you used to know this stuff. let's keep it that way.
a 4-minute daily quiz on your stack, what changed in your ecosystem this week, and your own code. for developers who ship with AI but still want to know what the code does.
// core · output · javascript · ★★
what does this print?
- 1
[1, 3, 10] - ✓
[1, 10, 3] - 3
[10, 3, 1] - 4
TypeError
default sort compares strings: "10" < "3". pass (a, b) => a - b.
three rounds
core
fundamentals at your level
syntax, semantics, complexity, debugging instincts — the stuff autocomplete quietly takes over.
changelog
what changed, and why
from real release notes. never "which version shipped tuesday" — always "what does this replace?"
repo
your own code
questions about the PRs you (and your agents) merged. private, never ranked.
// why: in Anthropic's 2026 randomized study of developers learning a new Python library, people who delegated to AI scored lower on a follow-up comprehension quiz — the biggest gap was debugging — while people who used AI to ask conceptual questions kept their learning. read the study. unprompted is the daily rep that keeps you in the second group.
leaderboards by city, stack and friends · 8 editor color schemes · vim keys if you want them · privacy