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agent-skills/skills/vue-best-practices/reference/refs-in-collections-need-value.md
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2026-02-16 16:27:42 -06:00

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---
title: Refs in Arrays and Collections Require .value
impact: MEDIUM
impactDescription: Refs inside reactive arrays, Maps, or Sets are NOT auto-unwrapped like in reactive objects
type: capability
tags: [vue3, reactivity, ref, arrays, collections, unwrapping]
---
# Refs in Arrays and Collections Require .value
**Impact: MEDIUM** - Unlike when a ref is a property of a reactive object, refs inside reactive arrays, Maps, and Sets are NOT automatically unwrapped. You must access them with `.value`, and forgetting this leads to silent bugs.
Vue only auto-unwraps refs when they are properties of reactive objects. When refs are elements in arrays or values in Maps/Sets, they remain as ref objects and require explicit `.value` access.
## Task Checklist
- [ ] Always use `.value` when accessing refs stored in reactive arrays
- [ ] Always use `.value` when accessing refs stored in reactive Maps or Sets
- [ ] Consider storing plain values instead of refs in collections to avoid confusion
- [ ] Be aware of this when iterating over arrays containing refs
**Incorrect:**
```javascript
import { ref, reactive } from 'vue'
const books = reactive([ref('Vue 3 Guide')])
const counts = reactive(new Map([['clicks', ref(0)]]))
// WRONG: Refs in arrays are NOT unwrapped
console.log(books[0]) // Ref object, not 'Vue 3 Guide'
books[0] = 'New Title' // Replaces the ref, doesn't update it!
// WRONG: Refs in Maps are NOT unwrapped
console.log(counts.get('clicks')) // Ref object, not 0
counts.get('clicks')++ // Does nothing useful
```
**Correct:**
```javascript
import { ref, reactive } from 'vue'
const books = reactive([ref('Vue 3 Guide')])
const counts = reactive(new Map([['clicks', ref(0)]]))
// CORRECT: Use .value for refs in arrays
console.log(books[0].value) // 'Vue 3 Guide'
books[0].value = 'New Title' // Updates the ref's value
// CORRECT: Use .value for refs in Maps
console.log(counts.get('clicks').value) // 0
counts.get('clicks').value++ // Increments to 1
```
```javascript
// ALTERNATIVE: Just store plain values in collections (simpler)
const books = reactive(['Vue 3 Guide', 'Vuex Handbook'])
const counts = reactive(new Map([['clicks', 0]]))
// No .value needed - but changes to individual items aren't independently reactive
console.log(books[0]) // 'Vue 3 Guide'
console.log(counts.get('clicks')) // 0
// Mutations still trigger reactivity through the reactive wrapper
books[0] = 'New Title' // Works
counts.set('clicks', counts.get('clicks') + 1) // Works
```
```vue
<template>
<!-- In templates, refs in arrays also need special handling -->
<div v-for="(book, index) in books" :key="index">
<!-- If book is a ref, you'd need: -->
{{ book.value }}
<!-- Or use computed to unwrap them first -->
</div>
</template>
```
## Reference
- [Vue.js Reactivity Fundamentals - Caveat in Arrays and Collections](https://vuejs.org/guide/essentials/reactivity-fundamentals.html#caveat-in-arrays-and-collections)