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.
A React application that fetches data from a server needs more than fetch and useState. It needs caching, deduplication, background refetching, and a consistent way to handle loading and error states. TanStack Query is the library that provides all of these, and the QueryClient is the object that holds the cache and the configuration. The…
Shared mutable state is the classic source of concurrency bugs. Two threads incrementing the same counter without coordination can produce a wrong total because the increment is three operations—read, add, write—and the threads can interleave arbitrarily . Rust does not eliminate shared state, but it makes the dangerous parts impossible to ignore. The Mutex<T> type…
A Common Table Expression is a named temporary result set that exists for the duration of a single query. It is defined with the WITH keyword, and it can be referenced by name anywhere in the query that follows. The CTE is not a view — it is not stored in the database schema —…
The View Transitions API is a browser feature that captures the old and new states of a page and animates between them. It produces smooth transitions between routes, between the themes, and between the states of a component, with the browser handling the snapshots and the crossfade. Tailwind does not ship the built-in utilities for…
A Promise is a value that will be available later. An async function returns a Promise, and await unwraps the Promise’s value. The JavaScript runtime has had these for years, and TypeScript’s types for them are precise: Promise<T> is the type of a Promise that resolves to T, async functions return Promise<T> automatically, and await…
Form validation in Vue 3 is not a built-in feature. The framework gives you reactivity and v-model, but the rules, the error state, the submission gating, and the async validation are left to the application. VeeValidate is the library that fills this gap. It is not a schema validator itself—it is the form state manager…
The previous chapter covered the developer-facing tools for change detection: the ChangeDetectorRef, the signals, and the markForCheck(). This chapter goes underneath those tools to the machinery that drives them. For most of Angular’s history, that machinery has been Zone.js — a library that patches the browser’s asynchronous APIs and tells Angular when something might have…
Dart zones are one of the most misunderstood features in the Dart language. They look simple on the surface—a way to run code in a special context—but they underpin almost every serious logging, error-handling, and observability pattern in production Dart and Flutter applications. This chapter focuses on the advanced use of zones for logging, diagnostics,…
A Docker Swarm service is not a container. It is a declaration of intent. When you create a service, you are telling the Swarm manager what the cluster should look like—how many instances of an image should be running, how they should be networked, and what policies govern their lifecycle. The manager then works continuously…
Design patterns are reusable solutions to common problems. They’re not algorithms — they’re templates for structuring code that have proven themselves across many projects. In JavaScript, some patterns are more relevant than others because the language handles certain things natively. The patterns worth knowing in JavaScript fall into three groups: creational (how to make objects),…