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

How do you optimize performance in a Vue app?

Accepted Answer

**Target Audience:** Vue developers who have shipped an app and now need a method for making it faster. Assumes the Composition API basics. **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 number here was measured for this answer on Vue 3.5.44: the re-render counts by mounting the runnable example in jsdom with scripts/verify-vue-exa

Question 3

What are v-once and v-memo?

Accepted Answer

**Target Audience:** Vue developers optimising rendering, and anyone asked how Vue templates compile. **Difficulty:** Hard > **How to read this doc:** Plain language first, then 📌 Interview term: callouts. The compiled render functions below were printed by compile() from @vue/compiler-dom and @vue/compiler-ssr 3.5.44 (the import lines are trimmed); render counts and behaviour come from mounting the SFCs in jsdom with the repo verifier. For t

Question 4

What is Vapor mode in Vue 3.5+ and how does it differ from the virtual DOM?

Accepted Answer

**Target Audience:** Vue developers who know templates and reactivity and want to understand Vapor mode precisely, including its release status. No compiler background needed. **Difficulty:** Hard > **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. Vapor output in this doc was produced with **vue 3.6.0-rc.12**, a release candidate: compiled with its @vue/compiler-s

Question 5

When should you choose Vapor over VDOM in a real app — trade-offs?

Accepted Answer

**Target Audience:** Senior Vue developers and tech leads deciding whether and where to adopt Vapor mode. Assumes you know what Vapor is; if not, read [What is Vapor mode](/interview-question/what-is-vapor-mode-in-vue-3-5-and-how-does-it-differ-from-the-virtual-dom) first. **Difficulty:** Hard > **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 numbers here were meas

VUE.JSDECODED.

Easy

What are Vue directives? Give common examples.

Medium

How do you optimize performance in a Vue app?

Hard

What are v-once and v-memo?

What is Vapor mode in Vue 3.5+ and how does it differ from the virtual DOM?

When should you choose Vapor over VDOM in a real app — trade-offs?