Vue.component('x-button', {
  props: ['type'],
  computed: {
    className: function() {
      return `btn-${this.type}`;
    },
  },
  template: `
    <button
      type="button"
      :class="['btn', className]"
      @click="$emit('click', $event)"
    >
      <slot></slot>
    </button>
  `
});

var vue = new Vue({
  el: "#app"
});