v3.16
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defineNuxtComponent

Source
defineNuxtComponent() is a helper function for defining type safe components with Options API.
defineNuxtComponent() is a helper function for defining type safe Vue components using options API similar to defineComponent(). defineNuxtComponent() wrapper also adds support for asyncData and head component options.
Using <script setup lang="ts"> is the recommended way of declaring Vue components in Nuxt 3.
Read more in Docs > Getting Started > Data Fetching.

asyncData()

If you choose not to use setup() in your app, you can use the asyncData() method within your component definition:

pages/index.vue
<script lang="ts">
export default defineNuxtComponent({
  async asyncData() {
    return {
      data: {
        greetings: 'hello world!'
      }
    }
  },
})
</script>

head()

If you choose not to use setup() in your app, you can use the head() method within your component definition:

pages/index.vue
<script lang="ts">
export default defineNuxtComponent({
  head(nuxtApp) {
    return {
      title: 'My site'
    }
  },
})
</script>