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

Question 1

What are Vue directives? Give common examples.

Accepted Answer

**Target Audience:** Beginners who can read a basic Vue template and want to understand every v- attribute they see. Basic HTML and JavaScript assumed. **Difficulty:** Easy > **How to read this doc:** Plain language first, then 📌 Interview term: callouts. The rendered output, the compiled render function and the warnings below come from compiling and mounting the example on Vue 3.5.44, not from memory. ## 1. Why This Even Matters — A Story First Imagine a theatre sc

Question 2

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 3

How do you handle errors in Vue (onErrorCaptured, app.config.errorHandler)?

Accepted Answer

**Target Audience:** Anyone preparing for a Vue interview who knows [the component lifecycle](/interview-question/what-are-vue-lifecycle-hooks) — no error-monitoring 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 was produced on Vue 3.5.44: the propagation scripts ran in Node with jsdom, once in development an

Question 4

Why are composables preferred over mixins?

Accepted Answer

**Target Audience:** Vue developers maintaining Options API code or moving a codebase to the Composition API.
**Difficulty:** Medium

> **How to read this doc:** Plain language first, then `📌 Interview term:` callouts. Every behaviour claimed here, including the absence of warnings, was observed by compiling and mounting the two examples on Vue 3.5.44 with the repo verifier.

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

Picture a shared office whiteboard. Team A writes "count: 3" on it, meaning

Question 5

How do you create a custom directive in Vue?

Accepted Answer

**Target Audience:** Vue developers who need low-level DOM behaviour they can reuse across templates. **Difficulty:** Medium > **How to read this doc:** Plain language first, then 📌 Interview term: callouts. Every log line and warning below was printed on Vue 3.5.44 by mounting the SFCs in jsdom with the repo verifier (dev build), and the SSR output by renderToString from @vue/server-renderer. The typed example was checked with TypeScript 5 in strict mode

Question 6

What are composables in Vue?

Accepted Answer

**Target Audience:** Vue developers who know `ref` and `computed` and want to reuse logic properly.
**Difficulty:** Medium

> **How to read this doc:** Plain language first, then `📌 Interview term:` callouts. Every output in the "Verified" sections was produced by running the examples on Vue 3.5.44: the SFC was compiled and mounted in jsdom with the repo verifier, the plain-JavaScript example ran under Node.

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

Think of a power tool battery. You do not

Question 7

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

Question 8

What are Vue lifecycle hooks?

Accepted Answer

**Target Audience:** Vue developers who can write a component and want to know exactly when their code runs.
**Difficulty:** Medium

> **How to read this doc:** Plain language first, then `📌 Interview term:` callouts. Every ordering in this doc was printed by `console.log` calls in real components, compiled and mounted in jsdom (or rendered with `renderToString`) on Vue 3.5.44. Nothing about order is quoted from memory.

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

Think about opening a shop fo

VUE.JSDECODED.

Easy

What are Vue directives? Give common examples.

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

Medium

How do you handle errors in Vue (onErrorCaptured, app.config.errorHandler)?

Why are composables preferred over mixins?

How do you create a custom directive in Vue?

What are composables in Vue?

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

What are Vue lifecycle hooks?