JavaScript

Functional tests check whether code runs, not whether it looks right. Visual regression testing closes exactly that gap: screenshots of components and pages are compared against a maintained baseline, so unintended CSS changes, broken layouts and rendering bugs surface before they ever go live.

Most developers only use DevTools as a console tab. Yet Chrome DevTools hides techniques that cut debugging time in half, surface performance problems in seconds and shine a light through the entire network stack of a JavaScript project, without writing a single line of extra code.

Schema migration in IndexedDB differs fundamentally from server side database migrations: there is no migration tool, no SQL DDL commands and no central place to run scripts, only the onupgradeneeded event, a single version number, and the developer's responsibility to change object stores and indexes step by step, robustly and backward compatibly.

Anyone who wanted to group JavaScript arrays by a criterion used to reach for Lodash, Underscore, or a nested reduce() chain. With Object.groupBy and Map.groupBy, ES2024 finally brings a native, readable solution directly into the language, with a clear difference between the two that is often overlooked in practice.

Few browser features are misused as often as the Notifications API: a permission dialog fired on the very first page visit leads to permanent rejection in the vast majority of cases. Implemented correctly, with proper timing, clear context and service worker integration, the same API becomes a feature users actively request instead of dismissing on sight.

Tagged Template Literals are far more than pretty string interpolation. With a tag function in front of them, they turn into a powerful tool: SQL injection protection, safe HTML escaping, and domain-specific languages, all directly in JavaScript, without external parsers.

A Content Security Policy is the single most effective HTTP header against cross site scripting, yet most projects either skip it entirely or ship it with a far too generous whitelist. This article shows how a Content Security Policy grows from the first directive through nonces and hashes all the way to a hard enforcement mode, without suddenly breaking inline scripts or third party tools.

Generator functions are one of the most underrated JavaScript features: they produce values on demand, process infinite data streams with constant memory usage, and enable elegant asynchronous iteration, without external libraries and without promise callback chaos.

Anyone embedding JavaScript or CSS from an external CDN is trusting that the provider will never be compromised. Subresource Integrity replaces that blind trust with a cryptographic checksum the browser verifies against the actual file content before execution, making silent supply chain attacks technically visible.

Interaction to Next Paint punishes every millisecond that passes between a click and a visible reaction. Systematically identifying Long Tasks and resolving them with yielding, the Scheduler API and event handler slimming lowers the INP number not by accident, but through traceable technical interventions.