vue/examples/composition/tree.html

<script src="../../dist/vue.min.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-if="isFolder" v-show="open">
      <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 { reactive, computed, toRefs } = Vue

  const TreeItem = {
    name: 'TreeItem', // necessary for self-reference
    template: '#item-template',
    props: {
      model: Object
    },
    setup(props) {
      const state = reactive({
        open: false,
        isFolder: computed(() => {
          return props.model.children && props.model.children.length
        })
      })

      function toggle() {
        state.open = !state.open
      }

      function changeType() {
        if (!state.isFolder) {
          Vue.set(props.model, 'children', [])
          addChild()
          state.open = true
        }
      }

      function addChild() {
        props.model.children.push({ name: 'new stuff' })
      }

      return {
        ...toRefs(state),
        toggle,
        changeType,
        addChild
      }
    }
  }
</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' }]
          }
        ]
      }
    ]
  }

  new Vue({
    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>