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 watcher runs a side effect. The side effect may be asynchronous: a fetch that is in flight, a timer that is set, a subscription that is created. When the watched source changes before the side effect completes, the old side effect should be cancelled. The cleanup is the mechanism. The watch() and the watchEffect()…
Routes aren’t always open. Some pages require login, some need a specific role, some should prompt before navigating away with unsaved changes. Route guards are the functions or classes that decide whether navigation proceeds. They run before the route activates (or deactivates), return true or false (or a UrlTree for a redirect), and can be…
These two properties control how flex items grow to fill available space and shrink when there isn’t enough space. They’re essential for creating flexible, responsive layouts. Overview of Properties Property Description Default Values flex-grow How much an item can grow relative to siblings 0 Number (e.g., 1, 2, 3) flex-shrink How much an item can…
A class can extend only one class. Dart has no multiple inheritance. But an application often needs to share behavior across classes that are not related by inheritance. A Logger might need to be mixed into a service, a repository, and a controller. These classes do not share a superclass, and forcing them into one…
A container’s writable layer is ephemeral. When the container is removed, everything written inside it is gone. This is by design—it makes containers disposable and reproducible. But real applications need persistence: a database must survive a restart, a log file must be available after the container stops, a configuration file must be shared with the…
SVG provides several elements for creating shapes and lines. This chapter covers four essential SVG elements: <ellipse>, <line>, <path>, and <polyline>. Each serves a unique purpose in vector graphics. Overview of SVG Shape Elements Element Purpose Key Attributes <ellipse> Elliptical/circular shapes cx, cy, rx, ry <line> Straight line x1, y1, x2, y2 <polyline> Connected straight…
JSON is a lightweight data interchange format — easy for humans to read and write, and easy for machines to parse and generate. It’s the standard for sending data between a client and a server. A Quick Look at the Examples a. What is JSON? JSON (JavaScript Object Notation) is a lightweight data interchange format….
A web framework is a layer of abstraction over something simpler. Underneath Express, Fastify, Koa, and Hono, there is a module that accepts a TCP connection, parses the HTTP request, and writes the HTTP response. That module is node:http. Understanding it is understanding what the frameworks do, what they hide, and what they cost. The…
Two fields in package.json control dependency resolution when the default behavior does not produce the tree the project needs. peerDependencies declares what a package expects its consumer to provide, and peerDependenciesMeta marks specific peers as optional. overrides forces a specific version of a package anywhere in the dependency tree, including transitive dependencies that the project…
The previous chapter covered controlled inputs for the basic field types: text, checkbox, radio, and the general pattern of binding value to state and onChange to an updater. This chapter focuses on two elements that behave differently in React than they do in plain HTML: <textarea> and <select>. In HTML, a textarea’s value is its…