22 concepts, indexed

foundational · js

The language of the web. Dynamic, prototype-based, single-threaded with an event loop.

foundational · js/variables

Named references to values. `let` for mutables, `const` for one-time bindings; `var` exists for legacy code.

foundational · js/primitive-types

string, number, boolean, null, undefined, symbol, bigint. Compared by value, immutable.

foundational · js/operators

Symbols that combine values. Arithmetic, comparison, logical, ternary — the verbs of the language.

foundational · js/conditionals

`if`, `else`, `switch`, and the ternary. Branching control flow on a boolean test.

foundational · js/functions

Reusable units of behavior. Take inputs, return outputs. The fundamental unit of JS abstraction.

foundational · css

The language that styles the web — selectors, the box model, layout, and color.

foundational · css/box-model

Every element is a box: content, padding, border, margin. Master this and layout stops being mysterious.

foundational · css/flexbox

One-dimensional layout — distribute space along a row or column with gap, justify, and align.

intermediate · css/selectors

How you target elements — combinators, pseudo-classes, :is/:where/:has, and specificity.

foundational · js/arrays

Ordered, integer-indexed collections. Mutable, dynamically sized.

foundational · js/objects

Key-value collections. JavaScript's primary structured data type.

foundational · js/dom

The browser's tree of nodes representing the current page. The bridge between JS and what the user sees.

foundational · js/events

Notifications that something happened — a click, a key press, a network response. Programs subscribe with listeners.

intermediate · js/closures

A function carries its lexical scope with it. Lets you build factories, currying, and stateful callbacks.

intermediate · js/async

Sugar over promises. Reads like synchronous code, runs without blocking the event loop.

intermediate · auth

Proving who someone is. Distinct from authorization, which is what they can do.

intermediate · auth/password-hashing

Storing a one-way transform of a password rather than the password itself. bcrypt, argon2, scrypt — never SHA, never MD5.

intermediate · auth/sessions

A server-side or signed-token record that links a request to a logged-in user.

foundational · ai/prompting

Writing inputs that lead a language model to do the work you actually want. The skill that replaces "Google it" in the AI era.

foundational · ai/context-window

How much text a model can keep in mind at once. Bigger isn't always better — relevant beats abundant.

intermediate · ai/tool-use

Letting a model call external functions — file reads, database queries, API calls — to take action, not just answer.