VueJS - Vue 3 Composition API: Custom Hooks

Creating Custom Hooks with the Composition API

The Composition API in Vue 3 allows you to create custom hooks, also known as composables, to encapsulate and reuse logic across components. This guide explores how to create and use custom hooks effectively in your Vue 3 applications.

Basic Example of a Custom Hook

Here is a basic example of a custom hook that manages a counter:

// useCounter.js
import { ref } from 'vue';

export function useCounter() {
  const count = ref(0);
  const increment = () => {
    count.value++;
  };
  const decrement = () => {
    count.value--;
  };

  return {
    count,
    increment,
    decrement
  };
}

// MyComponent.vue



                

Using Reactive State in Custom Hooks

Custom hooks can also use reactive state with the reactive function:

// useUser.js
import { reactive } from 'vue';

export function useUser() {
  const user = reactive({
    name: 'John Doe',
    age: 30
  });

  const updateUser = (newUser) => {
    user.name = newUser.name;
    user.age = newUser.age;
  };

  return {
    user,
    updateUser
  };
}

// UserComponent.vue



                

Using Computed Properties in Custom Hooks

Custom hooks can use computed properties to create derived state:

// useUser.js
import { reactive, computed } from 'vue';

export function useUser() {
  const user = reactive({
    firstName: 'John',
    lastName: 'Doe',
    age: 30
  });

  const fullName = computed(() => `${user.firstName} ${user.lastName}`);

  return {
    user,
    fullName
  };
}

// UserComponent.vue



                

Using Lifecycle Hooks in Custom Hooks

Custom hooks can also use lifecycle hooks to perform actions at specific stages of a component's lifecycle:

// useFetch.js
import { ref, onMounted, onUnmounted } from 'vue';

export function useFetch(url) {
  const data = ref(null);
  const error = ref(null);

  const fetchData = async () => {
    try {
      const response = await fetch(url);
      data.value = await response.json();
    } catch (err) {
      error.value = err;
    }
  };

  onMounted(fetchData);

  onUnmounted(() => {
    data.value = null;
    error.value = null;
  });

  return {
    data,
    error
  };
}

// DataComponent.vue



                

Best Practices

Follow these best practices when creating custom hooks with the Composition API:

• Encapsulate Reusable Logic: Use custom hooks to encapsulate logic that can be reused across multiple components.
• Keep Hooks Focused: Ensure that each custom hook has a single responsibility and avoids doing too much.
• Use Reactive Features: Leverage Vue's reactive features such as ref, reactive, computed, and lifecycle hooks to create powerful and flexible custom hooks.
• Document Your Hooks: Document your custom hooks to make it clear what they do and how to use them.
• Test Thoroughly: Test your custom hooks thoroughly to ensure they behave as expected in different scenarios.

Summary

This guide provided an overview of creating custom hooks with the Vue 3 Composition API. By leveraging custom hooks, you can promote code reuse and separation of concerns in your Vue 3 applications, making your codebase more maintainable and scalable.