Tutorials covering programming languages, type systems, architecture, tooling, and the patterns used to build software that lasts. Each chapter is standalone, built around real examples and verified facts.
RxJS is the reactive layer underneath Angular. Every HTTP call, every router event, every form value change, and every signal-based computation that Angular exposes is an Observable underneath. An Observable is a description of a stream — a sequence of values that arrive over time. Unlike a Promise, which produces exactly one value and resolves…
These two media features describe how a device handles content overflow — whether it scrolls, paginates, or simply clips. They’re especially relevant for paged media (like print) and e-readers. Overview of Features Feature Description Axis overflow-block Overflow handling along the block axis Vertical (in horizontal writing modes) overflow-inline Overflow handling along the inline axis Horizontal…
A single await expression waits for one future. A sequence of await expressions waits for futures one after another, but the operations themselves run sequentially — the second operation does not start until the first completes. When operations are independent, this sequential waiting is wasteful. Fetching a user profile, an order history, and a list…
When a container reaches its memory limit, the Linux kernel does not gracefully ask it to free memory. It sends SIGKILL. The process dies immediately, without cleanup, without flushing buffers, without closing connections. The container exits with code 137 (128 + 9), and docker inspect reports OOMKilled: true. This is the cgroup OOM killer, and…
Errors are a normal part of every program — files go missing, networks drop, users type nonsense, and code has bugs. JavaScript gives you a structured way to throw, catch, and handle errors so a single failure doesn’t crash the whole app. The try / catch / finally block is the foundation of that system….
The pg package, also known as node-postgres, is the canonical PostgreSQL client for Node.js. It is not a full ORM. It does not model your tables as JavaScript classes, does not manage migrations, and does not hide SQL behind a query builder. It sends SQL to PostgreSQL and returns the rows as plain JavaScript objects….
A context object on its own does nothing. It is a token — an identity that a provider and a consumer agree on. The provider gives the token a value, the consumer reads that value, and the connection between them is established by React walking the tree. Neither end knows where the other is. The…
A generic type parameter is a placeholder, but a placeholder with no constraints is nearly useless. A function that takes T without bounds can only move, borrow, and drop the value. It cannot print it, compare it, clone it, or call any method beyond what every type supports. Trait bounds are the constraints that make…
A self join is a join in which a table is joined to itself. The table appears twice in the FROM clause, and the two instances are given different aliases so the query can distinguish them. The join condition relates a row in one instance to a row in the other, which is how the…
Not every responsive concern is about screen width. A phone held upright has a different shape than the same phone turned sideways. A user who has enabled reduced motion in their operating system expects animations to be gentler or absent. A printed page has different constraints than a screen — colors may not render, interactive…