Tutorials covering the frameworks and libraries that shape how modern applications are built — Angular, React, Vue, and the ecosystem tools that surround them. Each chapter is standalone, built around real examples and verified facts.
Cypress is the E2E testing framework that the Angular team officially recommends for end-to-end testing. It runs in a real browser, executes the test code in the same run loop as the application, and provides a test runner that shows exactly what happened at every step. The ng add @cypress/schematic command is the official Angular…
Batching is the mechanism by which React groups multiple state updates into a single re-render. Before React 18, batching was limited to updates inside React event handlers. An update inside a setTimeout, a promise callback, or a native event listener triggered a separate render for each update. React 18 extended batching to all update sources,…
Angular DevTools is a browser extension that provides debugging and profiling capabilities specifically for Angular applications. It integrates directly into Chrome and Firefox developer tools, adding an “Angular” tab that exposes the framework’s internal state in a way that generic browser DevTools cannot. The extension is maintained by the Angular team and is available for…
A React memory leak is not a failure of React’s garbage collection. React unmounts the component, removes its DOM, and drops its internal references. The leak persists because something outside React still holds a reference to the component’s state, its DOM nodes, or its closures. The common sources are timers, event listeners on window or…
A bug appears in an Angular application. The component does not render. The signal does not update. The HTTP request returns the wrong data. The route does not activate. The change detection cycle does not run. Debugging is the process of finding the cause and fixing it. Angular provides a set of tools and techniques…
React does not attach event listeners to the DOM elements you write in JSX. It attaches a single listener per event type to the root container, and when a native event fires, React walks its internal Fiber tree to find the components that have handlers for that event, then calls them with a SyntheticEvent—a cross-browser…
The Angular Language Service is the tool that gives editors and IDEs a real understanding of Angular templates. Without it, an HTML file is just text. With it, the editor knows that user in {{ user.name }} refers to a component property, that app-user-card is a component selector, and that binding to an unknown property…
Hydration mismatches occur when the HTML generated by the server does not match what React expects during the client’s initial render. React’s hydrateRoot treats this as a bug, not a feature. In development, it warns about the mismatch; in production, it may fall back to client rendering from the nearest Suspense boundary, which discards the…
An Angular application runs in more than one place. It runs on a developer’s laptop, on a staging server, and in production. Each environment has different settings: a different API URL, a different feature flag state, a different logging level. The application code should not change between environments. Only the configuration should. Environment configuration is…
Hydration has historically been an all-or-nothing operation. The server sends HTML, the browser parses it, and React attaches event handlers to the entire tree before any part of the page becomes interactive. In a large application, the JavaScript bundle can be hundreds of kilobytes, and the main thread can be blocked for hundreds of milliseconds…