path: L1 completion available when the path finishes (not skill-verified L2).
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Sign in to start courseCreate accountLessons
- Preview
1. Data & state (checkout tip bug)
Explain why tip must be retained for checkout total, and prove it on a fresh isomorphic scenario.
Beginner40 minInteractive - Preview
2. Functions as single source (fee copy-paste)
Spot diverging copy-pasted fee logic, explain the risk, and prove a single-function fix on a fresh variant.
Beginner40 minInteractive - Preview
3. Objects & APIs (stale inventory)
Explain why inventory can stay stale after purchase and how shared product shape + freshness fixes it.
Beginner45 minInteractive