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How do ref and reactive differ when defining reactive state in Vue's Composition API?
How do ref and reactive differ when defining reactive state in Vue's Composition API?
Jun 19, 2025 am 12:44 AM
In Vue 3 Composition API, ref is used to manage primitive types or responsive state that need to be maintained with variable references and accessed through .value; reactive is more suitable for objects that combine multiple responsive properties without .value. 1. ref supports reassignment and remains responsive, while reactive loses responsiveness after reassignment. 2. When used in a template, ref can be automatically unpacked, while reactive will lose its responsiveness after deconstruction and needs to be used with toRefs. 3. In terms of performance, reactive is more efficient for complex objects, but usually has little difference. Just choose according to your needs.
When working with Vue's Composition API, especially in Vue 3, you'll often come across ref and reactive for managing reactive state. While they both help track changes and update the UI accordingly, they're not interchangeable — each has its own use case and behavior.
Here's how they differ and when to choose one over the other.
1. Basic Usage and Value Types
-
refis best for:- Primitive values ??(
string,number,boolean) - When you need to keep a reference to a value that might change
- Keeping reactivity across function boundaries or loops
- Primitive values ??(
You access and modify it using .value :
const count = ref(0) count.value
-
reactiveworks well for:- Objects (including arrays and nested objects)
- Grouping related reactive data together in a single object
You use it directly without .value :
const state = reactive({ count: 0 })
state.count The main takeaway here is:
Use ref when dealing with primitives or needing a mutable reference. Use reactive when grouping multiple reactive properties into an object.
2. Reassignment Behavior Matters
This is a subtle but important difference.
If you have a ref , you can safely reassign it to another value and still retain reactivity:
let count = ref(0) count = ref(10) // Still reactive
But with reactive , if you reassign the variable, it loses reactive:
let state = reactive({ count: 0 })
state = reactive({ count: 10 }) // Reactivity lost on the new assignment So, if you plan to completely replace the value later, ref is safe.
3. Template Usage and Destructuring Gotchas
In templates, ref automatically unwraps, so you don't need .value . That makes them convenient:
<template>
<div>{{ count }}</div>
</template>
<script setup>
const count = ref(5)
</script> But if you destroy a reactive object, the destroyed variables lose reactive:
const state = reactive({ count: 0, name: 'Vue' })
const { count } = state // ? Not reactive anymore To fix this, you'd need to use toRefs :
const state = reactive({ count: 0, name: 'Vue' })
const { count } = toRefs(state) // ? Now count is a ref So, if you're planning to destroy your state, ref or toRefs are better choices.
4. Performance Considerations (Slight Edge)
Under the hood, reactive uses Proxy , while ref wraps the value in an object with a .value property. This means reactive may be slightly more performant for large, complex objects since it doesn't require wrapping every property in a ref.
However, unless you're dealing with very large datasets or performance-critical code, the difference is negligible.
So which should you use?
- Prefer
reffor primitives and when flexibility with reassignment matters. - Go with
reactivewhen grouping related state into an object and you don't need to destroy.
They both do similar jobs but behave differently in edge cases.
Basically that's it.
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