Pre-order my new book on Vue Design Patterns at 30% discount. Click here for more details

Understanding Composables in Vue 3

Published by Solomon Eseme's profile picture Solomon Eseme on  Tue, 30 May 2023 15:30:00 GMT


In Vue 3, composables have emerged as a powerful and flexible way to encapsulate and reuse logic across components. Composables are functions or objects that contain reusable code that can be shared and composed together to enhance the functionality of your Vue applications. In this article, we will dive deep into the world of composables in Vue 3, understand their purpose and benefits, and explore examples to demonstrate how they can be leveraged effectively.

What are Composables?

Composables in Vue 3 are functions or objects that encapsulate a specific piece of functionality or logic. They are designed to be self-contained units that can be easily shared, reused, and composed together to build complex functionality in a declarative manner. Composables enable you to separate concerns and organize your codebase into smaller, more manageable units.

Benefits of Using Composables

Using composables in your Vue 3 applications brings several benefits:

  1. Reusability: Composables allow you to encapsulate and package specific logic, making it highly reusable across different components. This promotes code reuse and reduces duplication, leading to a more maintainable codebase.
  2. Modularity: By breaking down your code into smaller composables, you can achieve better modularity and separation of concerns. Each composable focuses on a specific task, making your codebase more organized and easier to understand.
  3. Testability: Composables can be easily tested in isolation since they encapsulate specific logic. This facilitates unit testing and improves the overall testability of your Vue applications.
  4. Composition: Composables are designed to be composable themselves. You can easily combine multiple composables together to create more complex functionality, providing a flexible way to build and extend features in your applications.

How to Use Composables in Vue 3

To start using composables in your Vue 3 applications, follow these steps:

1. Create a Composable

A composable can be created as a standalone function or an object that exports the necessary functions and reactive data. Here's an example of a simple composable called useCounter that provides counter functionality:

import { ref } from "vue";

export function useCounter() {
const count = ref(0);

function increment() {

function decrement() {

return { count, increment, decrement };

In this example, the useCounter composable returns an object with the count ref and two functions: increment and decrement.

2. Use the Composable in a Component

To use the composable in a component, import it and invoke the function. Here's an example of a component using the useCounter composable:

<p>Count: </p>
<button @click="increment">Increment
<button @click="decrement">Decrement

import { useCounter } from './useCounter';

export default {
setup() {
const { count, increment, decrement } = useCounter();

return { count, increment, decrement };

In this example, the component uses the useCounter composable and renders the count value and buttons to increment and decrement the count.

3. Compose Multiple Composables

Composables can be composed together to build more complex functionality. You can combine multiple composables by invoking them within the setup function of a component. Here's an example of composing the useCounter composable with another useTimer composable:

import { useCounter } from "./useCounter";
import { useTimer } from "./useTimer";

export default {
setup() {
const { count, increment, decrement } = useCounter();
const { time, start, stop } = useTimer();

return { count, increment, decrement, time, start, stop };

In this example, the component now has access to both the counter functionality from useCounter and the timer functionality from useTimer.

Learning and Exploring Composables

To deepen your knowledge of composables in Vue 3, consider the following resources:

These resources provide detailed explanations, examples, and best practices for working with composables in Vue 3. By studying them, you will gain a comprehensive understanding of how to leverage composables effectively in your Vue applications.


Composables in Vue 3 offer a powerful way to encapsulate and reuse logic across components. By creating modular and reusable units of code, you can enhance the maintainability, testability, and reusability of your Vue applications. Composables promote code organization, separation of concerns, and flexible composition of functionality.

In this article, we explored the concept of composables in Vue 3, discussed their benefits, and provided examples of how to use them in your applications. We also highlighted valuable learning resources to further expand your knowledge of composables in Vue 3.

Remember to refer to the official Vue 3 documentation and additional learning resources to deepen your understanding of composables and unlock their full potential in your Vue applications.


Architecting Vue.js 3 Enterprise-Ready Web Applications

Get the FREE chapter!

With this 15+ pages long chapter You will learn how to unit test a Vue.js 3 component and the components and pages’ methods: You will also learn Unit Testing tools such as Jest and Mocha and use them to effectively unit Test an enterprise project.

    Architecting Vue.js 3 Enterprise-Ready Web Applications chapter 9 Best Practice in Unit Testing