TypeScript Coffee

7 New JavaScript Features (And 2 I'm Still Waiting For)

Remember how I promised you (or rather myself) two weeks ago that from now on I'd only write light,... Read More

You’re a Real TypeScript Developer Only If...

A few months ago, I published You're a Real JavaScript Developer Only If... It was just a post for... Read More

TanStack Start Is Kind of a Big Deal

Introduction People keep telling me TanStack Start is kind of a big deal, and I wanted to... Read More

After 7 Next.js 16 Caching Bugs, I Stopped Guessing and Built a System

There's a specific feeling you get after your third production caching incident. It's not panic.... Read More

Why My Analytics Was Logging Every Page Visit Twice (And How I Fixed It)

I built a custom analytics system into my portfolio backend — a Django REST API that records page... Read More

Making my TypeScript types 15.7x faster

What slows large TypeScript types down, how to measure it with @ark/attest, and the one-field match that made my schema library 15.7x cheaper to type-check. Read More

The Hidden Machinery Behind Background Jobs

This will be a boring article today, but I wanted to write it after talking to a developer who... Read More

Conduit: The Gateway I Built to Forget About

I've been trying to keep my publishing schedule to one article a week, but this one felt too special... Read More

TypeScript Tips That Actually Matter in Real Projects (including the satisfies operator)

Most TypeScript tutorials teach you the language. This article teaches you how to use it. There's a... Read More

TypeScript Patterns for Environment Variables

Yesterday, as I was working on a CORS configuration, AI generated a block of code for me: const... Read More

Mastering the Latest TypeScript: What's New in 6.0 (and a Peek at 7)

TypeScript 6.0 has been out for a few months now, and it's a bit of an unusual release. It's the last... Read More

CHANGELOG.md is for Both Humans and AI Now, So Let’s Automate It

Hoi hoi! I’m @nyaomaru, a frontend engineer who recently discovered the deliciousness of a cheese... Read More

Building One Knowledge Graph Across 46 Repositories With Static Analysis (Part 1)

A static-analysis approach to unifying 46 repositories (37 air-closet-side + 9 mall-side) of legacy production code into one knowledge graph. Why simply 'letting AI read the code' isn't enough, why I had to chase down boundary nodes (API endpoints, DB tables, Event topics), how I dealt with framework and library diversity, and what 3 months of trial and error solved or didn't solve — looking back through actual git history. Read More

Every Alarm Is a Crime Scene: Meet Poirot, the Read-Only Incident Detective

What if the thing that gets paged at 2am wasn't a person, but a detective that investigates the... Read More

The Playwright Playbook — Part 3: Multi-User, Multi-Tab & Browser Context Testing

Test real-time collaboration, role-based permissions, and multi-tab flows in Playwright. Two users. One test. The scenarios most frameworks simply can't handle. Read More

The Playwright Playbook — Part 7: The CI/CD Setup Nobody Shows You

A production-ready Playwright CI/CD pipeline — GitHub Actions, test sharding across machines, browser matrix, Docker for consistent environments, Slack failure notifications, and published HTML reports. Read More

I gave 8 AI agents an island and watched a society emerge — wars, gossip, grudges, and peace

Tiny Civilization: what happens when AI agents have to live together I grew up on Age of... Read More

From Transcript to Typed Action Items: Three Parallel Agents in TypeScript

Most meeting summarizers cram summary, action items, and sentiment into one LLM prompt. Here's a cleaner TypeScript shape: three specialist agents run in parallel, two return typed Zod output, and an aggregator merges them into one report. Read More

The Playwright Playbook — Bonus: Refactoring Schema Validation with Zod

A reader asked for it — here's the hand-rolled schema validator from Part 4, refactored with Zod. Better error messages, free type inference, way less boilerplate. Read More

How to Validate Environment Variables Without a Library (And Why You Should Anyway)

I'll show you a complete env validation setup in 50 lines of TypeScript, then explain when and why you'd reach for a library instead. Read More

The Playwright Playbook — Part 1: Stop Writing Playwright Tests Like a Beginner

7 beginner mistakes that are quietly destroying your Playwright test suite — and the professional TypeScript patterns that fix them. Real before/after code included. Read More

Your Evals Are Flaky Too: Stop Trusting a Pass Rate You Can't Reproduce

Your agent is non-deterministic and you know it. So is your model-as-judge eval. Here's how to measure judge flakiness, treat UNSTABLE as a first-class failing state, and use the trace to tell a random judge apart from a drifting harness. Read More

The Bug That Passes Every Toolchain Check: Circular Dependencies in JavaScript

Circular dependencies compile cleanly, pass tests, and ship to production. Here are the 3 patterns that create them, what Node.js, webpack, Rollup, and esbuild actually do with them, and how to stop them before they compound. Read More

A Free Screenshot Editor That Never Uploads Your Image

A free screenshot and image editor that runs entirely in your browser. Keeping every edit reversible and handling big phone photos, in plain TypeScript and Canvas2D. Read More