.native 原生事件
由浏览器自动发布 onclick, ondbclick ...
$emit 自定义事件
需要通过 $emit 发布
<!-- child.vue -->
<!-- echo "native" -->
<div>Click me</div>
<!-- echo "custome" and "native" -->
<div @click="$emit('click')">Click me</div>
<!-- parent.vue -->
<child @click="echo('custom')" @click.native="echo('native')"></child>
