Targeted.vue

<template>
  <div class="q-pa-md">
    <q-btn
      color="secondary"
      @click="toggle"
      :icon="$q.fullscreen.isActive ? 'fullscreen_exit' : 'fullscreen'"
      :label="$q.fullscreen.isActive ? 'Exit Fullscreen' : 'Go Fullscreen'"
    />
  </div>
</template>

<script>
import { useQuasar } from 'quasar'

export default {
  setup () {
    const $q = useQuasar()

    return {
      toggle (e) {
        const target = e.target.parentNode.parentNode.parentNode

        $q.fullscreen.toggle(target)
          .then(() => {
            // success!
          })
          .catch((err) => {
            alert(err)
            // uh, oh, error!!
            // console.error(err)
          })
      }
    }
  }
}
</script>