Vue Demi (half in French) is a developing utility
allows you to write Universal Vue Libraries for Vue 2 & 3
See more details in this blog post
vue-demi should not be used for new projects and will be deprecated in the future.
Strategies
<=2.6: exports from vue + @vue/composition-api with plugin auto installing.2.7: exports from vue (Composition API is built-in in Vue 2.7).>=3.0: exports from vue, with polyfill of Vue 2’s set and del API.
Usage
Install this as your plugin’s dependency:
npm i vue-demi
# or
yarn add vue-demi
# or
pnpm i 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-rc.1",
"vue": "^2.0.0 || >=3.0.0"
},
"peerDependenciesMeta": {
"@vue/composition-api": {
"optional": true
}
},
"devDependencies": {
"vue": "^3.0.0" // or "^2.6.0" base on your preferred working environment
},
}
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!
When using with Vite, you will need to opt-out the pre-bundling to get vue-demi work properly by
export default defineConfig({
optimizeDeps: {
exclude: ['vue-demi']
}
})
Vue Demi provides extra APIs to help distinguish users’ environments and to do some version-specific logic.
isVue2 isVue3
import { isVue2, isVue3 } from 'vue-demi'
if (isVue2) {
// Vue 2 only
} else {
// Vue 3 only
}
Vue2
To avoid bringing in all the tree-shakable modules, we provide a Vue2 export to support access to Vue 2’s global API. (See #41.)
import { Vue2 } from 'vue-demi'
if (Vue2) {
Vue2.config.ignoredElements.push('x-foo')
}
install()
Composition API in Vue 2 is provided as a plugin and needs to be installed on the Vue instance before using. Normally, vue-demi will try to install it automatically. For some usages where you might need to ensure the plugin gets installed correctly, the install() API is exposed to as a safe version of Vue.use(CompositionAPI). install() in the Vue 3 environment will be an empty function (no-op).
import { install } from 'vue-demi'
install()
CLI
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
var Vue2 = undefined
export * from 'vue3'
export {
Vue,
Vue2,
isVue2,
isVue3,
}
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
Isomorphic Testings
You can support testing for both versions by adding npm alias in your dev dependencies. For example:
{
"scripts": {
"test:2": "vue-demi-switch 2 vue2 && jest",
"test:3": "vue-demi-switch 3 && jest",
},
"devDependencies": {
"vue": "^3.0.0",
"vue2": "npm:vue@2"
},
}
or
{
"scripts": {
"test:2": "vue-demi-switch 2 && jest",
"test:3": "vue-demi-switch 3 vue3 && jest",
},
"devDependencies": {
"vue": "^2.6.0",
"vue3": "npm:vue@3"
},
}
Examples
See examples.
Who is using this?
open a PR to add your library ;)
Underhood
See the blog post.
License
MIT License © 2020 Anthony Fu
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