Computed Properties in Vue 3: A Comprehensive Guide

In Vue 3, computed properties are a powerful tool for building dynamic and reactive user interfaces. Computed properties allow you to define properties that are derived from other data properties, and are automatically updated whenever the data properties they depend on change. In this tutorial, we'll take a look at how to use computed properties in Vue 3 to build reactive and efficient UIs.

To define a computed property in Vue 3, you can use the computed option in the component's options object. The computed option is an object that contains the computed properties you want to define, and the corresponding getter and setter functions for each property.

For example, let's say you have a data property called firstName and a data property called lastName, and you want to define a computed property called fullName that combines the firstName and lastName properties:

    {{ fullName }}

export default {
  data() {
    return {
      firstName: 'Alice',
      lastName: 'Smith',
  computed: {
    fullName: {
      get() {
        return `${this.firstName} ${this.lastName}`;
      set(value) {
        const names = value.split(' ');
        this.firstName = names[0];
        this.lastName = names[1];

In this example, the fullName computed property is defined in the computed option, and the get function is used to return the combined value of the firstName and lastName properties. The set function is used to split the value of the fullName property into the firstName and lastName properties when it is set.

By using computed properties, you can build dynamic and reactive UIs that can adapt to changing data states and user input. For example, you can use computed properties to filter or sort lists, or to calculate values based on user input.

Whether you're building a simple form or a complex single-page application, computed properties are a key tool for building dynamic and reactive UIs with Vue 3. By learning how to use computed properties effectively, you can build responsive and interactive UIs that can adapt to changing data states and user input.