TypeScript Coffee

What If Your AI Agent Never Had to Leave the Browser? (Demo 🚀)

I haven't written anything lately because, honestly, I just didn't have the headspace for it. There... Read More

Learn Trapping Rain Water, Top K Frequent and Selection Sort with Step-by-Step Visualization in DSA View View 👀👀

Hoi hoi! I’m @nyaomaru, a frontend engineer who has been obsessed with ramen lately. 😸🍜 Have you... Read More

TypeScript Compiler API: Preserving Child Node Narrowing in Reusable Type Guards 🔧

Hoi hoi! 👋 I'm @nyaomaru, a frontend engineer exploring new possibilities with Jev 😸 (I'm also... Read More

Why Your TypeScript Code Still Crashes in Production

A practical visual guide to the TypeScript mental model. Discover why types vanish at runtime, how structural typing works, and how to write clean, type-safe code that never crashes in production. Read More

Your Type Guard Can Silently Drift from Your TypeScript Type 🔧

Hoi hoi! 👋 I'm @nyaomaru, a frontend engineer just back from a short vacation on Texel, a small... Read More

Would You Choose a Library Because AI Writes It Better?

I was at a conference recently and watched Joel Hooks talk about Effect. Effect homepage h1... Read More

TS Evidence Graph: Make Every SKILL Instruction 100% Enforced

TL;DR Write the rules into AGENTS.md or a skill file and the agent still will not follow... Read More

Migrating a Real TypeScript OSS Library from tsup to tsdown

The config migration was small. Preserving the package contract was the interesting part. Hoi hoi!... Read More

Jev vs Claude: Who Wins?

I did not need Jev to beat Claude or Kimi on a benchmark. I needed to know whether I could trust it... Read More

NestJS Testing Module: Provider Overrides (with Cheat Sheet)

A complete guide to NestJS's testing module: how overrideProvider really wires mocks, why get() fails on scoped providers, and using useMocker. Read More

I missed Go's `if err != nil`, so I built errval for TypeScript

I write mostly TypeScript and some Go. When I switch back from Go, I miss explicit error returns. A... Read More

AsyncLocalStorage vs Request-Scoped Providers: The DI Trap That Taxes Latency

Here's a logger. It's a dozen lines and it looks completely harmless: request-logger.ts import {... Read More

I Turned My Editor Into a Pokémon World That Levels Up When I Actually Ship

Repo: https://github.com/UribeJr/pokedev Most editor pets are wallpaper. Cute? Sure. Connected to... Read More

addDays() Mutated a Date Three Components Away From Where I Called It

A date utility that calls .setDate() and returns the same object looks pure. It isn't — Date is mutable, so the caller and everyone else holding that reference get changed out from under them. Temporal, now shipping in real browsers, fixes it by making dates immutable. Read More

TypeScript 7 Is Up to 10x Faster. Should You Upgrade Now?

Benchmark TypeScript 7 safely, compare real project results, and find compatibility problems before changing your main branch. Read More

I Killed My Electron App Twice to Test Crash Recovery

"We have crash recovery" is an easy thing to claim. I wanted to know what happens if the process... Read More

🪪 Avatar RS: Very Efficient Avatar Components for WASM Frameworks

Bien le bonjour 👋! Every WASM app eventually needs an avatar. Profile pictures, user cards,... Read More

NestJS Guards: CanActivate, ExecutionContext & Reflector

A complete guide to NestJS guards: how CanActivate, ExecutionContext, and the Reflector decide who reaches your route handler, with a cheat sheet. Read More

How to Build a Task Management App with React & TypeScript

Hey everyone, it's Sadee! If you've ever wanted to build a cool task board where you can move... Read More

A browser arcade in plain TypeScript: 8 classic games, 35 kB, no framework

Play it: https://minjia-hu.github.io/retro-arcade/ Source:... Read More

What Protobuf descriptors don't tell you: building a generic mock generator

I built a library that generates mock data for any Protobuf message without per-message code. The schema walk was the easy part — here are the four things that actually bit me. Read More

Three PRs to Rowboat in 24 Hours, One of Them Taught Me More Than the Others

Last month I wrote about how I use coding agents to build things. This week I pointed the same setup... Read More

Three ways I miscounted my own AI agents, and what the transcripts actually say

Claude Code writes a JSONL transcript for every session, and another one for every subagent it... Read More

I added a type-checked pipeline operator to TypeScript — including TSX

A proof-of-concept TypeScript compiler with a pipeline operator. I searching testers and... Read More