Vue interviews focus on the reactivity system, the Composition API, and component communication. Below are the most common questions with model answers. Middle: deeper understanding, optimization, and real-world situations.
A function that uses Vue's reactivity and returns state and behaviour — useUser, usePagination. It beats a mixin because the source of every value is visible at the call site: with mixins two of them can define the same name and neither file tells you. Composables also compose, which is the whole point of the name.
Because reactivity lives in the proxy, and pulling a primitive out of it copies the value away from the proxy. The template then renders a number that never updates. toRefs fixes it by converting each property into a ref that keeps the link, which is also why returning toRefs(state) from a composable is the common shape.
A composable holding module-level state is a store in every meaningful way and is enough for most apps. Pinia earns its place when you need devtools, SSR-safe state, or plugins — and when several features write the same state and you want that traffic in one place. Provide and inject solves a different problem: passing down a tree without threading props.
A dependency that changes more often than the output does — an object recreated in the parent's render, or a computed reading more state than it uses. Vue's devtools highlight components as they update, which turns guessing into looking. v-memo exists for the rare case where the render itself is genuinely expensive.
SSR renders on each request, so content is current and the server does work per visitor. SSG renders at build time and serves static files, which is faster and cheaper but stale until the next build. The choice is per route rather than per app, and a marketing page and a dashboard rarely want the same one.
Render it and assert on what a user would see, using Testing Library or Vue Test Utils. Test behaviour — clicking this shows that — rather than internal state, because internal state is what refactoring changes. Mock the network at the request layer, not the component's own methods, or the test passes while the integration breaks.
In a real interview you speak under pressure. Cam asks these same questions, scores every answer, and shows exactly what to fix.
Practice a Middle Vue Frontend interview →