From the OpenReplay Blog
Formatting Dates and Numbers with the Intl API
Build accurate mental models of Intl.DateTimeFormat and Intl.NumberFormat, including rounding modes, Temporal types, and range formatting in JavaScript.
Singletons in JavaScript: Useful Tool or Hidden Trap?
ES module singletons break across Jest, microfrontends, and web workers when mutable state is involved, and this breakdown explains how to avoid those pitfalls.
What Code Coverage Really Tells You
Code coverage metrics in Vitest and Jest measure execution, not correctness. See why high percentages mislead and how branch coverage reveals real test gaps.
Choosing a Better Bookmark Manager
Compare bookmark managers by sync model, data ownership, and longevity to choose between Raindrop.io, Pinboard, and self-hosted tools like Linkwarden.
The URLPattern API: Matching URLs the Modern Way
The URLPattern API matches and parses URLs using named groups instead of regex. See how it works in browsers, service workers, and SPA routing logic.
How to Add a Simple Snowfall Effect to Your Website
Build a canvas snowfall effect that respects reduced motion preferences, pauses in background tabs, and keeps holiday animations performant and accessible.
Building a Holiday Countdown Timer in JavaScript
Build a JavaScript holiday countdown timer that avoids setInterval drift, handles time zones correctly, and stops cleanly when the target date passes.
jQuery Alternatives for Modern JavaScript
Compare jQuery to vanilla JavaScript, Cash, Alpine.js, and React to choose the right tool and eliminate unnecessary dependencies from your project.
Five Modern ORMs Developers Should Have on Their Radar
Compare Prisma, Drizzle, TypeORM, MikroORM, and Kysely across type safety, bundle size, edge compatibility, and migration workflows to choose the right ORM.
Preventing Layout Shift with Modern CSS
Prevent layout shift by applying intrinsic sizing, metric-aligned font fallbacks, and compositor-safe animations to keep CLS scores below 0.1.
Making Sense of Type Narrowing in TypeScript
Build a mental model of TypeScript type narrowing, control flow analysis, discriminated unions, and user-defined type guards to eliminate type errors.
How to Generate & Embed QR Codes
Generate reliable QR codes in JavaScript using SVG or Canvas output, and avoid scan failures caused by quiet zones, contrast issues, and logo overlays.
Getting Creative with CSS Shape Functions
The CSS shape function creates responsive clip paths and motion paths using percentages, replacing fixed pixel coordinates that break when containers resize.
How to Fix '429 Too Many Requests' in Your Web App
Fix HTTP 429 Too Many Requests errors by applying frontend throttling, exponential backoff, retry logic, and rate limit header parsing in your web app.
Common Patterns for Configuring Node.js Projects
Node.js project configuration patterns for runtime pinning, lockfiles, ESM, TypeScript, and ESLint flat config help you make intentional setup choices.
The Most Useful MCP Servers for AI-Powered Development
MCP servers connect AI models to files, Git history, and live data. See which servers improve frontend development workflows using standardized tool access.
Smart Loading Patterns with htmx
Build faster dashboards by applying htmx loading patterns like lazy loading, viewport triggers, and progressive enhancement to defer slow queries effectively.
What Actually Belongs in the Head of Your Document
Know exactly what belongs in the HTML document head, from charset and viewport to social metadata, resource hints, and structured data ordering.
The Benefits of Using Strict Mode in Modern JavaScript
JavaScript strict mode rules, ESM automatic activation, and safer this binding help you prevent errors and debug legacy code with confidence.
Tools to Keep Your Node.js Projects Clean and Up to Date
Keep Node.js projects secure and current using Renovate, Dependabot, nvm, and audit tools to manage dependencies, runtime versions, and vulnerability drift.
Making Sense of Code Changes with diff
Interpret unified diff format, Git diff commands, semantic tools like Difftastic, and AI-assisted summaries to review frontend code changes with confidence.
Reactivity Without a Framework: What Native JS Can Do Today
Proxy, EventTarget, and browser observers enable reactive UI state tracking and DOM updates in vanilla JavaScript without shipping framework dependencies.
Drawing Layout-Friendly Shapes with the CSS xywh() Function
The CSS xywh() function defines rectangles with position and dimensions for responsive clip-path layouts. See how it compares to inset() across modern browsers.
How to Create and Publish an npm Package
Create and publish an npm package using ESM, TypeScript, and npm Trusted Publishing with GitHub Actions OIDC for secure, tokenless automated releases.