Notes & write-ups

Things I've thought about long enough to write down.

Contents

2026

How Holiday Optimizer plans your time off 27 Sep

The small dynamic program behind it, why the holiday calendar is harder than the algorithm, and what happened when the press found it.
How to use the Lichess puzzle database 27 Sep

Download the Lichess puzzle CSV, stream it in TypeScript, pull out mate-in-2 puzzles by theme and rating, and check every solution with chess.js.
How many videos can you upload a day with the YouTube API? 27 Sep

Since June 2026, uploads have their own quota: 100 a day. What each call costs now, why older answers say six, and how to work out your real limit.

JavaScript — Using The Spread Operator (…) 18 Mar

A simplified look at how to use the Spread Operator (…) in JavaScript: in function calls, arrays and objects, and why the copies it makes are shallow.