Question 1

How do defineProps and defineEmits work in <script setup>?

Accepted Answer

**Target Audience:** Vue 3 developers using `<script setup>` who want to understand the two macros they write in almost every component.
**Difficulty:** Easy

> **How to read this doc:** Plain language first, then `📌 Interview term:` callouts. All compiled output and compiler errors come from `@vue/compiler-sfc` 3.5.44 `compileScript()`; runtime logs from a two-component app compiled the same way and mounted in jsdom; type errors from `vue-tsc` 3.3.13.

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

Question 2

What do defineOptions() and defineSlots() do in <script setup>?

Accepted Answer

**Target Audience:** Vue developers using `<script setup>` who want the remaining component options and typed slots.
**Difficulty:** Medium

> **How to read this doc:** Plain language first, then `📌 Interview term:` callouts. The compiler output and every error message below come from running `@vue/compiler-sfc` 3.5.44; the runnable example was mounted in jsdom; the type errors come from `vue-tsc` 3.3.13. The version claims were checked against the published `@vue/runtime-core` type definitions

Question 3

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

Question 4

How do you use TypeScript with Vue (typed props, emits, refs, vue-tsc)?

Accepted Answer

**Target Audience:** Vue developers adopting TypeScript, or TypeScript developers new to Vue's single file components.
**Difficulty:** Medium

> **How to read this doc:** Plain language first, then `📌 Interview term:` callouts. Every type error below is real output from `vue-tsc` 3.3.13 with TypeScript 5.9 and `strict: true`; compiled output comes from `@vue/compiler-sfc` 3.5.44; runtime behaviour and warnings come from mounting the components in jsdom on Vue 3.5.44; the `vite build` result is

Question 5

How do generic <script setup> components work (generic="T")?

Accepted Answer

**Target Audience:** Vue and TypeScript developers who build reusable components such as lists, tables and selects.
**Difficulty:** Hard

> **How to read this doc:** Plain language first, then `📌 Interview term:` callouts. All type errors below are real output from `vue-tsc` 3.3.13 (TypeScript 5.9, `strict: true`) run on the example files; the compiled output comes from `@vue/compiler-sfc` 3.5.44; the runnable example was mounted in jsdom on Vue 3.5.44.

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

VUE.JSDECODED.

Easy

How do defineProps and defineEmits work in <script setup>?

Medium

What do defineOptions() and defineSlots() do in <script setup>?

How do you make provide/inject type-safe?

How do you use TypeScript with Vue (typed props, emits, refs, vue-tsc)?

Hard

How do generic <script setup> components work (generic="T")?