Q: What is v-html and what is the risk of using it?

**Target Audience:** Beginners who have seen v-html in a codebase, or are tempted to use it. Basic HTML assumed; no security background needed. **Difficulty:** Easy > **How to read this doc:** Plain language first, then 📌 Interview term: callouts. The rendered HTML was produced by mounting the example on Vue 3.5.44 in jsdom and with renderToString . Because jsdom does not load images (so an onerror payload can never fire there), the attack its

Q: What is a Single File Component (SFC)?

**Target Audience:** Beginners who have seen .vue files but do not know what is inside one or what happens to it. Basic HTML, CSS and JavaScript assumed. **Difficulty:** Easy > **How to read this doc:** Plain language first, then 📌 Interview term: callouts. The compiled JavaScript and CSS in sections 5 and 6 are the real, unedited output of @vue/compiler-sfc 3.5.44, the same compiler @vitejs/plugin-vue calls during a Vite build. The runnable

Q: What is the difference between v-if and v-show?

**Target Audience:** Beginners who have used v-if or v-show and want to know which to pick. Basic HTML and CSS assumed. **Difficulty:** Easy > **How to read this doc:** Plain language first, then 📌 Interview term: callouts. Every DOM snapshot, lifecycle log and timing below was produced by mounting the code on Vue 3.5.44 in jsdom. The timings are jsdom numbers, useful for comparing the two directives with each other, not as real-browser figures. ## 1. Wh

Q: useAttrs() vs $attrs — how do you handle fallthrough attributes in composition API?

**Target Audience:** Vue developers moving to ` ` and the Composition API. Assumes you know what [fallthrough attributes ($attrs)](/interview-question/what-are-fallthrough-attributes-attrs) are; that sibling question covers the inheritance rules themselves. **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 "Verifi

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 is v-html and what is the risk of using it?

Accepted Answer

**Target Audience:** Beginners who have seen v-html in a codebase, or are tempted to use it. Basic HTML assumed; no security background needed. **Difficulty:** Easy > **How to read this doc:** Plain language first, then 📌 Interview term: callouts. The rendered HTML was produced by mounting the example on Vue 3.5.44 in jsdom and with renderToString. Because jsdom does not load images (so an onerror payload can never fire there), the attack its

Question 3

How do you bind classes and styles dynamically?

Accepted Answer

**Target Audience:** Anyone preparing for a Vue interview. Assumes basic HTML and CSS and a first look at Vue templates.
**Difficulty:** Easy

> **How to read this doc:** Plain language first, then `📌 Interview term:` callouts that give you the exact vocabulary. Every rendered class string, style attribute, warning and compiler line quoted below came from running the code on Vue 3.5.44 (compiled with `@vue/compiler-sfc`, mounted in jsdom).

## 1. Why This Even Matters — A Story First

Imagine a

Question 4

What are scoped styles in Vue?

Accepted Answer

**Target Audience:** Vue developers who write `<style scoped>` and want to know precisely what it does and where its edges are.
**Difficulty:** Easy

> **How to read this doc:** Plain language first, then `📌 Interview term:` callouts. The compiled CSS is real output from `@vue/compiler-sfc` 3.5.44 `compileStyle()` and from a `vite build` (vite 8.3.4, `@vitejs/plugin-vue` 6.0.10). The DOM attributes come from mounting the components in jsdom, and the computed colours were read from the built app

Question 5

What is a Single File Component (SFC)?

Accepted Answer

**Target Audience:** Beginners who have seen .vue files but do not know what is inside one or what happens to it. Basic HTML, CSS and JavaScript assumed. **Difficulty:** Easy > **How to read this doc:** Plain language first, then 📌 Interview term: callouts. The compiled JavaScript and CSS in sections 5 and 6 are the real, unedited output of @vue/compiler-sfc 3.5.44, the same compiler @vitejs/plugin-vue calls during a Vite build. The runnable

Question 6

What is the difference between v-if and v-show?

Accepted Answer

**Target Audience:** Beginners who have used v-if or v-show and want to know which to pick. Basic HTML and CSS assumed. **Difficulty:** Easy > **How to read this doc:** Plain language first, then 📌 Interview term: callouts. Every DOM snapshot, lifecycle log and timing below was produced by mounting the code on Vue 3.5.44 in jsdom. The timings are jsdom numbers, useful for comparing the two directives with each other, not as real-browser figures. ## 1. Wh

Question 7

How do Transition and TransitionGroup work?

Accepted Answer

**Target Audience:** Developers comfortable with Vue templates and basic CSS transitions who want to know exactly what Vue does during an animation. **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 class sequences in section 4 were recorded on Vue 3.5.44 in jsdom with the repo's verify-vue-example.mjs harness. jsdom runs no CSS

Question 8

What are fallthrough attributes ($attrs)?

Accepted Answer

**Target Audience:** Anyone preparing for a Vue interview. Assumes you know props and events. **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. All rendered HTML and warning text in the "Verified" sections was produced on Vue 3.5.44, with the repo verifier (compiled and mounted in jsdom) and with Vitest and Vue Test Utils. This doc covers the rul

Question 9

useAttrs() vs $attrs — how do you handle fallthrough attributes in composition API?

Accepted Answer

**Target Audience:** Vue developers moving to `

Question 10

What is the Composition API and how does it differ from the Options API?

Accepted Answer

**Target Audience:** Anyone preparing for a Vue interview — assumes basic JavaScript, no Vue experience required.
**Difficulty:** Medium

> **How to read this doc:** Plain language first, then `📌 Interview term:` callouts with the words an interviewer listens for. Every output quoted in a "Verified" section was produced by compiling the example with `@vue/compiler-sfc` and mounting it in jsdom on Vue 3.5.44, the current stable release; bundle sizes come from a real `vite build`.

## 1. Why This

VUE.JSDECODED.

Easy