<div class="tree">
 <nav class='navbar'>
 <ul class='nav nav-stacked'>
 <template v-for='item in menus'>
 <li role='presentation' v-if='!item.children'><a href="#">{{item.text}}</a></li>
 <li role='presentation' v-if='item.children'><a href="#" v-on:click='toggleChildren(item)'>{{item.text}}<span class='glyphicon' v-bind:class='{ "glyphicon-chevron-right": !item.expanded, "glyphicon-chevron-down": item.expanded }'></span></a>
 <ul v-show='item.expanded' class="childs">
 <li v-for='child in item.children'><a href="#">{{child.text}}</a></li>
 </ul>
 </li>
 </template>
 </ul>
 </nav>
</div>

methods: {
 toggleChildren: function(item) {
 item.expanded = !item.expanded;
 },
 },
 data() {
 return {
 menus:[{
 text:'水果',
 expanded:false,
 children:[{
 text:'蘋果',
 },{
 text:'荔枝'
 },{
 text:'葡萄'
 },{
 text:'火龍果'
 }]
 },{
 text:'好吃的',
 expanded:false,
 children:[{
 text:'糖',
 },{
 text:'面包'
 },{
 text:'火腿'
 },{
 text:'薯片'
 },{
 text:'碎碎面'
 }]
 },{
 text:'飲料',
 expanded:false,
 children:[]
 }]
 }
 },