页面锚点滚动2

<template>
  <div class="lab-group-switch">
    <ul>
      <template v-for="(group, index) in labGroups">
        <li
          :key="index"
          class="week-num relative"
          :class="{ 'active': activeIndex === index }"
          @click="switchGroup(index)"
        >
          <span>{{ index }}周</span>
          <span class="week-title">
            {{ group.name }}
          </span>
        </li>
      </template>
      <li
        v-show="!isPositionTop"
        class="week-num relative"
        @click="backTop"
      >
        <img
          src="~assets/images/pages/courses/labs/icon-top.png"
          alt=""
        >
        <span class="week-title">
          回到顶部
        </span>
      </li>
    </ul>
  </div>
</template>

<script>
export default {
  props: {
    labGroups: {
      type: Array,
      default: () => [],
    },
  },
  data() {
    return {
      isPositionTop: true,
      activeIndex: 0,
      labListContainer: null,
      weekNodeList: [],
      timer: 0,
    }
  },
  mounted() {
    if (document.documentElement.scrollTop > 0) {
      this.isPositionTop = true
    } else {
      this.isPositionTop = false
    }
    let nodeList = []
    for (let index = 0; index < this.labGroups.length; index++) {
      const node = document.querySelector(`#week-${index}`)
      nodeList.push(node)
    }
    this.nodeList = nodeList
    this.labListContainer = document.querySelector('.course-lab-list-container')
    window.addEventListener('scroll', this.handleScroll)
  },
  destroyed() {
    // 移除滚动监听
    window.removeEventListener('scroll', this.handleScroll)
  },
  methods: {
    // 分组切换
    switchGroup(index) {
      if (this.activeIndex === index) {
        return
      }
      this.activeIndex = index
      const node = document.querySelector(`#week-${index}`)
      const windowScrollHeight = document.documentElement.scrollTop
      const nodeOffsetTop = node.getClientRects()[0].top
      let scrollTop = 0
      document.documentElement.scrollTop =
        windowScrollHeight + nodeOffsetTop - 100
    },
    // 回到顶部
    backTop() {
      document.documentElement.scrollTop = 0
      this.activeIndex = 0
    },
    // 处理滚动事件
    handleScroll() {
      if (!!this.labListContainer.style.display) {
        return
      }
      if (document.documentElement.scrollTop > 0) {
        this.isPositionTop = false
      } else {
        this.isPositionTop = true
      }
      if (this.timer) {
        return
      }
      // 100 ms 执行一次
      this.timer = setTimeout(() => {
        this.nodeList.map((node, index) => {
          const nodeOffsetTop = node.getClientRects()[0].top
          if (nodeOffsetTop < 120) {
            this.activeIndex = index
          }
        })
        this.timer = 0
      }, 100)
    },
  },
}
</script>

<style lang="scss" scoped>
.lab-group-switch {
  position: fixed;
  left: 10px;
  width: 50px;
  top: 100px;
  padding: 5px 6px;
  list-style: none;
  border-radius: 5px;
  background-color: #fff;
  box-shadow: 0 2px 4px 0 rgba(0, 0, 0, 0.2);
  z-index: 9;
  > ul {
    padding: 0;
    margin: 0;
    list-style: none;
    > li {
      position: relative;
      height: 40px;
      padding-top: 10px;
      font-size: 0.9rem;
      text-align: center;
      color: #999;
      border-bottom: 1px solid #eee;
      cursor: pointer;
      &.active {
        color: #08bf91;
      }
      .week-title {
        position: absolute;
        opacity: 0;
        visibility: hidden;
        left: 20px;
        top: 5px;
        padding: 5px 15px;
        background: #fff;
        border: 1px solid #eee;
        border-radius: 5px;
        font-size: 12px;
        white-space: nowrap;
        text-align: left;
        color: #08bf91;
        transition: all 0.3s ease-out;
        pointer-events: none;
        &::after {
          content: '';
          position: absolute;
          left: -6px;
          top: 35%;
          background: #fff;
          height: 10px;
          width: 10px;
          transform: rotateZ(45deg);
          border-left: 1px solid #eee;
          border-bottom: 1px solid #eee;
        }
      }
      &:hover {
        .week-title {
          visibility: visible;
          opacity: 1;
          left: 50px;
        }
      }
    }
  }
}
</style>