From npx create-react-app
to production-ready. Tonight.
Every concept taught inside a live editor that runs real JSX. No videos. No slides. Just code that works — and you understanding why.
You've seen these. We'll fix them.
Every error below is a concept waiting to click. Flip each card to see the fix — then run it live in the sandbox. No more Stack Overflow roulette.
State initializes before your data arrives
Effects run after render. If they update state, React re-renders. If that triggers the effect again…
Without keys, React can't track which item changed — it may reuse the wrong component instance and corrupt your state
The full arc, concept by concept.
First 3 modules completely free. No account required to start.
JSX & The Component Model
Build your first component from scratch. Understand why JSX isn't HTML, and how React turns function calls into a UI tree.
useState & Async Updates
State doesn't update immediately. Learn why, and how to write components that don't crash when data hasn't arrived yet.
Lists + The Key Prop
Why React cares about keys. Stable IDs vs index keys. The state-corruption bug you don't know you have.
useEffect — What It Actually Is
Not componentDidMount. Not "run code on change." useEffect synchronizes your component with external systems.
The Dependency Array
The array that controls when effects re-run. Stale closures. The linter as your pair programmer.
Async in Effects
Why you can't `async` a useEffect directly. The inner-function pattern every senior dev knows.
Cleanup & Memory Leaks
Clear timers. Abort fetch requests. Unsubscribe from sockets. Your app shouldn't leak like a bucket.
When NOT to useEffect
Derived state belongs in render, not effects. Event handlers, not effects, for user actions. The rule that halves your bugs.
useCallback & useMemo
Stabilize your dependencies. Cache expensive calculations. Stop re-creating functions on every render.
Custom Hooks
Extract logic into reusable hooks. useFetch, useLocalStorage, useDebounce — build your toolkit.
Context & Global State
Prop drilling is a symptom. Context is the cure. When to reach for Zustand instead.
Ship Your First App
Assemble everything into a production-ready mini-app. Deploy to Vercel. Show it to someone.
Modules 1–3 · Full sandbox access · No credit card
Run real JSX. Understand state. Master the key prop. In under 90 minutes.
Run code first. Pay later. Maybe.
The teaching method proves itself before you commit to anything.
Free
- ✓Modules 1–3 with full sandbox access
- ✓JSX & component model
- ✓useState & async state
- ✓Lists + the key prop
- ✓Community Discord access
- ✓Progress saved to account
Pro
- ✓Everything in Free
- ✓Modules 4–12 with sandboxes
- ✓useEffect deep dive (4 modules)
- ✓Custom hooks & patterns
- ✓Context & global state
- ✓Ship your first app (Module 12)
- ✓Certificate of completion
- ✓Lifetime access + future updates
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Three developers. One breakthrough.
Bootcamp grads, career-switchers, and self-taught builders — they all got unstuck.
I had copied `useEffect` from Stack Overflow 40 times without ever understanding the dependency array. Module 4 fixed that in 20 minutes. The sandbox made it impossible not to understand.
As a Rails dev I kept thinking of React like MVC — controller, model, view. The mental model translation in Module 4 was the unlock. "Effects sync with external systems" finally made lifecycle methods make sense.
I had a working app but it was a disaster — keys were indices everywhere, effects running on every render. This course didn't just teach me the fix, it showed me why my "working" code was a time bomb.