const alert2 = {
  data() {
    return {
      text: '元件2'
    };
  },
  template: `<div class="alert alert-primary" role="alert">
    {{ text }}
    <alert1></alert1>
  </div>`
}
const alert3 = {
  data() {
    return {
      text: '元件3'
    };
  },
  template: `<div class="alert alert-primary" role="alert">
    {{ text }}
  </div>`
}
const app = Vue.createApp({
  data() {
    return {
      text: '根元件 的 text',
    };
  },
  components:{
    alert2
  }
})
// 全域註冊方法2
app.component('alert1',{
  data() {
    return {
      text: '元件1'
    };
  },
  template: `<div class="alert alert-primary" role="alert">
      {{ text }}
      <alert2></alert2>
    </div>`
});

app.mount('#app');