Core Web Vitals: Make It Feel Fast
Practice diagnosing slow loading, delayed interactions, and shifting layouts. The scenarios cover LCP, INP, CLS, resource loading, hydration, web fonts, and differences between...
Quizzes
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CORS: Why Is the Browser Blocking Me?
Work through how browsers handle origins, CORS, preflights, credentials, opaque responses, SameSite cookies, CSP, CSRF, and the classic "but it works in Postman" trap.
Counterintuitive Probability
Monty Hall, the birthday paradox, the gambler's fallacy, and other places where careful probability overturns gut instinct. Each question pairs a tempting wrong answer with an...
CSS Cascade, Specificity & Inheritance
Read CSS conflicts the way the engine does: specificity by column, why @layer order outranks specificity (and how !important reverses it), unlayered-beats-layered, inherited...
The CSS Rendering Pipeline: Reflow vs Repaint & Why transform Is Cheap
Follow a pixel from CSS to screen: Style → Layout → Paint → Composite. See exactly what makes the browser re-run Layout (reflow) versus just Paint (repaint), why transform and...
CSS Stacking Contexts & z-index: Real Problems, Real Fixes
Why z-index: 9999 sometimes does nothing, what silently creates a stacking context, how the paint order actually works, and when isolation: isolate is the surgical fix. Every...
Data Structures Hiding in Your Codebase: A Field Guide for Frontend Engineers
Algorithms feel abstract until you spot them in the code you already ship. This quiz is for frontend engineers who want to understand algorithms by recognising the data...
What Your Database Actually Promises: Isolation & Consistency
CAP, isolation levels, and locking strategies as the documentation actually defines them. Covers why partition tolerance is never optional, what PostgreSQL's default Read...
Docker: What Actually Happens?
Test what Docker does with build contexts, caching, image layers, multi-stage builds, Unix signals, networking, storage, and Linux isolation. Each Question asks you to reason...
Economics of Small Decisions
Thirty questions on the economics hiding inside ordinary choices — not interest rates and GDP, but the trade-offs you make every day. Covers opportunity cost, the sunk cost...
English for Code Reviews
Practical English for pull requests and code reviews, organized as a small curriculum: commit subjects and PR titles, PR descriptions, the grammar that trips up non-native...
Everyday Physics Myths
Thirty-six everyday physics myths and half-truths — does a heavier object really fall faster, why is the sky blue, is there no gravity in space, and does the Coriolis effect...