Advanced interview questions in Vue, Angular & Svelte, page 2
Build a reactive data-fetching utility with Svelte stores
Tests store composition for async data fetching with caching and auto re-fetch. Strong answer: readable for lifecycle, derived's set callback for race-safe fetches, writable for private inputs. Red flag: exposed internals or missing cleanup.
What is the purpose of an Angular Resolve guard vs ngOnInit?
Tests routing lifecycle timing and UX state management. Strong answers: Resolve blocks activation until data returns; ngOnInit renders first then fetches, causing flicker.
Contrast SvelteKit file-system routing with Vue/Angular router configs
Contrast SvelteKit directory routes with Vue/Angular config routers; filesystem routing removes boilerplate but couples URLs to folders and limits dynamic registration.
How do you manage router scroll behavior and history position restoration?
Use scrollBehavior to return savedPosition on popstate and top: 0 on new navigations; handle hash anchors and async delays.
How would you design useCounter to support shared or independent state?
Tests your grasp of scope in Vue composables. Great answers contrast module-level refs for global singleton state against function-level refs for per-instance isolation, and explain tradeoffs.
When would you provide an Angular service at the component level?
Tests Angular DI scoping beyond singletons. A strong answer picks stateful reusable widgets, explains providers create one instance per subtree, and notes cleanup on destroy. Red flag: claiming this is for performance without mentioning state isolation.
Explain Svelte Action update and provide a reactive CSS example
Tests Svelte actions beyond initial mount. Strong answers explain update re-runs when parameters change, give a CSS custom properties example, and contrast with destroy. Red flag: suggesting the action re-runs from scratch or using reactive statements.
Zone.js and change detection optimization in Angular?
Zone.js wraps async (timers, events, HTTP), triggering change detection after each; use runOutsideAngular when external libraries fire high-frequency events.
How do you architect Svelte stores to minimize WebSocket re-renders?
Tests Svelte store granularity and subscription semantics. A great answer splits the monolith into domain stores, uses derived selectors to isolate slices, and leverages readable stores to encapsulate the WebSocket source.
How would you diagnose and optimize slow Angular component tests?
Tests Angular test economics and runner overhead. Strong answers profile with Vitest, swap Karma for jsdom/happy-dom, mock services, and reduce TestBed recompilation via targeted imports.
Testing shared Vue components: unit, a11y, visuals?
Unit tests (Vitest/Jest) for logic, accessibility tests (axe, Pa11y) for ARIA/keyboard, visual regression (Percy, Chromatic) for rendering.
How does Svelte compile count += 1 into DOM updates?
Tests if you know Svelte reactivity is compile-time via runes, not runtime proxies. Good answer: $state marks reactive vars; runes are compiler hooks; compiler emits DOM-sync code. Red flag: describing useState or VDOM.
Explain patch flags and static hoisting in Vue 3's compiler
Tests your grasp of compiler-informed virtual DOM optimizations. A strong answer covers patch flags as bitmap hints for dynamic bindings and static hoisting as extracting static nodes to skip diffing. Red flag: claiming Vue 3 removes the virtual DOM.
Compare SSR, SSG, and ISR trade-offs in meta-frameworks
What it tests: matching rendering modes to build time, freshness, and scale. Outline: contrast SSR per-request cost with SSG fast CDN delivery but stale content and long builds, then show ISR as lazy regeneration post-deploy.
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