vuepress/lib/app/dataMixin.js

import Vue from 'vue'
import { siteData } from './.temp/siteData'
import { findPageForPath } from './util'

function prepare (siteData) {
  siteData.pages.forEach(page => {
    if (!page.frontmatter) {
      page.frontmatter = {}
    }
  })
  Object.freeze(siteData)
}

prepare(siteData)
const store = new Vue({
  data: { siteData }
})

if (module.hot) {
  module.hot.accept('./.temp/siteData', () => {
    prepare(siteData)
    store.siteData = siteData
  })
}

export default {
  computed: {
    $site () {
      return store.siteData
    },
    $page () {
      return findPageForPath(
        this.$site.pages,
        this.$route.path
      )
    }
  }
}