vuepress2: how to get Vue instance so I can use third part vue plugin?

I am trying to use v-wave in VuePress 2 (the VuePress powered by Vue 3)

I followed the docs, try to use the v-wave as a local plugin of the VuePress 2

.vuepress/config.js

const vwave = require('path/to/v-wave.js');

module.exports = {
    plugins: [
        (options, app) => {
            app.use(vwave); // the `app` is a instance of VuePress not Vue
            return {name: 'v-wave'};
        }
    ]
};

But it didn't work, because the app isn't the Vue instance but the VuePress.

How can I install v-wave to make it work in VuePress 2?

Thanks a lot!

It seems there's no config API in VuePress specifically to configure the client app. However, the Plugin API supports configuring a root component in the client app with the clientAppRootComponentFiles property.

For example, this config points to .vuepress/RootComponent.vue:

// .vuepress/config.js
const path = require('path')

module.exports = {
  plugins: [
    {
      name: 'root-component-setup',
      clientAppRootComponentFiles: path.resolve(__dirname, './RootComponent.vue'),
    }
  ]
}

In that component file, use the Composition API's getCurrentInstance() to access the application instance's use() to globally install the v-wave plugin:

// .vuepress/RootComponent.vue
<template>
  <slot></slot>
</template>

<script>
import { getCurrentInstance, defineComponent } from 'vue'
import VWave from 'v-wave'

export default defineComponent({
  setup() {
    getCurrentInstance().appContext.app.use(VWave)
  }
})
</script>

demo