Vue 3 template references in composables

Question

I want to switch from the options API to the composition API and use composables instead of mixins. So far I've been using a global mixin with computed properties like this:

// globalMixin.js

 computed: {
    myAlert() {
        return this.$refs.myAlertDiv;
    }
 }

Then I used this mixin when creating the application:

// MyApp.js

const MyApp = {
   mixins: [globalMixin]
...
}

myAlert becomes a computed property of MyApp and I can use it without declaring it directly inside the MyApp property.

Now I want to achieve the same result using composables, let's say I have a component that imports composables:

// App.vue

<script setup>
import { useGlobalComposable} from './globalComposable.js';

const globalComposable = useGlobalComposable();

onMounted(() => {

// should work without declaring myAlert inside App.vue
console.log(globalComposable.myAlert);
})
...
</script>

May I? If so, how should I declare the myAlert template reference in the composable?

Answer 1

Your useGlobalComposable function should return myAlert like this:

const useGlobalComposable = function() { 
  
   const myAlertDiv = ....

   const myAlert = computed(() => {
        return myAlertDiv;
    });

   return {myAlert}
  }

You can then declare myAlert

in the settings block

const { myAlert } = useComposable();   
 return { myAlert }

Please note that this.$refs in mixin cannot be used directly with the Composition API. If you create a component, you can access component properties and methods using this.

This is an article about using refs with the Composition API.

Very simple working example using composable items in settings :

 const { ref, reactive, createApp } = Vue;
 
 const useComposable = function() { 
  const test = ref(1);
  return { test }; 
 }
 
 const App = { 
   setup() {    
      const { test } = useComposable();   
      return { test }
   }
}
 
 const app = createApp(App)
 app.mount('#app')

<div id="app">
  <div>Test: {{ test }}</div>
</div>
<script src="https://unpkg.com/vue@3/dist/vue.global.prod.js"></script>