Floating Point: Why Your Money Is Wrong
Every answer here is decidable by IEEE 754 and ECMA-262. No opinions, no engine trivia. Binary fractions, the lies toFixed tells, negative zero, the gaps above...
Quizzes
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Where Data Lives: Frontend Data-Fetching & State Architecture
The biggest architectural decisions in a modern frontend are about where data lives and when it's fetched. Start by separating server state (an async cache of data you don't...
Game Theory in Awkward Situations
Thirty-five questions on strategic behavior in everyday human situations — splitting the bill, replying late, group projects, salary talks, and office politics — using them to...
Git Disaster Recovery Without Panic
Thirty-three realistic Git recovery problems. Practice reading reflogs and saving lost commits, including work left on detached HEAD. Learn which undo command fits the...
Hello, Goodbye, and Thank You Around the World
A globe-trotting, slightly silly tour of the three phrases every traveller actually needs — hello, goodbye, and thank you — across 40-plus languages. Each question pairs the...
How Mechanisms Work: What Happens When This Turns?
Rotation goes in; something surprising comes out. A differential lets two wheels turn at different speeds while both are driven, a Geneva drive turns smooth rotation into...
Designing an HTTP API (REST, Done Right)
Most "REST" APIs are RPC in disguise. This quiz sharpens the decisions that matter when other people build against your endpoints: method safety and idempotency,...
Real-Time over HTTP/2 & HTTP/3: Multiplexing, QUIC & WebSocket Bootstrapping
How HTTP/2 multiplexing, HTTP/3 over QUIC, and Extended CONNECT (RFC 8441/9220) reshape real-time delivery: application- vs transport-level head-of-line blocking, QUIC's...
Idempotency, Retries & Delivery Guarantees
Networks fail mid-request, so real systems retry — and retries are where correctness quietly breaks. Build intuition for at-least-once vs. at-most-once vs. 'exactly-once' (and...
Infrastructure You Walk Past
A photo-based field guide to the machinery on every street corner: transformers, cutouts, cell sites, hydrants, backflow preventers, cathodic protection posts, manhole covers,...
p50, p95, p99: What Averages Hide
Your average response time is 120 ms and your users are angry. This Quiz is about the gap between those two facts: how latency distributions really look, which statistics...
LLM Mechanics: Tokens, Context, and Cost
A practical quiz about how LLM APIs handle tokens, context, sampling, caching, streaming, structured output, and knowledge cutoffs. It includes production scenarios and cost...