Vue Computed Properties Deep Dive — Reactive Derivation

DodaTech Updated 2026-06-28 1 min read

In this tutorial, you will learn about Vue Computed Properties Deep Dive. We cover key concepts, practical examples, and best practices to help you master this topic.

Vue computed properties derive values from reactive data with automatic dependency tracking and Caching, recomputing only when dependencies change.

What You'll Learn

Computed vs method differences
Computed getter and setter
Dependency tracking
Computed performance optimization
Debugging computed

Why It Matters

Computed properties eliminate imperative code for derived data. Their cache prevents unnecessary recalculations, and automatic dependency tracking means you never manually list dependencies.

<template>
  <div>
    <input v-model.number="price" type="number" placeholder="Price" />
    <input v-model.number="taxRate" type="number" placeholder="Tax rate" step="0.01" />
    <p>Subtotal: ${{ subtotal }}</p>
    <p>Tax: ${{ tax.toFixed(2) }}</p>
    <p>Total: ${{ total.toFixed(2) }}</p>

    <h3>Full Name</h3>
    <input v-model="fullName" placeholder="Full name" />
    <p>First: {{ firstName }}, Last: {{ lastName }}</p>
  </div>
</template>

<script setup>
import { ref, computed } from "vue";

const price = ref(100);
const taxRate = ref(0.08);

const subtotal = computed(() => price.value);
const tax = computed(() => price.value * taxRate.value);
const total = computed(() => price.value + tax.value);

const firstName = ref("");
const lastName = ref("");

const fullName = computed({
  get: () => `${firstName.value} ${lastName.value}`.trim(),
  set: (val) => {
    const parts = val.split(" ");
    firstName.value = parts[0] || "";
    lastName.value = parts.slice(1).join(" ");
  },
});
</script>

Expected output: Price and tax inputs update derived computed values instantly. Full name input updates both firstName and lastName.

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