Q: Can a computed property be writable?

**Target Audience:** Vue developers who know read-only computed and want to know when a writable one is the right tool. **Difficulty:** Medium > **How to read this doc:** Plain language first, then 📌 Interview term: callouts with the vocabulary an interviewer expects. All output below was produced on Vue 3.5.44: the probe with node , the type errors with TypeScript 5 against Vue's own typings, and the component by compiling it with @vue/compiler-sfc<

Question 1

What is defineModel() in Vue 3.4+ and how does it replace manual prop + emit?

Accepted Answer

**Target Audience:** Vue 3 developers who know the [component v-model contract](/interview-question/how-does-v-model-work-on-components) and want to know what `defineModel()` really does.
**Difficulty:** Medium

> **How to read this doc:** Plain language first, then `📌 Interview term:` callouts. The compiled output is from `@vue/compiler-sfc` 3.5.44 `compileScript()`, and every value read after a click or keystroke came from mounting the components in jsdom on Vue 3.5.44. Version history comes

Question 2

How does v-model work on components?

Accepted Answer

**Target Audience:** Vue developers who use `v-model` on inputs and now need their own components to support it.
**Difficulty:** Medium

> **How to read this doc:** Plain language first, then `📌 Interview term:` callouts. The compiled output, warnings, compiler errors and the state after typing that are quoted below all came from Vue 3.5.44, compiled with `@vue/compiler-dom` and `@vue/compiler-sfc` and mounted in jsdom.

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

A hotel guest wants a differe

Question 3

Can a computed property be writable?

Accepted Answer

**Target Audience:** Vue developers who know read-only computed and want to know when a writable one is the right tool. **Difficulty:** Medium > **How to read this doc:** Plain language first, then 📌 Interview term: callouts with the vocabulary an interviewer expects. All output below was produced on Vue 3.5.44: the probe with node, the type errors with TypeScript 5 against Vue's own typings, and the component by compiling it with @vue/compiler-sfc<

VUE.JSDECODED.

Medium

What is defineModel() in Vue 3.4+ and how does it replace manual prop + emit?

How does v-model work on components?

Can a computed property be writable?