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Practice modern frontend framework questions covering Vue 3, Svelte/SvelteKit, Solid.js, React Server Components, hydration vs resumability, islands architecture, and browser internals.
React still leads hiring volume by a large margin. Vue 3 is dominant in much of Asia and Europe and at companies like GitLab and Nuxt-based shops. Svelte / SvelteKit has grown fast and is the default at companies that prize small bundles. Solid.js and Qwik show up at performance-focused teams. Most interviews accept any framework you're fluent in - but knowing the architectural differences (signals vs VDOM, hydration vs resumability) is what separates senior candidates.
Hydration (React, Vue, classic SSR) re-runs the framework's setup code on the client to attach event handlers to server-rendered HTML - cost scales with app size. Resumability (Qwik) serializes interactivity into the HTML so there's no boot phase; handler code is downloaded only when actually triggered. Time-to-interactive becomes O(1) regardless of app size. Hydration is overwhelmingly more common in 2026 but resumability and partial hydration (islands) are pushing the model to be cheaper.
Fine-grained reactive primitives (signals) let frameworks update only the DOM nodes that read changed state - skipping virtual-DOM diffing and React's coarse 're-render the whole component' model. The performance wins for large trees with small per-frame updates are big enough that nearly every major framework converged on the pattern. There's even a TC39 proposal to add signals as a standard JS primitive shared across frameworks.
RSC moves data fetching and component rendering to the server. Server components ship zero JS to the browser, can hit a DB directly, and produce a serialized payload the client renders. The cost: server components can't use useState, useEffect, refs, or event handlers - those need a 'use client' boundary. The result is dramatically smaller bundles and simpler data-flow for content-heavy apps. Next.js App Router is the production home for RSC in 2026.
Yes - learning a second framework is the fastest way to internalize what's framework-specific vs universal. Vue's Composition API maps cleanly onto React hooks but with finer reactivity; Svelte teaches you what 'compile-time reactivity' looks like without VDOM. Most senior frontend interviews don't care which framework you bring; they want to know you understand state management, rendering models, accessibility, performance budgets, and the browser's actual behavior.
The render pipeline (style recalc -> layout -> paint -> composite, and which CSS properties skip layout/paint), the event loop and 16.7ms frame budget, the difference between transform/opacity (compositor-only) and width/top (forces layout), Web Vitals (LCP / INP / CLS), critical rendering path optimization (preload, fetchpriority), and DOM/CSSOM construction. At senior levels, also Service Workers, the History API, and how SPA navigation interacts with caches.