Easy interview questions in Vue, Angular & Svelte, page 2
What is prop drilling and when is it a problem?
Define it as passing data through components that ignore it; move to global state when unrelated branches need same data.
Share state between sibling components without a state library
Tests if you over-engineer simple sibling state. Good answers lift state to the common parent, passing data down via props and changes up via events; or use built-in primitives like Svelte stores or an Angular shared service.
Fetch data on first render and manage loading and error states
Tests lifecycle awareness and separation of concerns. Strong answer: use mount hook (onMounted, ngOnInit, onMount), hold reactive data/loading/error states, and render conditional UI branches. Red flag: calling fetch directly in template or render function.
How do you define a basic Vue or Angular route?
Tests SPA routing conventions. Angular: Routes array in app.routes.ts with path and component, provided in bootstrap. Vue: routes array in src/router/index.js passed to createRouter. Red flag: omitting the outlet or placing config in a component.
Create a template link to a route without a full page reload
Tests SPA client-side routing knowledge. Strong answer: name RouterLink or routerLink, explain click interception and History API URL updates, and contrast with plain anchor tags.
How do you implement a data-fetching Composable in Vue 3?
Write useFetch accepting a URL, exposing data, loading, and error refs, then return them.
How to create a singleton Angular auth service
Tests Angular dependency injection and singleton scope. Strong answer: use the Injectable decorator with providedIn set to root for an application-wide singleton, then inject it into components.
What is a Svelte Action? Write a simple logging action.
Define a function receiving the node, log a message, and optionally return destroy.
Vue computed vs method: performance difference and when to choose each?
This tests Vue reactivity caching. Answer: computed caches and reruns only when reactive deps change, while methods run each render. Choose computed for derived data; methods for events/args. Red flag: saying computed is always faster or passing arguments.
How do you lazy-load a route in Vue or Angular?
Tests route-level code splitting. Strong answers mention dynamic imports in Vue Router or Angular loadChildren and highlight a smaller initial JS bundle. Red flag: confusing this with image lazy loading or claiming it speeds up runtime navigation.
What is the fundamental difference between unit and component tests?
Isolation levels in frontend testing. Unit tests verify single functions or composables with mocked dependencies; component tests verify mounting, rendering, and interaction and pull in more code.
What is Angular's TestBed and when would you use it?
Say createComponent returns a fixture with no immediate binding, so await fixture.whenStable before asserting DOM.
What is the Virtual DOM's role during a Vue state update?
Tests your grasp of Vue's reactive render pipeline. A strong answer: state change triggers a new virtual DOM tree; runtime diffs it against the old tree to apply only necessary real DOM updates. Red flag: saying virtual DOM updates browser DOM directly.
What is SSR and what are its advantages over a client-side SPA?
This tests server-client rendering trade-offs. A strong answer defines SSR as server HTML generation plus client hydration, citing faster time-to-content, better SEO for async data, and unified component logic.
What is the purpose of +page.server.js in SvelteKit?
Exclusively server-side load feeding the data prop, used for secrets like DB queries and private env vars.
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