SOURCE

//var data = { status: 'Critical'};
Vue.component('my-cmp',{
   data:function() {
     //return data;
     return {
       status: 'Critical'
     }
   },
  template: '<p>Server Status: {{ status }}（<button @click="changeStatus">Change</button>）</p>',
  methods: {
    changeStatus: function() {
      this.status = 'Normal';
    }
  }
});

new Vue({
  el: '#app',
  
});

<script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js">
</script>
<div id="app">
  <my-cmp></my-cmp>
  <my-cmp></my-cmp>
</div>