Vue.js is a popular JavaScript framework used for building user interfaces. One of the key features of Vue.js is its computed properties, which allow you to react to data being updated and using the value in your template. In this article, we will explore what computed properties are, how they work, and how to use them in your Vue.js applications.

What are Computed Properties?

Computed properties are functions that are defined on a Vue instance and return a value based on other data in the instance. They are similar to methods in that they can perform calculations and return a value, but they are different in that they are cached based on their dependencies. This means that if the data they depend on changes, the computed property will be updated automatically. Vue will keep track of all changes done to computed properties and will handle the rest.

How do Computed Properties Work?

Computed properties are defined using the computed property on a Vue instance. Here is an example:

    <input v-model="message">
    {{ message }} : {{ counter }}

new Vue({
  data: {
    message: 'I\'m testing Vue.js!'
  computed: {
    counter: function () {
      return this.message.trim().length;

In this example, we define a computed property called counter that returns the message length data property’s character length. Whenever the message property changes, the counter the property will be updated automatically and therefore show up on the template, enabling a more reactive interactive experience for the end user.

When to Use Computed Properties?

Computed properties are useful when you need to perform calculations based on other data in your Vue instance. They are particularly useful when you need to perform the same calculation multiple times, as they are cached and will not be recalculated unnecessarily.

Here are some examples of when you might use computed properties:

  • Formatting data for display
  • Filtering data based on user input
  • Sorting data based on user input
  • Calculating totals or averages
  • Counters


Computed properties are a powerful feature of Vue.js that allows you to define values based on other data in your Vue instance. They are useful for performing calculations and formatting data for display. If you are new to Vue.js, try to take some time to explore computed properties and see how they can improve your applications.

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