Easy everything in Vue, Angular & Svelte, page 2
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.
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 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.
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.
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.
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.
Bind an input to a variable and validate with reactivity
Tests Svelte reactivity: connecting DOM state to validation logic. Good answer: $state for the variable, $effect to run validation when it changes, cleanup if needed. Red flag: using effects where event handlers suffice or creating infinite loops.
Key differences between Template-Driven and Reactive Forms in Angular
This tests Angular form architecture tradeoffs. Contrast explicit synchronous reactive models with implicit asynchronous template-driven ones; assign reactive to scalable dynamic forms and template-driven to simple inputs.
How does Vue v-model work syntactically under the hood?
Tests if you know v-model is syntax sugar over prop and event pairs. Strong answers map text to :value/@input, checkboxes to :checked/@change, selects to value/@change, and note JS state wins. Red flag: calling it magic or true two-way binding.
How does Svelte scope component styles during compilation?
The compiler adds a unique attribute to component elements and rewrites selectors to target it, isolating styles.
What is Angular's default style encapsulation mechanism called?
Tests if you know Angular's default view encapsulation. A strong answer names ViewEncapsulation.Emulated, describes the unique attribute selector rewrite, and warns that global styles still pierce inward.
What attribute scopes styles to a Vue component?
This tests knowledge of Vue's style encapsulation. Add the scoped attribute to the style tag; Vue adds a unique data attribute to elements and selectors. A red flag is suggesting manual BEM or claiming scoped styles never affect child components.
How do you update Svelte arrays and objects to trigger reactivity?
This tests knowledge of Svelte 5 deep reactivity: $state wraps arrays in proxies so push and property mutations trigger updates. Mention $state first, then note legacy syntax needs reassignment. A red flag is claiming push never works in Svelte.
What is ngOnInit's purpose and why prefer it over the constructor?
Tests Angular lifecycle timing and input binding. Strong answer: ngOnInit runs once after inputs are initialized, but the constructor instantiates the class before bindings exist.
Vue 3 ref() vs reactive(): differences and when to use each
Tests Vue 3 Composition API reactivity primitives. Strong answer: ref() wraps any value in a .value wrapper and is the recommended default; reactive() returns a proxy accessed directly. Red flag: saying ref() is only for primitives or omitting .value entirely.
Explain two-way data binding and provide input binding syntax
Tests whether you see two-way binding as sugar for value binding plus an input event. Strong answer: show one syntax, then explain the prop-out, event-in pattern. Red flag: syntax only with no mention of change detection or unidirectional flow.
How do you conditionally render Login/Logout with isLoggedIn in Vue or Angular?
This tests DOM lifecycle awareness versus CSS toggling. A strong answer uses v-if/*ngIf for infrequent changes that need cleanup, and v-show/[hidden] for frequent toggles that should stay mounted. A red flag is treating them as interchangeable.
How do you emit events from a child to parent component?
This probes unidirectional data flow and child-to-parent event emission. In Vue, call $emit with a named event and payload; in Angular, use @Output with EventEmitter and emit the query. A red flag is suggesting two-way binding or direct parent mutation.
Primary mechanism for passing data from parent to child component
Tests unidirectional parent-to-child data flow and explicit component contracts. A strong answer names props or inputs, explains one-way binding, and warns against direct child mutation. Red flag: confusing props with global state or events.
Design the public API for a reusable Button component
Variant, size, disabled, type props; forward click; slots for content/icons; no router/form coupling.
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