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Closures & Scope, Finally
The mental model that makes JavaScript’s strangest behavior obvious — built through 31 progressive exercises.
Deep-Dive Workshops
One topic. All the way down.
Workshops are for the topics that deserve more than a chapter. Each one is self-paced and single-subject: short videos, dozens of progressive exercises, and a recorded solution walkthrough for every single one. Take them in any order, whenever a topic starts costing you sleep.
Six workshops, ordered by how often they save careers.
⟳
The Event Loop, Visualized
Tasks, microtasks, and rendering — see exactly why your async code runs in the order it does.
⌘
Type-Safe APIs End to End
Share types between client and server and let the compiler catch integration bugs before runtime.
✓
Testing Node Services in Practice
Unit, integration, and contract tests for real APIs — including the awkward parts: databases, time, and flaky networks.
⌗
Debugging with DevTools, Properly
Breakpoints, watch expressions, the Network and Performance panels — stop console.log archaeology forever.
◷
Performance Budgets & Core Web Vitals
The median page now ships over half a megabyte of JavaScript. Learn to measure, budget, and stay under it.
Watch a little. Build a lot. Compare notes.
1
Short, focused video
Lessons run five to twelve minutes and exist only to set up the next exercise. There are no hour-long lectures anywhere in the catalog.
2
Progressive exercises
Every concept is drilled through exercises that get harder one notch at a time — the same retrieval-practice structure as the main curriculum.
3
Solution walkthroughs
Every exercise ends with a recorded walkthrough of a reference solution — including the wrong turns, so you learn to recognize them.
Inside the featured three: full syllabi, nothing held back.
Workshop6h 40m · 31 exercises · Advanced
Closures & Scope, Finally
Closures are not a trick question — they’re the language’s memory model. This workshop builds the mental picture (environments, not “functions remembering things”) and then stress-tests it until loop-variable bugs, module patterns, and stale-state issues become obvious at a glance.
1Lexical scope, drawn as environments6 ex.
2Closures over loops & the classic bugs7 ex.
3Modules, factories & private state6 ex.
4Closures in async code & stale state7 ex.
5Memory, leaks & when closures cost you5 ex.
Further reading: MDN — Closures · You Don’t Know JS Yet: Scope & Closures (Kyle Simpson) · javascript.info — Variable scope, closure
Workshop4h 15m · 24 exercises · Intermediate
The Event Loop, Visualized
Built around an interactive visualizer: you write a snippet, predict the log order, then watch the task queue, microtask queue, and render steps play out frame by frame. By the end, “why did this run first?” stops being a mystery and starts being a boring, answerable question.
1The call stack & run-to-completion4 ex.
2Tasks: timers, events & I/O5 ex.
3Microtasks: promises & queueMicrotask6 ex.
4Rendering, rAF & jank5 ex.
5Node’s loop vs the browser’s4 ex.
Further reading & viewing: In the Loop (Jake Archibald, JSConf.Asia 2018) · What the heck is the event loop anyway? (Philip Roberts, JSConf EU 2014) · WHATWG HTML — Event loops · MDN — Execution model
Workshop8h 05m · 29 exercises · Advanced
Type-Safe APIs End to End
You build one product twice: first with hand-written fetch calls and hope, then with shared types and runtime validation at the boundary. The diff between the two — every integration bug the compiler now catches — is the entire argument for TypeScript across the stack.
1Where integration bugs come from4 ex.
2Sharing types between client & server6 ex.
3Runtime validation with schemas7 ex.
4Generics for API clients6 ex.
5Versioning & evolving contracts safely6 ex.
Further reading: The TypeScript Handbook (Microsoft) · Zod — schema validation docs · OpenAPI Specification
Workshop hours are total watch-plus-build time measured from cohort medians, and exercise counts are current as of this page’s last update. Every workshop is included with enrollment — there is no separate workshop fee.