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

Execution Trees, Not More Logs: A Better Debugging Model for AI Agents

A flat log can tell you that five things happened. It often cannot tell you which operation caused... 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

Learn Number of Islands, Invert Binary Tree, and Course Schedule with Step-by-Step Visualization in DSA View View 👀👀

Hoi hoi! I’m @nyaomaru, a frontend engineer who is surprised by how cold it is in the Netherlands... 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

The board came back. The highlights lied.

I ship Codenames AI, a web game. Each game mode keeps its own save in localStorage. Reload the tab,... 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 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

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

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

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

🪪 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

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 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

A calendar library returned the same answer for every year — and my tests agreed with it

I build a Korean saju (BaZi) service. The whole pitch is that the numbers are computed... 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

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

Inside TypeScript 7's Go Port: Designing Typed AST Nodes Without a Giant Struct

A step-by-step look at TypeScript 7's Go AST design: shared node data, syntax-specific data, discriminated unions, and a small Go implementation. Read More

OpenAI Rated Its Own Model 'Critical' for Cyber Risk. Gate Your Agent.

GPT-6 Astra is the first model OpenAI rates 'Critical' for cyber capability. What that label means, and the tool-permission gate your agent needs anyway. Read More