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<!-- item template -->
<script type="text/x-template" id="item-template">
  <li>
    <div
      :class="{bold: isFolder}"
      @click="toggle"
      @dblclick="makeFolder">
      {{ item.name }}
      <span v-if="isFolder">[{{ isOpen ? '-' : '+' }}]</span>
    </div>
    <ul v-show="isOpen" v-if="isFolder">
      <tree-item
        class="item"
        v-for="(child, index) in item.children"
        :key="index"
        :item="child"
        @make-folder="$emit('make-folder', $event)"
        @add-item="$emit('add-item', $event)"
      ></tree-item>
      <li class="add" @click="$emit('add-item', item)">+</li>
    </ul>
  </li>
</script>

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

<!-- the demo root element -->
<ul id="demo">
  <tree-item
    class="item"
    :item="treeData"
    @make-folder="makeFolder"
    @add-item="addItem"
  ></tree-item>
</ul>
// demo data
var 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' }
          ]
        }
      ]
    }
  ]
}

// define the tree-item component
Vue.component('tree-item', {
  template: '#item-template',
  props: {
    item: Object
  },
  data: function () {
    return {
      isOpen: false
    }
  },
  computed: {
    isFolder: function () {
      return this.item.children &&
        this.item.children.length
    }
  },
  methods: {
    toggle: function () {
      if (this.isFolder) {
        this.isOpen = !this.isOpen
      }
    },
    makeFolder: function () {
      if (!this.isFolder) {
      	this.$emit('make-folder', this.item)
        this.isOpen = true
      }
    }
  }
})

// boot up the demo
var demo = new Vue({
  el: '#demo',
  data: {
    treeData: treeData
  },
  methods: {
  	makeFolder: function (item) {
    	Vue.set(item, 'children', [])
      this.addItem(item)
    },
    addItem: function (item) {
    	item.children.push({
        name: 'new stuff'
      })
    }
  }
})
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;
}