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 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 are dynamic arguments and v-bind shorthand?

Accepted Answer

**Target Audience:** Vue beginners who know what `v-bind` and `v-on` do and want the full picture of their syntax.
**Difficulty:** Easy

> **How to read this doc:** Plain language first, then `📌 Interview term:` callouts. The compiled code, compiler errors, runtime errors and DOM output below came from running Vue 3.5.44 (`@vue/compiler-dom` for compiler output, jsdom for the runtime).

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

Think of a label maker at a warehouse. Normally the operator typ

Question 3

How do you render lists with v-for?

Accepted Answer

**Target Audience:** Beginners who need to show a list of things (products, messages, todos) in a Vue component. Basic JavaScript arrays and objects assumed. **Difficulty:** Easy > **How to read this doc:** Plain language first, then 📌 Interview term: callouts. Every rendered list, DOM-identity check and error message below came from mounting the code on Vue 3.5.44 in jsdom and clicking through it. ## 1. Why This Even Matters — A Story First Imagine you are writing place cards f

Question 4

How does v-model work on form inputs?

Accepted Answer

**Target Audience:** Vue beginners building their first forms. Assumes HTML form elements and a little JavaScript.
**Difficulty:** Easy

> **How to read this doc:** Plain language first, then `📌 Interview term:` callouts. Every state dump, compiler snippet and compiler error below came from running Vue 3.5.44: templates compiled with `@vue/compiler-sfc` / `@vue/compiler-dom`, mounted in jsdom, with a driver typing, clicking and selecting.

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

Picture a

Question 5

What is Vue template syntax (interpolation, directives, expressions)?

Accepted Answer

**Target Audience:** Beginners who know basic HTML and JavaScript and are reading Vue templates for the first time. **Difficulty:** Easy > **How to read this doc:** Plain language first, then 📌 Interview term: callouts with the precise vocabulary. Every rendered output, compiled render function, warning and error message below was produced by running the code on Vue 3.5.44 (@vue/compiler-dom for compiler output, the repo verifier for mounted components). ## 1. Why Th

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

What is the difference between watch and watchEffect?

Accepted Answer

**Target Audience:** Vue developers who reach for watchers and want to choose between the two on purpose rather than by habit. **Difficulty:** Medium > **How to read this doc:** Plain language first, then 📌 Interview term: callouts with the vocabulary interviewers listen for. Every output below was produced on Vue 3.5.44, with node for the reactivity probe and with @vue/compiler-sfc plus jsdom for the components. This page is about the *tracking model*; t

Question 8

What is the difference between ref and reactive?

Accepted Answer

**Target Audience:** Developers who have written a Vue 3 component or two and want to stop guessing between ref and reactive. **Difficulty:** Medium > **How to read this doc:** Plain language first, then 📌 Interview term: callouts with the vocabulary interviewers expect. Every output below was produced on Vue 3.5.44: the reactivity probe with node, the component by compiling it with @vue/compiler-sfc and clicking through it in js

Question 9

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 10

How do you make provide/inject type-safe?

Accepted Answer

**Target Audience:** Vue developers using TypeScript. Assumes you know what [provide and inject](/interview-question/what-are-provide-and-inject) do; this doc is only about typing them. **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 type errors quoted here are the real output of vue-tsc 3.3.13 on Vue 3.5.44, and the runtime ou

VUE.JSDECODED.

Easy

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

What are dynamic arguments and v-bind shorthand?

How do you render lists with v-for?

How does v-model work on form inputs?

What is Vue template syntax (interpolation, directives, expressions)?

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

Medium

What is the difference between watch and watchEffect?

What is the difference between ref and reactive?

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

How do you make provide/inject type-safe?

Why use storeToRefs with Pinia?

How do dynamic routes and route params work in Vue Router?

What is a Vue plugin?

What are provide and inject?

Hard

How does defineAsyncComponent work with loading, error and retry in 2025?

What do markRaw and toRaw do?

How does Vue's virtual DOM diff keyed lists?

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

What are shallowRef and shallowReactive?

When should you use shallowRef / shallowReactive / triggerRef?

What are common reactivity caveats in Vue?

What is a custom renderer in Vue (createRenderer)?