Master JavaScript Promise & Async Execution
Step through the event loop, microtask & macrotask queues, async/await suspension, and tricky async patterns. Detailed MDN-linked explanations reveal after every answer.
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Message Delivery: Guarantees, Ordering & Idempotency
At-most-once vs at-least-once vs "exactly-once," why duplicates and gaps happen, and how idempotency, dedup, sequence numbers, and per-key ordering tame them. The...
Node.js Buffers & Binary Data
How Buffer, Uint8Array, ArrayBuffer, and DataView fit together; UTF-8 / hex / base64 encodings; byte order; which operations share memory versus copy; and why turning binary...
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...
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),...
PostgreSQL Performance: Read the Query Plan
Thirty questions about diagnosing PostgreSQL performance from real EXPLAIN ANALYZE output. Covers index design, sequential scans, cardinality estimates, composite-index order,...
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...
RAG Without the Hand-Waving
A practical quiz about how RAG systems split, retrieve, rank, cite, and evaluate information, and how they fail. Every explanation links to supporting research or technical...
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...
React: When Does This Re-render?
Thirty-two code-driven questions about render snapshots, Effect synchronization, identity, memoization, refs, React 19 Server and Client Components, use(), and Suspense. Assume...
Read the Git Graph: Commits, Parents & What Rewriting Really Does
Git is a graph, not a timeline. Almost every confusing thing it does makes sense the moment you can see the parent pointers. This quiz gives you the graph before a command and...