Vue Demi (half in French) is a developing utility allows you to write Universal Vue Libraries for Vue 2 & 3.


Install this as your plugin's dependency:

npm i vue-demi
# or
yarn add vue-demi

Add vue and @vue/composition-api to your plugin's peer dependencies to specify what versions you support.

  "dependencies": {
    "vue-demi": "latest"
  "peerDependencies": {
    "@vue/composition-api": "^1.0.0-beta.1",
    "vue": "^2.0.0 || >=3.0.0-rc.0"

Import everything related to Vue from it, it will redirect to vue@2 + @vue/composition-api or vue@3 based on users' environments.

import { ref, reactive, defineComponent } from 'vue-demi'

Publish your plugin and all is done!

Extra APIs

Vue Demi provides extra APIs to help distinguishing users' environments and to do some version-specific logics.

isVue2 isVue3

import { isVue2, isVue3 } from 'vue-demi'

if (isVue2) {
  // Vue 2 only
} else {
  // Vue 3 only


Composition API in Vue 2 is provided as a plugin and need to install to Vue instance before using. Normally, vue-demi will try to install it automatically. For some usages that you might need to ensure the plugin get installed correctly, the install() API is exposed to as a safe version of Vue.use(CompositionAPI). install() in Vue 3 environment will be an empty function (no-op).

import Vue from 'vue'
import { install } from 'vue-demi'



Manually Switch Versions

To explicitly switch the redirecting version, you can use these commands in your project's root.

npx vue-demi-switch 2
# or
npx vue-demi-switch 3

Package Aliasing

If you would like to import vue under an alias, you can use the following command

npx vue-demi-switch 2 vue2
# or
npx vue-demi-switch 3 vue3

Then vue-demi will redirect APIs from the alias name you specified, for example:

import * as Vue from 'vue3'

var isVue2 = false
var isVue3 = true

export * from 'vue3'
export {

Auto Fix

If the postinstall hook doesn't get triggered or you have updated the Vue version, try to run the following command to resolve the redirecting.

npx vue-demi-fix