How to use computed properties in Vue
Łukasz Holeczek
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Creating efficient reactive calculations and data transformations is crucial for building performant Vue applications with complex business logic and dynamic user interfaces. As the creator of CoreUI, a widely used open-source UI library, I’ve implemented computed properties in numerous Vue components for filtering data, formatting displays, and calculating derived values in dashboards. From my expertise, the most powerful approach is to use computed properties which provide automatic caching and dependency tracking. This method ensures calculations only run when their dependencies change, optimizing performance compared to methods or watchers.
Use computed properties to create reactive calculations that automatically update when dependencies change.
<script setup>
import { ref, computed } from 'vue'
const firstName = ref('John')
const lastName = ref('Doe')
const fullName = computed(() => {
return firstName.value + ' ' + lastName.value
})
</script>
Computed properties are functions that return calculated values based on other reactive data. Vue automatically tracks which reactive properties the computed function accesses and only re-evaluates when those dependencies change. The computed value is cached until its dependencies change, making it more efficient than calling methods repeatedly. In templates, use computed properties like regular data properties without parentheses: {{ fullName }}.
Best Practice Note:
This is the same approach we use in CoreUI Vue components for data transformations and conditional rendering logic. Computed properties should be pure functions without side effects - use watchers instead for operations that need to trigger side effects or async operations.
