Q: What is async setup and top-level await?

**Target Audience:** Developers using <script setup> who want to load data with await and need to know what that changes. **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. The compiled output came from @vue/compiler-sfc 3.5.44's compileScript . The runtime traces came from a Vitest 5.0.5 test

Question 1

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 2

How do , and compose in Vue 3?

Accepted Answer

**Target Audience:** Developers who already know [Transition](/interview-question/how-do-transition-and-transitiongroup-work), [KeepAlive](/interview-question/what-is-keep-alive-in-vue) and [Suspense](/interview-question/what-is-suspense-in-vue) on their own and need them to work together. **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 tra

Question 3

How does <Suspense> work in Vue 3.5 after the 2024 stabilization?

Accepted Answer

**Target Audience:** Developers who already know what [Suspense](/interview-question/what-is-suspense-in-vue) is and need to predict how it behaves on later updates, with timeouts and with nested boundaries. **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 trace was produced on Vue 3.5.44 with the repo's verify-vue-example.mjs

Question 4

How do you fetch data in a Vue component (loading, errors, cancellation)?

Accepted Answer

**Target Audience:** Anyone preparing for a Vue interview who knows [watch and watchEffect](/interview-question/what-is-the-difference-between-watch-and-watcheffect) and basic fetch — no data-fetching library 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. All output was produced on Vue 3.5.44. **No real network was used*

Question 5

What is async setup and top-level await?

Accepted Answer

**Target Audience:** Developers using

Question 6

What is Suspense in Vue?

Accepted Answer

**Target Audience:** Developers who know components and promises and want to understand Vue's built-in way of coordinating async loading. **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. Every trace below was produced by compiling and mounting the code on Vue 3.5.44 in jsdom (or rendering it with --ssr) using the repo's verify-v

Question 7

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

Accepted Answer

**Target Audience:** Developers who split heavy components into separate chunks and need loading, error and retry behaviour they can rely on. **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. Every trace was produced on Vue 3.5.44, with the repo's verify-vue-example.mjs harness (SFC mounted in jsdom) or a Node script (server render plu

VUE.JSDECODED.

Easy

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

Medium

How do <Transition>, <KeepAlive> and <Suspense> compose in Vue 3?

How does <Suspense> work in Vue 3.5 after the 2024 stabilization?

How do you fetch data in a Vue component (loading, errors, cancellation)?

Hard

What is async setup and top-level await?

What is Suspense in Vue?

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