The Node.js Event Loop: libuv Phases, Timers & nextTick
Step through the server-side event loop, the one libuv runs — not the browser model. Walk the phase cycle (timers, pending callbacks, poll, check, close), then settle the...
Quizzes
Browse the public Catalog and filter quizzes by Tag.
Filter by tags
Select tags
Node.js Streams & Backpressure
Readable, Writable, and Transform streams, .pipe() vs stream.pipeline(), what backpressure actually protects, and how object mode changes the rules. Every answer is verified by...
Offline & Local-First Design
A local-first app treats the network as an enhancement, not a requirement. Work through service-worker caching strategies (cache-first, network-first, stale-while-revalidate),...
Project Management Failure Modes
A scenario-based Quiz about why projects slip, grow, stall, or become confusing. Each Question names a recognizable project smell and uses the Explanation to teach the...
Rate Limiting & Backpressure
When demand outruns capacity, a system either sheds load gracefully or collapses. This quiz walks the full path: the algorithms (token vs. leaky bucket, fixed vs. sliding...
Real-Time Delivery: Polling → SSE → WebSockets
"Make it real-time" hides a ladder of escalating tradeoffs. Climb it: short polling, long polling, Server-Sent Events, and WebSockets — when each is the right tool, what they...
Real-Time Delivery: Polling, Long Polling, SSE & WebSockets
When to reach for short polling, long polling, Server-Sent Events, or WebSockets — and how each handles reconnection and message ordering. Handshakes, headers, and trade-offs...
Scaling a Node.js Service
A single Node process runs your JavaScript on one event-loop thread — so scaling it is a system-design problem, not a config flag. Build intuition for statelessness as the...
Scaling WebSockets: Sticky Sessions, Fan-Out & Backpressure
Running real-time WebSockets across a fleet: why connections need sticky sessions, how a pub/sub backplane fans messages across nodes, tracking presence, per-connection...
Sociology of Queues: Waiting Lines as Social Systems
Thirty-eight questions about waiting lines as social systems: first-come-first-served as a social contract, single serpentine queues, perceived waiting time, priority queues,...
Server-Sent Events Deep Dive: The Event Stream Format
The precise SSE wire format from the WHATWG HTML spec: comment/keep-alive lines, multi-line data, the dispatch rule, named vs default events, the id and retry fields, stopping...
Systems-Level CS in the Browser: A Frontend Engineer's Guide to Reconciliation, the Event Loop, Race Conditions & Hashing
A 40-question deep dive built to help frontend engineers better understand algorithms by grounding classic computer-science ideas in browser behavior you can actually observe....