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62 lines
2.1 KiB
Markdown
62 lines
2.1 KiB
Markdown
---
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title: Always Use .value When Accessing ref() in JavaScript
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impact: HIGH
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impactDescription: Forgetting .value causes silent failures and bugs in reactive state updates
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type: capability
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tags: [vue3, reactivity, ref, composition-api]
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---
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# Always Use .value When Accessing ref() in JavaScript
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**Impact: HIGH** - Forgetting `.value` causes silent failures where state updates don't trigger reactivity, leading to hard-to-debug issues.
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When using `ref()` in Vue 3's Composition API, the reactive value is wrapped in an object and must be accessed via `.value` in JavaScript code. However, in templates, Vue automatically unwraps refs so `.value` is not needed there. This inconsistency is a common source of bugs.
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## Task Checklist
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- [ ] Always use `.value` when reading or writing ref values in `<script>` or `.js`/`.ts` files
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- [ ] Never use `.value` in `<template>` - Vue unwraps refs automatically there
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- [ ] When passing refs to functions, decide whether to pass the ref object or `.value`
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- [ ] Use IDE/TypeScript to catch missing `.value` errors early
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**Incorrect:**
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```javascript
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import { ref } from 'vue'
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const count = ref(0)
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// These do NOT work as expected
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count++ // Tries to increment the ref object, not the value
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count = 5 // Reassigns the variable, loses reactivity
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console.log(count) // Logs "[object Object]", not the number
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const items = ref([1, 2, 3])
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items.push(4) // Error: push is not a function
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```
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**Correct:**
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```javascript
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import { ref } from 'vue'
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const count = ref(0)
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// Always use .value in JavaScript
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count.value++ // Correctly increments to 1
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count.value = 5 // Correctly sets value to 5
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console.log(count.value) // Logs "5"
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const items = ref([1, 2, 3])
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items.value.push(4) // Correctly adds 4 to the array
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```
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```vue
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<template>
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<!-- In templates, NO .value needed - Vue unwraps automatically -->
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<p>{{ count }}</p>
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<button @click="count++">Increment</button>
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</template>
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```
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## Reference
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- [Vue.js Reactivity Fundamentals - ref()](https://vuejs.org/guide/essentials/reactivity-fundamentals.html#ref)
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