Layout.vue

<template>
  <div class="theme-container"
    :class="pageClasses"
    @touchstart="onTouchStart"
    @touchend="onTouchEnd">
    <Navbar v-if="shouldShowNavbar" @toggle-sidebar="toggleSidebar"/>
    <div class="sidebar-mask" @click="toggleSidebar(false)"></div>
    <Sidebar :items="sidebarItems" @toggle-sidebar="toggleSidebar">
      <slot name="sidebar-top" slot="top"/>
      <slot name="sidebar-bottom" slot="bottom"/>
    </Sidebar>
    <div class="custom-layout" v-if="$page.frontmatter.layout">
      <component :is="$page.frontmatter.layout"/>
    </div>
    <Home v-else-if="$page.frontmatter.home"/>
    <Page v-else :sidebar-items="sidebarItems">
      <slot name="page-top" slot="top"/>
      <slot name="page-bottom" slot="bottom"/>
    </Page>
  </div>
</template>

<script>
import Vue from 'vue'
import nprogress from 'nprogress'
import Home from './Home.vue'
import Navbar from './Navbar.vue'
import Page from './Page.vue'
import Sidebar from './Sidebar.vue'
import { pathToComponentName } from '@app/util'
import { resolveSidebarItems } from './util'
import throttle from 'lodash/throttle'

export default {
  components: { Home, Page, Sidebar, Navbar },
  data () {
    return {
      isSidebarOpen: false
    }
  },

  computed: {
    shouldShowNavbar () {
      const { themeConfig } = this.$site
      const { frontmatter } = this.$page
      if (
        frontmatter.navbar === false ||
        themeConfig.navbar === false) {
        return false
      }
      return (
        this.$title ||
        themeConfig.logo ||
        themeConfig.repo ||
        themeConfig.nav ||
        this.$themeLocaleConfig.nav
      )
    },
    shouldShowSidebar () {
      const { frontmatter } = this.$page
      return (
        !frontmatter.layout &&
        !frontmatter.home &&
        frontmatter.sidebar !== false &&
        this.sidebarItems.length
      )
    },
    sidebarItems () {
      return resolveSidebarItems(
        this.$page,
        this.$route,
        this.$site,
        this.$localePath
      )
    },
    pageClasses () {
      const userPageClass = this.$page.frontmatter.pageClass
      return [
        {
          'no-navbar': !this.shouldShowNavbar,
          'sidebar-open': this.isSidebarOpen,
          'no-sidebar': !this.shouldShowSidebar
        },
        userPageClass
      ]
    }
  },

  created () {
    if (this.$ssrContext) {
      this.$ssrContext.title = this.$title
      this.$ssrContext.lang = this.$lang
      this.$ssrContext.description = this.$page.description || this.$description
    }
  },

  mounted () {
    // update title / meta tags
    this.currentMetaTags = []
    const updateMeta = () => {
      document.title = this.$title
      document.documentElement.lang = this.$lang
      const meta = [
        {
          name: 'description',
          content: this.$description
        },
        ...(this.$page.frontmatter.meta || [])
      ]
      this.currentMetaTags = updateMetaTags(meta, this.currentMetaTags)
    }
    this.$watch('$page', updateMeta)
    updateMeta()

    window.addEventListener('scroll', this.onScroll)

    // configure progress bar
    nprogress.configure({ showSpinner: false })

    this.$router.beforeEach((to, from, next) => {
      if (to.path !== from.path && !Vue.component(pathToComponentName(to.path))) {
        nprogress.start()
      }
      next()
    })

    this.$router.afterEach(() => {
      nprogress.done()
      this.isSidebarOpen = false
    })
  },

  beforeDestroy () {
    updateMetaTags(null, this.currentMetaTags)

    window.removeEventListener('scroll', this.onScroll)
  },

  methods: {
    toggleSidebar (to) {
      this.isSidebarOpen = typeof to === 'boolean' ? to : !this.isSidebarOpen
    },
    // side swipe
    onTouchStart (e) {
      this.touchStart = {
        x: e.changedTouches[0].clientX,
        y: e.changedTouches[0].clientY
      }
    },
    onTouchEnd (e) {
      const dx = e.changedTouches[0].clientX - this.touchStart.x
      const dy = e.changedTouches[0].clientY - this.touchStart.y
      if (Math.abs(dx) > Math.abs(dy) && Math.abs(dx) > 40) {
        if (dx > 0 && this.touchStart.x <= 80) {
          this.toggleSidebar(true)
        } else {
          this.toggleSidebar(false)
        }
      }
    },
    onScroll: throttle(() => {
      setActiveHash()
    }, 200)
  }
}

function updateMetaTags (meta, current) {
  if (current) {
    current.forEach(c => {
      document.head.removeChild(c)
    })
  }
  if (meta) {
    return meta.map(m => {
      const tag = document.createElement('meta')
      Object.keys(m).forEach(key => {
        tag.setAttribute(key, m[key])
      })
      document.head.appendChild(tag)
      return tag
    })
  }
}

function setActiveHash () {
  const anchors = gatherHeaderAnchors()

  const scrollTop = Math.max(window.pageYOffset, document.documentElement.scrollTop, document.body.scrollTop)

  for (let i = 0; i < anchors.length; i++) {
    const anchor = anchors[i]
    const nextAnchor = anchors[i + 1]

    const isActive = i === 0 && scrollTop === 0 ||
      (scrollTop >= anchor.parentElement.offsetTop + 10 &&
        (typeof nextAnchor === 'undefined' || scrollTop < nextAnchor.parentElement.offsetTop - 10))

    if (isActive && window.location.hash !== anchor.hash) {
      window.location.hash = anchor.hash
      return
    }
  }
}

function gatherHeaderAnchors () {
  const sidebarLinks = Array.from(document.querySelectorAll('.sidebar-group-items a.sidebar-link'))

  const anchors = Array.from(document.querySelectorAll('a.header-anchor'))
    .filter(x => sidebarLinks.map(x => x.hash).includes(x.hash))

  return anchors
}
</script>

<style src="prismjs/themes/prism-tomorrow.css"></style>
<style src="./styles/theme.styl" lang="stylus"></style>