Vue 3 Composition API - How to get the component element ($el) on which component is mounted

Question

I want to use onMounted to initiate third-party library. To do that I need the component element as its context. In Vue 2 I would get it with this.$el but not sure how to do it with composition functions. setup has two arguments and none of them contains the element.

setup(props, context) {
    onMounted(() => {
        interact($el)
            .resizable();
    })
}

Solution 1

tl;dr:

In Vue 3, components are no longer limited at only 1 root element. Implicitly, this means you no longer have an $el.
You have to use ref to interact with any element in your template.

As pointed out by @AndrewSee in comments, when using a render function (not a template), you can specify the desired ref in createElement options:

render: function (createElement) {
  return createElement('div', { ref: 'root' })
}
// or, in short form:
render: h => h('div', { ref: 'root' })

---

initial answer:

As outlined in docs,

[...] the concepts of reactive refs and template refs are unified in Vue 3.

And you also have an example on how to ref a "root" element. Obviously, you don't need to name it root. Name it $el, if you prefer. However, doing so doesn't mean it will be available as this.$el, but as this.$refs.$el.

<template>
  <div ref="root"></div>
</template>

<script>
  import { ref, onMounted } from 'vue'

  export default {
    setup() {
      const root = ref(null)

      onMounted(() => {
        // the DOM element will be assigned to the ref after initial render
        console.log(root.value) // this is your $el
      })

      return {
        root
      }
    }
  }
</script>

In Vue 3 you're no longer limited to only one root element in <template>, so you have to specifically reference any element you want to interact with.

Solution 2

In Vue 3 + Composition API there is no $el alternative provided.

Even if you use Vue 3 with Options API, due to the availability of Fragments, it is recommended to use template refs for direct access to DOM nodes instead of relying on this.$el.

---

How to initiate a third-part-library

Let's say we have a div element for the third-part-library:

<template>
  Below we have a third-party-lib
  <div class="third-party-lib"></div>
</template>

And then we want to initiate it from the Javascript:

Solution 1 (recommended): Using template refs

<script setup>
import { ref, onMounted } from 'vue';

const $thirdPartyLib = ref(null); // template ref

onMounted(() => {
  $thirdPartyLib.value.innerText = 'Dynamically loaded';
});
</script>

<template>
  Below we have a third-party-lib
  <div ref="$thirdPartyLib" class="third-party-lib"></div>
</template>

Solution 2 (not recommended): Using non-documented @VnodeMounted

<script setup>
function initLib({ el }) {
  el.innerText = 'Dynamic content';
}
</script>

<template>
  Below we have a third-party-lib
  <div class="third-party-lib" @VnodeMounted="initLib"></div>
</template>

See both solutions live