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Resource Hints — preload, prefetch, preconnect & Speculation Rules

Jul 27, 202628 min read

Resource Hints — preload, prefetch, preconnect & Speculation Rules

One line of HTML can tell the browser to resolve a DNS lookup, warm a connection, or fetch a critical file before the parser even finds it. But a font preload without crossorigin silently downloads twice, over-preloading delays your LCP, and rel=prerender is dead. This guide maps all five hints to network phases, covers the fetchpriority attribute in full, the direct LCP/INP Core Web Vitals impact (measurable in Search Console), CDN/edge auto-hints via 103 Early Hints, framework auto-hints for Next.js/Astro/Nuxt/SvelteKit, an audit of anti-patterns to remove, and the Speculation Rules API that replaced prerender.

JavaScript Iterator Helpers: Lazy map/filter/take (With Live Tracer)

Jul 27, 202621 min read

JavaScript Iterator Helpers: Lazy map/filter/take (With Live Tracer)

CSS Scroll-Driven Animations: scroll(), view() & Zero JavaScript

Jul 27, 202622 min read

CSS Scroll-Driven Animations: scroll(), view() & Zero JavaScript

Latest Articles

The Temporal API: Finally Fixing JavaScript Dates (With Live Playground)

The Temporal API: Finally Fixing JavaScript Dates (With Live Playground)

JavaScript's Date object has been broken for thirty years — mutable, zero-indexed months, and timezone handling that changes between browsers. The Temporal API fixes all of it. This guide has a live playground: watch Date mutate under you while Temporal stays frozen, pick the right type for any job, handle DST ambiguity with earlier/later/reject instead of silent wrong answers, plus a bundle-size showdown vs moment/date-fns/dayjs/Luxon, moment.js migration recipes, the definitive Instant-vs-ZonedDateTime storage pattern for backends, TypeScript patterns, and the Node.js/edge runtime support matrix.

CSS @layer: Cascade Layers That End the Specificity Wars

CSS @layer: Cascade Layers That End the Specificity Wars

Cascade layers let you declare which groups of styles win — independent of selector specificity. A one-line @layer declaration replaces years of specificity hacks and !important escalation. This guide covers the full system: layer ordering, why unlayered styles beat every layer (the Tailwind v4 upgrade bug), the mind-bending !important reversal, taming third-party CSS with @import layer(), nested layers, revert-layer, Shadow DOM's independent layer graph, design system layer contracts for Radix/shadcn/MUI/Chakra, the empty-layer reservation pattern for code-split apps, and the migration path that can't break anything.

Schema Markup & Structured Data — JSON-LD That Actually Works

Schema Markup & Structured Data — JSON-LD That Actually Works

Schema markup tells Google and AI engines exactly what your content means, not just what it says. This guide covers JSON-LD by type with required properties, the content-parity rule that keeps you off Google's manual-action list, the @graph entity pattern, sameAs for the Knowledge Graph, the current reality after FAQ and HowTo rich results were removed, plus Recipe/LocalBusiness/JobPosting deep-dives, the Merchant Listings shipping+returns update, the HowTo migration path, and the CMS-schema-drift trap that breaks WordPress sites.

Meta Tags for SEO & Social — Open Graph, Twitter Cards & SERP

Meta Tags for SEO & Social — Open Graph, Twitter Cards & SERP

A dozen lines in the <head> decide whether your link shows a rich card with a wide image or a bare blue URL nobody clicks. This guide covers the SEO title and description, Open Graph and Twitter Card tags, the absolute-URL trap that silently breaks previews, pixel-width truncation, how to force a re-scrape when the old preview won't update, how Perplexity/ChatGPT/Google AI Overviews use your tags for citations, Article JSON-LD paired with meta, dynamic OG image generation, per-platform unfurl quirks (Discord/Slack/WhatsApp/iMessage/Bluesky/Mastodon), Google Discover eligibility, and the canonical + noindex conflict.

requestAnimationFrame: Smooth 60fps Animation (With Live FPS Demo)

requestAnimationFrame: Smooth 60fps Animation (With Live FPS Demo)

Every requestAnimationFrame tutorial claims it is smoother than setInterval, but none show it happening. This guide runs rAF and setInterval side by side with live FPS counters, then reveals the bug nobody demos: fixed-per-frame animation runs twice as fast on a 144Hz screen. Fix it live with delta time, cap the frame rate, kill the cancelAnimationFrame memory leak, plus WAAPI vs rAF decisions, the React useAnimationFrame hook, Chrome DevTools + Long Animation Frames API for INP debugging, IntersectionObserver-gated loops, and prefers-reduced-motion accessibility.

Native CSS Nesting: Sass Syntax With No Build Step (And One Big Trap)

Native CSS Nesting: Sass Syntax With No Build Step (And One Big Trap)

Native CSS nesting brings Sass-style nested rules to the browser with zero build step — and it's Baseline in every evergreen browser. But it isn't a Sass clone: the parent selector gets wrapped in :is(), which silently changes specificity in ways that break Sass habits; &__ concatenation doesn't exist; and bare compound selectors gain an unwanted space. This guide covers every & placement, nesting at-rules inside components, the honest Sass migration map, plus @scope pairing, Tailwind v4 native output, @starting-style composition, the .vue/.svelte/.astro scoped-CSS interaction, and the & + & flow-content pattern.

CSS :has() Selector: The Parent Selector, Explained With Live Demos

CSS :has() Selector: The Parent Selector, Explained With Live Demos

For twenty years, a parent selector was the most requested CSS feature — and :has() finally delivered it. Style a card because it contains an image, select the element before a hovered one, restyle a grid by how many children it holds, build form validation and dark mode toggles with zero JavaScript. This guide covers every pattern plus the specificity trap, the no-nesting rule, the two-negatives (`:not(:has())` vs `:has(:not())`) confusion, CSS-only tabs, `<details>` accordions, state-machine buttons, the shadow-DOM scope boundary, and the performance constraints that matter.

The File System Access API — Save to Disk, Directories & OPFS

The File System Access API — Save to Disk, Directories & OPFS

The File System Access API lets a web app edit a real file on disk and save changes back in place — the thing that makes an in-browser editor feel native. This guide covers open/save/Save-As, reading directories, atomic writes, persisting handles across sessions, OPFS with SQLite-WASM, the new File System Observer API for watching external changes, drag-drop into directory handles, keepExistingData for random-access edits, PWA file_handlers for OS-level 'Open with', and the honest Firefox/Safari fallback story.

Polling vs WebSockets vs SSE: The Real-Time Guide

Polling vs WebSockets vs SSE: The Real-Time Guide

Everyone defaults to WebSockets for real-time. Most shouldn't. This guide runs polling, WebSockets, and Server-Sent Events in a live side-by-side simulator so you can see polling waste requests, SSE stream over one HTTP connection, and WebSockets talk both ways. Plus Node.js ws server code, socket.io vs raw WS, LLM streaming with Fetch + ReadableStream, WebSocket authentication, serverless timeout limits (Vercel, Netlify, Cloudflare Workers), pub/sub scaling with Redis, jittered reconnection backoff, and the production bugs — proxy buffering, HTTP/1.1 six-connection limit, silent WebSocket death — that bite every team.