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 conditional type in TypeScript has the shape T extends U ? X : Y — if T is assignable to U, the type resolves to X, otherwise to Y. That much is straightforward. The subtlety is what happens when T is a union. TypeScript does not evaluate the conditional once against the whole union….
A modal dialog has a layout problem. It needs to appear centered on the screen, above everything else, with a backdrop that covers the entire page. If the modal is rendered inside a deeply nested component, its parent’s CSS can interfere: an overflow: hidden, a transform, a z-index stacking context, or a position: relative ancestor….
Every Observable in RxJS is either cold or hot, and the distinction determines what happens when more than one subscriber arrives. A cold Observable creates a new producer for each subscriber — two subscribers to an HTTP call send two requests, and two subscribers to an interval create two timers. A hot Observable shares a…
The transform property is one of the most powerful tools in CSS. It lets you rotate, scale, skew, and translate elements — all without affecting the layout of other elements. What is the transform Property? The transform property applies 2D or 3D transformations to an element. Unlike properties like margin or position, transforms don’t affect…
The dart:io library is the bridge between a Dart program and the operating system. It provides the File class for reading and writing files, the Directory class for creating and listing directories, and the FileSystemEntity base class that both inherit from. The library is available on the Dart VM and in Flutter, but not in…
A microservices application has several services, and each one has its own codebase, its own dependencies, and its own runtime. Running the whole stack locally is the daily reality of a developer working on one of those services. The naive approach is to run the service under development with a local toolchain and run the…
Arrays come with dozens of built-in methods — the day-to-day tools that make JavaScript expressive. Some mutate the array in place; others return a new array or a value. Knowing which is which, and when to use what, is the difference between clean code and buggy code. Key point: Every array method falls into one…
Prisma is a next-generation ORM for Node.js and TypeScript that takes a different approach from the traditional ORMs. It is built around a declarative schema file, a generated type-safe client, and an integrated migration system. The schema is the single source of truth: it defines the data models, the relations, and the database connection, and…
useCallback is the function-specific version of useMemo. It returns a memoized function that only changes identity when its dependencies change. The comparison is the same: on every render, React compares the dependency array, and if the dependencies are unchanged, it returns the same function reference from the previous render. If a dependency has changed, it…
The ‘static lifetime is the longest lifetime in Rust. It means “valid for the entire duration of the program,” and it is the lifetime of every string literal, every global constant, and every value that is stored in the binary itself. The annotation appears in three distinct contexts, and the three contexts have different meanings….