Course · 9 lessons ~48 hr Intermediate

JavaScript Foundations — The Language Itself

JavaScript Foundations — The Language Itself covers: Eloquent JavaScript, Up & Going, Scope & Closures, this & Object Prototypes, Types & Grammar. Deeply understand JavaScript as a programming language — not jQuery tricks, not framework syntax, but the language mechanics: closures, scope, prototypes, the event loop, coercion, this, and the module system. This is the foundation everything else builds on. You already understand blocks and procs — closures are the JavaScript equivalent. A Ruby block captures variables from its enclosing scope; a JavaScript closure does the same thing but is far more pervasive (every function is a closure). Ruby's self changes based on context; JavaScript's this does too, but with four different binding rules instead of Ruby's simpler model. Ruby's require is like JavaScript's import, but JS went through three module systems (CommonJS, AMD, ES Modules) before settling on one. Understanding this history explains why Node.js uses require() while browsers use import.

reading · we frame, you read MIT or the canonical taught · we author, no canonical fits ↺ spirals back to earlier lessons

reflection reading · 8 min

Honest Take — Before You Begin

Here is the honest truth: JavaScript will offend your Ruby sensibilities. Ruby was designed to make programmers happy. JavaScript was designed in ten days to make Netscape ship. Y…

preview →

reading · 30 min + ~320 min canonical L1

Eloquent JavaScript: The Introduction That Respects Your Intelligence

You have already written JavaScript. A Stimulus controller here, a fetch call there, an event listener copied from a blog post and adjusted until it worked. That is exactly the re…

primary MDN JavaScript Guide

after L1 locked

reading · 30 min + ~320 min canonical L1

Up & Going: The Case That You Don't Know JS Yet

There is a specific kind of confidence that comes from shipping production features in a language for years. And there is a specific kind of humility that comes from a page of tha…

primary MDN JavaScript Guide

after L2 locked

reading · 30 min + ~320 min canonical L1

Scope & Closures: The Volume That Makes Closures Click Forever

Here is a bug that has shipped to production from thousands of codebases:

primary MDN JavaScript Guide

after L3 locked

reading · 30 min + ~320 min canonical L1

this & Object Prototypes: Four Binding Rules and a Language Without Classes

In Ruby, self is well-behaved. You look at where code is written — class body, instance method, module — and you know what self is. It's a lexical question with a lexical answer.

primary MDN JavaScript Guide

after L4 locked

reading · 30 min + ~320 min canonical L1

Types & Grammar: Coercion Without Superstition

Every language community has its self-deprecating party trick. JavaScript's is famous:

primary MDN JavaScript Guide

after L5 locked

reading · 30 min + ~320 min canonical L1

The Good Parts: Crockford as History, Taste, and Counterargument

In 2008, JavaScript was a punchline. It was the language of popup blockers and copy-pasted form validators — nobody's idea of serious engineering. Then a Yahoo architect published…

primary MDN JavaScript Guide

after L6 locked

exercise reading · 30 min L1

Module Checklist

Work through each item before the checkpoint.

after L7 locked

project reading · 60 min L1

Project: Build a Module System

Pure JavaScript, no frameworks, no bundlers, no class. Closures, prototypes, and promises — the primitives every framework is made of. A constraint test statically rejects class a…

after L8 locked

9 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.