TypeScript Coffee

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

Dev log #19 WebRTC v2 flows, agentic orchestration, and a perfectly synced vault

This week was a high-output sprint across the stack—from low-level p2p networking in Python to... 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

Learn Valid Parentheses, Reverse Linked List, and Tree Max Depth with Step-by-Step Visualization in DSA View View 👀👀

Hoi hoi! I’m @nyaomaru, a frontend engineer who struggles to make game sounds. 😿 Have you used DSA... 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

Delta encoding multiplayer game state

Old Light is a browser strategy game where a tab can stay open for days. The client holds a full copy... 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

I’m Looking for the Right Problem, Not the Right Job Title — Could It Be You?

This is a slightly unusual post. After almost 20 years of writing software, creating and leading an... 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

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

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

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

Your birth time is lying to you: a time-zone rabbit hole in a Chinese astrology calculator

I built a calculator for BaZi — Chinese "Four Pillars" birth charts. Whatever you think of the... Read More

Build a Mini Engineering Graph With TypeScript and GitHub

You inherit a codebase. A file called checkout.ts is causing problems. You ask three... Read More

I Built a Password Strength Calculator That Never Sends Your Password Anywhere Here's the Entropy Math

Type Your Real Password Into a Random Website. What Could Go Wrong? Go search "password... Read More

I built an e-signature app that charges you for storage, not signatures

The bill that made no sense A signature is about 400 bytes of JSON and a hash. Every big... Read More

I failed a "design a document editor" interview, so I built one

Every resume builder is a form. Building the actual editor meant event sourcing, a page-break planner, and a PDF that matches the screen exactly. 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

🐸 I Built a Mini Compiler From Scratch, Here's What I Learned

Compilers always felt like this mysterious black box to me. Code goes in, magic happens, a program... 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 Built a Tax Engine for 5 Countries on Cloudflare Workers. It Went About as Well as You'd Expect.

I have a folder on my computer called tax-shit. It contains 47 PDFs from five different tax... Read More