core/packages/vue/examples/classic/tree.html

<script src="../../dist/vue.global.js"></script>

<!-- item template -->
<script type="text/x-template" id="item-template">
  <li>
    <div
      :class="{bold: isFolder}"
      @click="toggle"
      @dblclick="changeType">
      {{model.name}}
      <span v-if="isFolder">[{{open ? '-' : '+'}}]</span>
    </div>
    <ul v-show="open" v-if="isFolder">
      <tree-item
        class="item"
        v-for="model in model.children"
        :model="model">
      </tree-item>
      <li class="add" @click="addChild">+</li>
    </ul>
  </li>
</script>
<!-- item script -->
<script>
const TreeItem = {
  name: 'TreeItem', // necessary for self-reference
  template: '#item-template',
  props: {
    model: Object
  },
  data() {
    return {
      open: false
    }
  },
  computed: {
    isFolder() {
      return this.model.children &&
        this.model.children.length
    }
  },
  methods: {
    toggle() {
      if (this.isFolder) {
        this.open = !this.open
      }
    },
    changeType() {
      if (!this.isFolder) {
        this.model.children = []
        this.addChild()
        this.open = true
      }
    },
    addChild() {
      this.model.children.push({
        name: 'new stuff'
      })
    }
  }
}
</script>

<p>(You can double click on an item to turn it into a folder.)</p>

<!-- the app root element -->
<ul id="demo">
  <tree-item class="item" :model="treeData"></tree-item>
</ul>

<script>
const treeData = {
  name: 'My Tree',
  children: [
    { name: 'hello' },
    { name: 'wat' },
    {
      name: 'child folder',
      children: [
        {
          name: 'child folder',
          children: [
            { name: 'hello' },
            { name: 'wat' }
          ]
        },
        { name: 'hello' },
        { name: 'wat' },
        {
          name: 'child folder',
          children: [
            { name: 'hello' },
            { name: 'wat' }
          ]
        }
      ]
    }
  ]
}

Vue.createApp({
  components: {
    TreeItem
  },
  data: () => ({
    treeData
  })
}).mount('#demo')
</script>

<style>
  body {
    font-family: Menlo, Consolas, monospace;
    color: #444;
  }
  .item {
    cursor: pointer;
  }
  .bold {
    font-weight: bold;
  }
  ul {
    padding-left: 1em;
    line-height: 1.5em;
    list-style-type: dot;
  }
</style>