vue多个json人名如何逗号分隔？

 <script src="//unpkg.com/vue/dist/vue.js"></script>

<div id="app">
    <template>
        <span v-for="(item,index) in participant">
            {{
                index == participant.length-1 && item.name || (item.name + ',')
            }}

        </span>
    </template>
</div>

var Main = {
    data () {
      return {
        participant:[{
          name:'张三'
        },{
          name:'李四'
        },{
          name:'王五'
        },{
          name:'赵六'
        }]
      };
    }
  }
var Ctor = Vue.extend(Main)
new Ctor().$mount('#app')

输出：张三, 李四, 王五, 赵六