Question 1

What is Vue.js and what are its core features?

Accepted Answer

**Target Audience:** Complete beginners preparing for a first Vue interview. Assumes you know a little HTML and JavaScript, nothing about Vue or any other framework. **Difficulty:** Easy > **How to read this doc:** Every idea is explained in plain language first, then tagged with 📌 Interview term: so you also learn the exact words an interviewer listens for. The outputs in sections 5 and 6 were produced by actually compiling and running the code on Vue 3.5.44, the current stable r

Question 2

What changed from Vue 2 to Vue 3, and what does Vue 2 end of life mean?

Accepted Answer

**Target Audience:** Developers who meet Vue 2 code at work, or see Vue 2 tutorials online, and need to explain what is different in Vue 3. Basic Vue knowledge helps but every term is defined. **Difficulty:** Easy > **How to read this doc:** Plain language first, then 📌 Interview term: callouts. The comparisons in sections 4 and 5 were not taken from the migration guide: the same code was run on **vue 2.7.16** and **vue 3.5.44** side by side in Node with jsdom, and the outputs are

Question 3

How do you create a new Vue 3 app, and what is in the project structure?

Accepted Answer

**Target Audience:** Beginners who have never set up a frontend project. Assumes Node.js is installed and you can type commands in a terminal; no Vue, Vite or build-tool knowledge needed. **Difficulty:** Easy > **How to read this doc:** Plain language first, then 📌 Interview term: callouts with the vocabulary an interviewer expects. Nothing below is from memory: the project was generated by running create-vue 3.24.0 non-interactively in a sandbox, then installed, type-checked, bui

Question 4

Pinia colocation in 2025 — how do you colocate stores with routes/components?

Accepted Answer

**Target Audience:** Anyone preparing for a Vue interview who knows [what Pinia is](/interview-question/what-is-pinia-and-why-use-it) and has used lazy routes — mid-level and up. **Difficulty:** Medium > **How to read this doc:** Ideas are explained in plain language first, then tagged with 📌 Interview term: so you also learn the words an interviewer listens for. The chunk listings are real vite build output (Vite 8.3.4) of the small app whose files appear in the exam

Question 5

Why use storeToRefs with Pinia?

Accepted Answer

**Target Audience:** Anyone preparing for a Vue interview who has used [Pinia](/interview-question/what-is-pinia-and-why-use-it) at least once — basic ref and reactive knowledge assumed. **Difficulty:** Medium > **How to read this doc:** Ideas are explained in plain language first, then tagged with 📌 Interview term: so you also learn the words an interviewer listens for. Every output was produced on Vue 3.5.44 with pinia 4.1.0 (and 3.0.4 for one compariso

Question 6

What is a Vue plugin?

Accepted Answer

**Target Audience:** Vue developers who install libraries with `app.use()` and want to write their own.
**Difficulty:** Medium

> **How to read this doc:** Plain language first, then `📌 Interview term:` callouts. The plugin, the component that uses it and `main.js` were bundled with esbuild and run in jsdom on Vue 3.5.44; every log line and warning below is that run's real output. API availability was checked against the published `@vue/runtime-core` type definitions.

## 1. Why This Even Matte

Question 7

What are provide and inject?

Accepted Answer

**Target Audience:** Anyone preparing for a Vue interview. Assumes you know props and `ref()`. **Difficulty:** Medium > **How to read this doc:** Ideas are explained in plain language first, then tagged with 📌 Interview term: so you also learn the words an interviewer listens for. Every output in the "Verified" sections was produced on Vue 3.5.44: the runnable example with the repo verifier (compiled and mounted in jsdom), the app-level behaviour with a Node script against the sam

Question 8

How do Vue components communicate?

Accepted Answer

**Target Audience:** Anyone preparing for a Vue interview. Assumes basic JavaScript; no prior Vue knowledge needed. **Difficulty:** Medium > **How to read this doc:** Ideas are explained in plain language first, then tagged with 📌 Interview term: so you also learn the words an interviewer listens for. Every output quoted in the "Verified" sections was produced by running the code on Vue 3.5.44, either with the repo verifier (compiled with @vue/compiler-sfc and mounted

Question 9

How do you test Vue components (Vitest and Vue Test Utils)?

Accepted Answer

**Target Audience:** Anyone preparing for a Vue interview who can write [Single File Components](/interview-question/what-is-a-single-file-component-sfc) — no testing experience required. **Difficulty:** Medium > **How to read this doc:** Ideas are explained in plain language first, then tagged with 📌 Interview term: so you also learn the words an interviewer listens for. Every test in this doc was actually run: Vitest 5.0.5 with @vitejs/plugin-vue 6.0.10, @vue/test-utils 2.5.1, j

Question 10

What is Pinia and why use it?

Accepted Answer

**Target Audience:** Anyone preparing for a Vue interview who knows [ref and reactive](/interview-question/what-is-the-difference-between-ref-and-reactive) — no state-management library experience required. **Difficulty:** Medium > **How to read this doc:** Ideas are explained in plain language first, then tagged with 📌 Interview term: so you also learn the words an interviewer listens for. Every output below was produced on Vue 3.5.44 and pinia 4.1.0: Node scripts on create

VUE.JSDECODED.

Easy

What is Vue.js and what are its core features?

What changed from Vue 2 to Vue 3, and what does Vue 2 end of life mean?

How do you create a new Vue 3 app, and what is in the project structure?

Medium

Pinia colocation in 2025 — how do you colocate stores with routes/components?

Why use storeToRefs with Pinia?

What is a Vue plugin?

What are provide and inject?

How do Vue components communicate?

How do you test Vue components (Vitest and Vue Test Utils)?

What is Pinia and why use it?

What do toRef and toRefs do?

Hard

How would you structure state management for a large Vue app?

What is effectScope() and why do composables use it for cleanup?