<template>
  <div class="sidebar-button" @click="$emit('toggle-sidebar')">
    <svg class="icon" :style="{color:scrollFlag?'white':'black'}" xmlns="http://www.w3.org/2000/svg" aria-hidden="true" role="img" viewBox="0 0 448 512">
      <path fill="currentColor" d="M436 124H12c-6.627 0-12-5.373-12-12V80c0-6.627 5.373-12 12-12h424c6.627 0 12 5.373 12 12v32c0 6.627-5.373 12-12 12zm0 160H12c-6.627 0-12-5.373-12-12v-32c0-6.627 5.373-12 12-12h424c6.627 0 12 5.373 12 12v32c0 6.627-5.373 12-12 12zm0 160H12c-6.627 0-12-5.373-12-12v-32c0-6.627 5.373-12 12-12h424c6.627 0 12 5.373 12 12v32c0 6.627-5.373 12-12 12z" class=""></path>
    </svg>
  </div>
</template>
<script>
export default {
  data(){
    return{
      scrollFlag: false
    }
  },
  watch:{
    //监听路由，处理导航栏样式
    $route(to,from){
      this.handleScroll();
    }
  },
  methods:{
    handleScroll () {
      let _this=this;
      let scrollTop = window.pageYOffset || document.documentElement.scrollTop || document.body.scrollTop
      // console.log(scrollTop)
      let index = this.$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");
      }
    }
  },
  mounted(){
     this.handleScroll()
     window.addEventListener('scroll', this.handleScroll)
  }
}
</script>
<style lang="stylus">
.sidebar-button
  cursor pointer
  display none
  width 1.25rem
  height 1.25rem
  position absolute
  padding 0.6rem
  top 0.6rem
  left 1rem
  .icon
    display block
    width 1.25rem
    height 1.25rem
    color white
@media (max-width: $MQMobile)
  .sidebar-button
    display block
</style>
