vue实现三级导航展示和隐藏

<template>
  <div id="app">
    <img alt="Vue logo" src="./assets/logo.png" />
    <HelloWorld msg="Welcome to Your Vue.js App" />
    <div class="first" v-for="(item, key) in navLists" :key="key">
      <li>
        <span @click="handleClick(key)"> {{ item.title }}</span>
        <div
          v-for="(item2, key2) in item.child"
          :key="key2"
          class="second"
          v-show="show2 && currIndex == key"
        >
          <p @click="secondClick(key2)">{{ item2.subTitle }}</p>
          <div
            v-for="(item3, key3) in item2.threeChild"
            :key="key3"
            class="three"
           v-show="show3 && currIndex2 == key2"
          >
            {{ item3.threeTitle }}
          </div>
        </div>
      </li>
    </div>
  </div>
</template>
 
<script>
import HelloWorld from "./components/HelloWorld.vue";
 
export default {
  name: "App",
  components: {
    HelloWorld,
  },
  data() {
    return {
      i: 0,
 
      show3: false,
      show2: false,
      navLists: [
        {
          title: "项目信息",
          child: [
            {
              subTitle: "项目简介",
              esubTitle: "#projectIntroduction",
              threeChild: [
                { threeTitle: "三级导航" },
                { threeTitle: "三级导航" },
                { threeTitle: "三级导航" },
              ],
            },
            {
              subTitle: "样品信息",
              threeChild: [
                { threeTitle: "三级导航22" },
                { threeTitle: "三级导航22" },
                { threeTitle: "三级导航22" },
              ],
            },
 
            {
              subTitle: "样品信息",
              threeChild: [
                { threeTitle: "三级导航33" },
                { threeTitle: "三级导航33" },
                { threeTitle: "三级导航33" },
              ],
            },
          ],
        },
        {
          title: "项目信息2",
          child: [
            {
              subTitle: "项目简介22",
              threeChild: [
                { threeTitle: "三级导航44" },
                { threeTitle: "三级导44" },
                { threeTitle: "三级导航22" },
              ],
            },
            {
              subTitle: "样品信息22",
            },
          ],
        },
        {
          title: "项目信息3",
          eTitle: "#projectMessage",
          child: [
            {
              subTitle: "项目简介33",
              esubTitle: "#projectIntroduction",
            },
            {
              subTitle: "样品信息33",
              esubTitle: "#sampleInformation",
            },
          ],
        },
        {
          title: "项目信息2",
          child: [
            {
              subTitle: "项目简介22",
            },
            {
              subTitle: "样品信息22",
            },
          ],
        },
        {
          title: "项目信息3",
          child: [
            {
              subTitle: "项目简介33",
            },
            {
              subTitle: "样品信息33",
            },
          ],
        },
      ],
 
      currIndex: "", //当前索引
      spanIndex: [], //索引数组
      arrIndex: "", //用于判断是否做索引数组找到当前索引。-1为找不到,0找到了。
 
      currIndex2: "", //二级导航当前索引
      spanIndex2: [], //索引数组
      arrIndex2: "", //用于判断是否做索引数组找到当前索引。-1为找不到,0找到了。
    };
  },
  methods: {
    handleClick(index) {
      // 初始化三级导航，默认不显示。
      this.show3 =false;
      this.spanIndex2.splice(-1, 1);
 
      // 当前索引=index
      this.currIndex = index;
      console.log("当前索引index", index);
      // 判断当前索引是否在索引数组spanIndex中。arrIndex的值只有两种结果，-1未找到。0找到了。
      this.arrIndex = this.spanIndex.indexOf(index);
      console.log("arrIndex", this.arrIndex);
 
      if (this.arrIndex == 0) {
        //arrIndex ==0，找到索引了，在索引数组spanIndex删除该索引,隐藏二级导航。
        this.spanIndex.splice(this.arrIndex, 1);
        this.show2 = false;
      } else {
        // arrIndex ==-1,没有找到，splice(-1,1)从spanIndex数组结尾处删除1个值，并将当前索引添加到索引数组spanIndex，show2为true，展示二级导航，
        this.spanIndex.splice(this.arrIndex, 1);
        this.spanIndex.push(index);
        this.show2 = true;
      }
      
      console.log("索引数组", this.spanIndex);
    },
 
    secondClick(index) {
      console.log(index);
      // 当前索引=index
      this.currIndex2 = index;
      // 判断当前索引是否在索引数组spanIndex中。arrIndex的值只有两种结果，-1未找到。0找到了。
      this.arrIndex2 = this.spanIndex2.indexOf(index);
      console.log("arrIndex2", this.arrIndex2);
 
      if (this.arrIndex2 == 0) {
        //arrIndex ==0，找到索引了，在索引数组spanIndex删除该索引,隐藏二级导航。
        this.spanIndex2.splice(this.arrIndex2, 1);
        this.show3 = false;
      } else {
        // arrIndex ==-1,没有找到，splice(-1,1)从spanIndex数组结尾处删除1个值，并将当前索引添加到索引数组spanIndex，show2为true，展示二级导航，
        this.spanIndex2.splice(this.arrIndex2, 1);
        this.spanIndex2.push(index);
        this.show3 = true;
      }
       console.log("索引数组2", this.spanIndex2);
    },
  },
};
</script>
 
<style>
p {
  padding: 5px 0;
  margin-block-start: 0;
  margin-block-end: 0;
}
#app {
  font-family: Avenir, Helvetica, Arial, sans-serif;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-align: center;
  color: #2c3e50;
  margin-top: 60px;
}
.first {
  width: 200px;
  font-size: 24px;
  font-weight: bold;
  /* height: 60px; */
  /* background:red; */
}
.first:hover {
  cursor: pointer;
 
  /* color:red; */
}
.second {
  font-size: 18px;
  font-weight: normal;
  background: #eee;
  margin-left: 50px;
}
.three {
  background: yellow;
  margin-left: 20px;
  font-size: 14px;
}
</style>