There are a couple of key points to remember when using the composition API.

There are a couple of points that you should be aware of when using @nuxtjs/composition-api.

'Keyed' functions

A number of helper functions use a key to pass JSON-encoded information from server to client (currently shallowSsrRef, ssrPromise, ssrRef and useAsync).

In order to make that possible, under the hood this library adds a key based on line number within your code.

If you want to use these functions within global composables, make sure to set a unique key based on each calling of the function - for example, you might key it to the route path. (Each function takes an optional second parameter that is this key.)

If you don't provide a unique key, this is the consequence:

function useMyFeature() {
  // Only one unique key is generated, no matter
  // how many times this function is called.
  const feature = ssrRef('')

  return feature

const a = useMyFeature()
const b = useMyFeature()

b.value = 'changed'
// On client-side, a's value will also be initialised to 'changed'

Here is how you might implement it by setting a key.

function useMyFeature(path: string) {
  const content = useAsync(
    () => fetch(`${path}`).then(r => r.json()),

  return {

export default useMyFeature

Shared server state

If you are declaring refs in the global state of your application - such as within plugins or in state/store files (for example, as a replacement for Vuex) - you should be aware that these refs are persisted across requests when your site is in production mode.

You should take especial care with declaring refs in this way.

Edit this page on GitHub Updated at Tue, Mar 2, 2021