Interview-grade practice for frontend developers
You know the answer.
Can you survive the follow-up?
Recognising a concept and being able to defend it under questioning are different skills. Praxis drills the second one — with reasoning-first quizzes, a map of where every idea comes from, an interviewer that cross-questions you, and spaced repetition so nothing slips.
Mock interview · Closures
The loop
Theory in plain language
The idea explained the way you'd explain it to a colleague — then shown inside real code.
Quizzes that explain why
Every option carries its reasoning. Being wrong teaches you something specific.
Concept genealogy
useState → closures → lexical environment → scope. Trace it once and the API stops being memorisation.
Mock interviews that probe
Answer shallowly and it digs, the way a senior interviewer finds the floor of what you know.
Spaced repetition
Whatever you fumble comes back right before you'd forget it. Weak spots surface on your dashboard.
Tracks
See all tracks →JavaScript Logic
30 lessonsThe reasoning foundations — scope, closures, and thinking in small repeatable steps.
React
30 lessonsHooks, rendering, and state — each traced back to the JavaScript idea underneath it.
Frontend Practices
30 lessonsThe practical, tooling, and systems knowledge interviews test beyond pure language syntax — APIs, architecture, workers, and the infrastructure around the code.
TypeScript
30 lessonsThe type system as a reasoning tool, not a chore — generics, narrowing, inference, and where it echoes ideas JavaScript already had.
UX Fundamentals
30 lessonsThe reasoning behind colour, type, and spacing — the frontend interview questions nobody drills.
Docker
30 lessonsImages, layers, and containers — what's actually happening when you run a build.
AWS
30 lessonsThe handful of services a frontend developer is actually expected to reason about.
Next.js
31 lessonsThe App Router, Server Components, and streaming — the parts that don't map cleanly onto plain React anymore.
AI Fundamentals
30 lessonsTokens, embeddings, context windows, RAG — the vocabulary, and the sane path to actually building with AI instead of just prompting it.
Modern CSS
30 lessonsContainer queries, :has(), subgrid, scroll-driven animations — what shipped recently, what's still shaky, and the @supports fallback for each.
Web Performance & Vitals
30 lessonsLCP, INP, CLS, and the budget mindset behind them — diagnosing why a page feels slow, not just measuring that it is.
Accessibility & ADA Compliance
30 lessonsSemantic HTML, ARIA, keyboard flows, and the legal side of ADA/WCAG — built as a discipline, not a lint-rule afterthought.
System Design for Frontend
30 lessonsThe shortest honest path through system design interviews — scale, caching, and trade-offs, sized for a frontend-focused round.
Frontend ↔ Backend Data Layer
30 lessonsHow API shape, caching, and fetching strategy become actual UI decisions — consuming a data layer, not just calling fetch.