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.
An effect is a function that runs when the signals it reads change. It is the escape hatch from the signal graph to the imperative world — the place where a signal’s change is translated into a side effect that is not a value: a DOM update, a log, a persistence write, an external API…
The scale() and scale3d() functions let you resize elements — making them larger or smaller — without affecting the layout of surrounding elements. Overview of Functions Function Dimensions Values Description scale() 2D s or s1, s2 Uniform or separate X/Y scaling scale3d() 3D s1, s2, s3 X, Y, and Z scaling 1. scale() — 2D…
A unit test is a small program that exercises one piece of the code and asserts the expected result. The package:test is the standard testing framework for the Dart, and it provides the test function, the group function, the expect function, and the matchers. The framework runs the tests, collects the results, and reports the…
The Docker daemon is the background process that builds, runs, and manages every container on the host. It listens on the socket, pulls the images, starts the containers, and writes the logs. By default, it works well enough for the basic use, but the production environment demands the control over the logging, the storage, the…
Regular expressions (regex) are patterns for matching text. They look cryptic at first — /^\d{3}-\d{4}$/ — but they’re the most powerful way to search, validate, and transform strings. Every language has them, and JavaScript’s are among the most capable. Key point: A regular expression is an object that describes a pattern. You can create one…
A database query is expensive. It travels the network, the database parses the SQL, the planner picks the plan, the engine reads the pages, and the results return over the wire. The whole trip takes the milliseconds, and the same query runs thousands of times. The result rarely changes. The cache stores the result, and…
A custom hook is a black box. The component calls useOnlineStatus() or useFetch(url) or useFormInput(initial), and the hook does its work behind the abstraction. When the hook works, the abstraction is a blessing: the component is clean, and the logic is in one place. When the hook misbehaves, the abstraction is a curse: the React…
A closure is an anonymous function that can capture the variables from the scope where it is defined. It is the fundamental tool for the higher-order functions, the callbacks, and the concise inline logic. The |x| x + 1 is a closure that takes the x and returns the x + 1, and unlike the…
NULL is not a value. It is the absence of a value. It does not equal anything—not even itself. It does not compare greater or less than anything. It propagates through arithmetic and string operations, turning everything it touches into NULL. This behavior is correct according to the SQL standard, but it is inconvenient in…
A layout written with margin-left and margin-right is a layout that assumes every reader reads from left to right. For Arabic, Hebrew, Persian, and Urdu speakers, the assumption is wrong. The text flows from right to left, the sidebar that sits on the left in English should sit on the right, and the padding that…