5 weeks · 31 challenges Free preview · Pro path
Rebuild React from Scratch Reimplement the hooks, the context stack and the reconciler — in plain JavaScript.
Weekly roadmap
01 Hook Mechanics PRO02 Equality & Memoization PRO03 Composition & Component Patterns PRO04 Effects, Async & Batching PRO05 Reconciliation & Concurrent Rendering PROStarts with: useToggle Hook Start path
4 weeks · 24 challenges Week 1 free
JavaScript MasteryThe 24 patterns every senior JS dev should solve in their sleep.
Weekly roadmap
01 Arrays & Objects 6 02 Functions & Composition PRO03 Async Patterns PRO04 Data Structures PROStarts with: Flatten Array Start path
4 weeks · 24 challenges Free preview · Pro path
JavaScript Backend PathHTTP, rate limits, resilience — write code that survives prod traffic.
Weekly roadmap
01 Parsing & URLs PRO02 HTTP & Headers PRO03 Resilience PRO04 Advanced Backend PROStarts with: Parse Query String Start path
2 weeks · 12 challenges Free preview · Pro path
JS Advanced Patterns Design patterns, type-safe JS and functional techniques for senior engineers.
Weekly roadmap
01 Design Patterns PRO02 Type-Safe & Functional JS PROStarts with: Observer Pattern Start path
4 weeks · 18 challenges Free preview · Pro path
Clean Code & Refactoring Write code humans can read — not just machines.
Weekly roadmap
01 Functions PRO02 Principles PRO03 Advanced Patterns PRO04 SOLID & Classes PROStarts with: Extract Function Start path
2 weeks · 13 challenges Free preview · Pro path
JavaScript Server-Side SecuritySpot and fix the vulnerabilities that get JavaScript backends pwned in production.
Weekly roadmap
01 Injection & Input Validation PRO02 Access Control & Advanced Attacks PROStarts with: Parameterize SQL Query Start path
2 weeks · 12 challenges Free preview · Pro path
JavaScript Security PathGeneral and client-side JavaScript vulnerabilities the server-side path doesn't cover.
Weekly roadmap
01 Access Control, XSS & Data Exposure PRO02 Authentication, Cryptography & Advanced Attacks PROStarts with: Mass Assignment — Never Trust a Client-Supplied Role Start path
3 weeks · 9 challenges Free preview · Pro path
Functional Programming in JS Master compose, curry, monads and transducers — the patterns behind every great FP codebase.
Weekly roadmap
01 Core Combinators PRO02 Containers & Caching PRO03 Advanced Patterns PROStarts with: Compose Start path