meface/docs/.vuepress/theme/components/Navbar.vue

<template>
  <header class="navbar " v-bind:class="{'index-header-transparent':scrollFlag}">
    <SidebarButton @toggle-sidebar="$emit('toggle-sidebar')"/>

    <router-link
      :to="$localePath"
      class="home-link">
      <img
        class="logo"
        v-if="$themeConfig.logo"
        :src="$withBase($themeConfig.logo)"
        :alt="$siteTitle">
      <span
        ref="siteName"
        class="site-name"
        v-if="$siteTitle">{{ $siteTitle }}</span>
    </router-link>

    <div
      class="links"
      :style="linksWrapMaxWidth ? {
        'max-width': linksWrapMaxWidth + 'px'
      } : {}">

      <Mode />
      <AlgoliaSearchBox
        v-if="isAlgoliaSearch"
        :options="algolia"/>
      <SearchBox v-else-if="$themeConfig.search !== false && $frontmatter.search !== false"/>
      <NavLinks class="can-hide"/>
    </div>
  </header>
</template>

<script>
import AlgoliaSearchBox from '@AlgoliaSearchBox'
import SearchBox from '@SearchBox'
import SidebarButton from '@theme/components/SidebarButton'
import NavLinks from '@theme/components/NavLinks'
import Mode from '@theme/components/Mode'

export default {
  components: { SidebarButton, NavLinks, SearchBox, AlgoliaSearchBox, Mode },

  data () {
    return {
      linksWrapMaxWidth: null,
      scrollFlag:true
    }
  },
  watch:{
    //监听路由，处理导航栏样式
    $route(to,from){
      this.handleScroll();
    }
  },

  mounted () {
    const MOBILE_DESKTOP_BREAKPOINT = 719 // refer to config.styl
    const NAVBAR_VERTICAL_PADDING = parseInt(css(this.$el, 'paddingLeft')) + parseInt(css(this.$el, 'paddingRight'))
    const handleLinksWrapWidth = () => {
      if (document.documentElement.clientWidth < MOBILE_DESKTOP_BREAKPOINT) {
        this.linksWrapMaxWidth = null
      } else {
        this.linksWrapMaxWidth = this.$el.offsetWidth - NAVBAR_VERTICAL_PADDING -
          (this.$refs.siteName && this.$refs.siteName.offsetWidth || 0)
      }
    }
    handleLinksWrapWidth()
    window.addEventListener('resize', handleLinksWrapWidth, false)
    window.addEventListener('scroll', this.handleScroll)
    this.handleScroll()
  },

  computed: {
    algolia () {
      return this.$themeLocaleConfig.algolia || this.$themeConfig.algolia || {}
    },

    isAlgoliaSearch () {
      return this.algolia && this.algolia.apiKey && this.algolia.indexName
    }
  },

  methods: {
    throttle (func, delay) {
      let timer = null
      let startTime = Date.now()

      return function () {
        const curTime = Date.now()
        const remaining = delay - (curTime - startTime)
        const context = this
        const args = arguments

        clearTimeout(timer)
        if (remaining <= 0) {
          func.apply(context, args)
          startTime = Date.now()
        } else {
          timer = setTimeout(func, remaining)
        }
      }
    },
    handleScroll () {
      let _this=this;
      var scrollTop = window.pageYOffset || document.documentElement.scrollTop || document.body.scrollTop
      // console.log(scrollTop)
      var index = this.$route.path;
      //当在首页的顶部时才加样式
      if(scrollTop==0&&index== '/'){
        _this.scrollFlag=true
        // console.log("true");
      }else{
        _this.scrollFlag=false
        // console.log("false");
      }
    }
  }
}

function css (el, property) {
  // NOTE: Known bug, will return 'auto' if style value is 'auto'
  const win = el.ownerDocument.defaultView
  // null means not to return pseudo styles
  return win.getComputedStyle(el, null)[property]
}
</script>

<style lang="stylus">
@require '../styles/mode.styl'

$navbar-vertical-padding = 0.7rem
$navbar-horizontal-padding = 1.5rem

.navbar
  padding $navbar-vertical-padding $navbar-horizontal-padding
  line-height $navbarHeight - 1.4rem
  box-shadow var(--box-shadow)
  background var(--background-color)
  a, span, img
    display inline-block
  .logo
    height $navbarHeight - 1.4rem
    min-width $navbarHeight - 1.4rem
    margin-right 0.8rem
    vertical-align top
    border-radius 50%
  .site-name
    font-size 1.2rem
    font-weight 600
    color var(--text-color)
    position relative
  .links
    padding-left 1.5rem
    box-sizing border-box
    white-space nowrap
    font-size 0.9rem
    position absolute
    right $navbar-horizontal-padding
    top $navbar-vertical-padding
    display flex
    background-color var(--background-color)
    .search-box
      flex: 0 0 auto
      vertical-align top

@media (max-width: $MQMobile)
  .navbar
    padding-left 4rem
    .can-hide
      display none
    .links
      padding-left .2rem

.index-header-transparent {
  background: transparent;
  //background-color var(--background-color)
  -webkit-transition: all .5s ease;
  transition: all .5s ease;

  .links {
    //background-color var(--background-color)
    background: transparent;
  }
  .home-link {
    .site-name {
      color white
    }
  }
  .nav-item{
    .dropdown-title,.nav-link{
      color white
      .iconfont{
        color white
      }
    }
    .nav-dropdown{
      background white
      .nav-link{
        color black
      }
    }
  }
}

//.index-header-transparent .nav-links a {
//  color: var(--text-color);
//}
</style>