Vue 滚动导航栏固定(导航吸顶)

<!-- 吸顶 -->
<template>
    <div class="scroll">
        <div class="header">header</div>
        <div class="nav" :class="navBarFixed == true ? 'navBarWrap' :''">吸顶导航</div>
    </div>
</template>
 
<script>
export default {
  data() {
    return {
        navBarFixed: false,
    };
  },
 
  components: {},
 
  mounted() {
    window.addEventListener("scroll", this.watchScroll);
  },
 
  methods: {
    watchScroll() {
      var scrollTop =
        window.pageYOffset ||
        document.documentElement.scrollTop ||
        document.body.scrollTop;
        console.log(scrollTop)
      //  当滚动超过 90 时，实现吸顶效果
      if (scrollTop > 90) {
        this.navBarFixed = true;
      } else {
        this.navBarFixed = false;
      }
    }
  }
};
</script>
<style scoped>
.scroll{
    height:2000px;
}
.header {
  height: 90px;
  background: red;
  text-align: center;
  color: #fff;
}
.nav{
    padding:15px;
    width:100%;
    box-sizing: border-box;
    background:greenyellow;
    text-align: center;
}
.navBarWrap {
    position:fixed;
    top:0;
    z-index:999;
  }
 
</style>