Problem to use VueI18n outside a component

To use i18n with Vue 3’s composition API, but outside a component’s setup(), you can access its translation API (such as the t function) on its global property.

E. g. in a file with unit-testable composition functions:

// i18n/index.js

import { createI18n } from 'vue-i18n'
import en from './en.json'

  ...

export default createI18n({
  datetimeFormats: {en: {...}},
  locale: 'en',
  messages: { en }
})

// features/utils.js

//import { useI18n } from 'vue-i18n'
//const { t } = useI18n() // Uncaught SyntaxError: Must be called at the top of a `setup` function

import i18n from '../i18n'

const { t } = i18n.global