<template>
 <button class="disable-hover button ion-button"
     :class="[modeClass,typeClass,shapeClass,sizeClass,colorClass,roleClass,strongClass]">
  <span class="button-inner">
   <slot></slot>
  </span>
  <div class="button-effect"></div>
 </button>
</template>

<ion-button @click.native="primary()" color="primary">primary</ion-button>

<template>
 <button class="disable-hover button ion-button" @click="_click"
     :class="[modeClass,typeClass,shapeClass,sizeClass,colorClass,roleClass,strongClass]">
  <span class="button-inner">
   <slot></slot>
  </span>
  <div class="button-effect"></div>
 </button>
</template>

<script type="text/babel">
export default{
  ....
  ....
  methods: {
   _click: function () {
    this.$emit('click', function () {
     alert('inner')
    })
   }
  }
}
</script>

<ion-button @click="primary()" color="primary">primary</ion-button>