Nuxt/docs/6.bridge/3.bridge-composition-api.md

Legacy Composition API

Nuxt Bridge provides access to Composition API syntax. It is specifically designed to be aligned with Nuxt 3. Because of this, there are a few extra steps to take when enabling Nuxt Bridge, if you have been using the Composition API previously.

Remove Modules

• Remove @vue/composition-api from your dependencies.
• Remove @nuxtjs/composition-api from your dependencies (and from your modules in nuxt.config).

Using @vue/composition-api

If you have been using just @vue/composition-api and not @nuxtjs/composition-api, then things are very straightforward.

1. First, remove the plugin where you are manually registering the Composition API. Nuxt Bridge will handle this for you.

   - import Vue from 'vue'
   - import VueCompositionApi from '@vue/composition-api'
   -
   - Vue.use(VueCompositionApi)
   

2. Otherwise, there is nothing you need to do. However, if you want, you can remove your explicit imports from @vue/composition-api and rely on Nuxt Bridge auto-importing them for you.

Migrating from @nuxtjs/composition-api

Nuxt Bridge implements the Composition API slightly differently from @nuxtjs/composition-api and provides different composables (designed to be aligned with the composables that Nuxt 3 provides).

Because some composables have been removed and don't yet have a replacement, this will be a slightly more complicated process.

Remove @nuxtjs/composition-api/module from your buildModules

You don't have to immediately update your imports yet - Nuxt Bridge will automatically provide a 'shim' for most imports you currently have, to give you time to migrate to the new, Nuxt 3-compatible composables, with the following exceptions:

• withContext has been removed. See below.
• useStatic has been removed. There is no current replacement. Feel free to raise a discussion if you have a use case for this.
• reqRef and reqSsrRef, which were deprecated, have now been removed entirely. Follow the instructions below regarding ssrRef to replace this.

Set bridge.capi

import { defineNuxtConfig } from '@nuxt/bridge'

export default defineNuxtConfig({
  bridge: {
    capi: true
  }
})

For each other composable you are using from @nuxtjs/composition-api, follow the steps below.

useFetch

$fetchState and $fetch have been removed.

const {
- $fetch,
- $fetchState,
+ fetch,
+ fetchState,
} = useFetch(() => { posts.value = await $fetch('/api/posts') })

defineNuxtMiddleware

This was a type-helper stub function that is now removed.

Remove the defineNuxtMiddleware wrapper:

- import { defineNuxtMiddleware } from '@nuxtjs/composition-api`
- export default defineNuxtMiddleware((ctx) => {})
+ export default (ctx) => {}

For typescript support, you can use @nuxt/types:

import type { Middleware } from '@nuxt/types'

export default <Middleware> function (ctx) { }

defineNuxtPlugin

This was a type-helper stub function that is now removed.

You may also keep using Nuxt 2-style plugins, by removing the function (as with defineNuxtMiddleware).

Remove the defineNuxtPlugin wrapper:

- import { defineNuxtPlugin } from '@nuxtjs/composition-api'
- export default defineNuxtPlugin((ctx, inject) => {})
+ export default (ctx, inject) => {}

For typescript support, you can use @nuxt/types:

import type { Plugin } from '@nuxt/types'

export default <Plugin> function (ctx, inject) {}

useRouter and useRoute

Nuxt Bridge provides direct replacements for these composables via useRouter and useRoute.

The only key difference is that useRoute no longer returns a computed property.

- import { useRouter, useRoute } from '@nuxtjs/composition-api'

  const router = useRouter()
  const route = useRoute()

- console.log(route.value.path)
+ console.log(route.path)