Modern JavaScript & TypeScript covers: ES6 & Beyond, Async & Performance, From ES5 to ESNext, Get Programming with JavaScript Next. Master ES6+ features (destructuring, arrow functions, template literals, generators, iterators, Proxy, Reflect), async patterns (promises, async/await, generators), and TypeScript fundamentals. Move from "I write ES5 JavaScript" to "I write modern TypeScript."
ES6 destructuring is like Ruby's multiple assignment on steroids: const { name, email } = user is like name, email = user.values_at(:name, :email) but cleaner. Arrow functions are like Ruby lambdas with implicit this binding. async/await is like what Concurrent::Future would be if Ruby had native syntax for it. TypeScript's type system is like Sorbet/RBS but more mature and better integrated into the toolchain. If you have used sig { params(name: String).returns(Boolean) } in Sorbet, TypeScript's function greet(name: string): boolean will feel familiar.
This course unlocks once you've finished its prerequisite. Open prerequisite →
TypeScript will feel like coming home. After years of Ruby's duck typing -- where you discover a method doesn't exist at runtime, in production, on a Friday -- TypeScript catches …
Somewhere in your Rails app there is a Stimulus controller you wrote by copying another Stimulus controller. It has const { target } = event, an arrow function or two, maybe a tem…
Here is a four-line program that separates JavaScript users from JavaScript engineers:
Open a PR from any active JavaScript codebase and you'll hit code like this:
Ruby gave you lazy enumerables and you probably use them without ceremony:
Work through each item before the checkpoint.
Every function is three lines of JavaScript and a real conversation with the type system. any is banned and CI enforces it; the strict tsconfig stays strict.
7 lessons. Read in order; spiral back when you need to. By the end you'll have used the core ideas twice — once on the abstract, once on something you'll meet at work next week.