Detailed explanation of how to use Vue self-nested tree components

<template>
  <ul v-show="isShow" ref="user-tree">
    <li v-for="(item, idx) in userList" :key="idx">
      <div>
        <!-- Multi-select user tree -->
        <input
          class="primary"
          type="checkbox"
          v-model="selectUsers1"
          :value="item.userId"
          v-show="isCheck"
        />
        <!-- Single-select user tree -->
        <span
          @click="onSelect(item)"
          :style="{
            color: selectUser1 == item.userId ? 'red' : '',
            cursor: 'pointer',
          }"
        >
          <i class="iconfont icon-user"></i> {{ item.userName }}</span
        >
        <!-- Expand the user tree -->
        <i
          class="iconfont icon-right"
          v-if="item.haveChild"
          @click="expandItem(idx)"
        ></i>
      </div>
      <!-- Nested user tree -->
      <user-tree
        :user-id="item.userId"
        v-if="item.haveChild"
        :is-show.sync="item.isShow"
        :select-user.sync="selectUser1"
        :select-users.sync="selectUsers1"
        :is-check="isCheck"
      ></user-tree>
    </li>
  </ul>
</template>

<script> 
export default {
  name: "user-tree", //Defined as component name, otherwise self-nesting will report an error that the component itself is not registered props: {
    isShow: {//Whether to expand the user list type: Boolean,
      default: false
    },
    userId: {//Current user tree parent id
      type: Number,
      default: 0
    },
    selectUser: {//Currently selected user id
      type: Number,
      default: 0
    },
    selectUsers: {//Multiple selection users type: Array,
      default: function () {
        return [];
      }
    },
    isCheck: {//Whether to select multiple options type: Boolean,
      default: false
    }
  },

  data: () => ({
    userList: [], //User list selectUser1: 1, //Single selection of user selectUsers1: [], //Multiple selection of users isLoad: true
  }),
  watch:
    selectUser1 () {//Single-select user, current level synchronized to parent levelif (this.selectUser1 != this.selectUser) {
        this.$emit("update:select-user", this.selectUser1);
      }
    },
    selectUser () {//Single selection of user, current level is synchronized with parent levelif (this.selectUser1 != this.selectUser) {
        this.selectUser1 = this.selectUser;
      }
    },
    selectUsers1 () {//Multiple selections, current level synchronized to parent levelif (this.selectUsers1 != this.selectUsers) {
        this.$emit("update:select-users", this.selectUsers1);

      }
    },
    selectUsers () {//Multiple selections, current level synchronized with parent levelif (this.selectUsers1 != this.selectUsers) {
        this.selectUsers1 = this.selectUsers;
      }
    },
    isShow() {
      if (this.isShow) {
        this.getUserList();
      }
    }
  },
  methods: {
    onSelect (item) {//Single selection user this.$emit("update:select-user", item.userId);

    },

    expandItem (idx) {//Expand the user tree if (this.userList[idx].isShow) {
        this.userList[idx].isShow = false;
      } else {
        this.userList[idx].isShow = true;
      }

    },
    getUserList () {
      var list = [];
      for (var i = 0; i < 10; i++) {
        var userId = Math.round(Math.random() * 10000);
        list.push({
          userId: userId,
          userName: "user-" + userId,
          haveChild: i % 2, //Whether there is a subtree isShow: false //Whether to display the subtree });
      }
      this.userList = list;


    },

  },
  mounted () {

    if (this.userId == 1) {//The current parent userId is the root user id, so load and expand the user tree this.getUserList(this.userId);
    }
  }
};
</script>

<div>{{ selectUser }}</div>
    <div>
      <span v-for="item in selectUsers" :key="item">【{{ item }}】</span>
    </div>
    <user-tree
      :user-id="1"
      :is-show="true"
      :select-user.sync="selectUser"
      :select-users.sync="selectUsers"
      :is-check="true"
></user-tree>