vue 双向绑定问题$emit无效

父组件变量传给子组件，子组件修改后回传给父组件，无法修改

<div id="app">    <navbar :list="nav" :current="current"></navbar></div><template id="navbar">    <div class="col" v-for="(item,index) in list" @click="setCurrent(index)">        <div :class="{current:current==index}">{{item.name}}</div>    </div></template><script>    new Vue({        el: '#app',        data: {            nav: [{                name: '标题',                type: 'title'            }, {                name: '颜色',                type: 'color'            }],            current: 0        },        methods: {            onCurrent: function(index) {                console.log(index);                this.current = index;            }        },        components: {            navbar: {                props: ['list', 'current'],                template: '#navbar',                methods: {                    setCurrent: function(index) {                        this.$emit('on-current', index);                    }                }            }        }    });    </script>

子组件中setCurrent正常执行，父组件onCurrent却没有反应，而且父组件的current变量未发生变化;

有哪位大大帮看看什么情况