SOURCE

console.log('vue', Vue)

// 定义一个名为 button-counter 的新组件
var componentA = Vue.component('button-counter', {
  data: function () {
    return {
      count: 0
    }
  },
  template: '<button v-on:click="count++">You clicked me {{ count }} times.</button>'
})

var app = new Vue({
  el: '#app',
  data: {
    message: 'Hello Vue!'
  }
})

// console.log('app', app)

<div id="app">
    {{ message }}

    <button-counter></button-counter>
</div>