你知道vue data为什么是一个函数

function Person(){
 }
 Person.prototype.datas={
   a:"c",
   f:'h'
 }
 var person1 = new Person()
 var person2 = new Person()
 person2.datas.a="wewew"
 console.log(person2)
 console.log(person1)

function Person(){
    this.datas = this.sayHello()//this指向调用它的对象
  }
  Person.prototype.sayHello = function () {
      return{
        d:1,
        b:2
      }
    };
  var person1 = new Person()
  var person2 = new Person()
  person2.datas.d="wewew"
  console.log(person1)
  console.log(person2)

<em id="__mceDel">ButtonTest.vue<br><template>
  <div>
    <div>{{ count }}</div>
    <button @click="onAdd">增加</button>
  </div>
</template>
<script>
export default {
  data() {
    return {
      count: 0,
    };
  },
  methods: {
    onAdd() {
      this.count++;
    },
  },
};
</script><br></em>

Home.vue
<template>
  <div class="home">
    <button-test></button-test>
    <button-test></button-test>
  </div>
</template>
 
<script>
import ButtonTest from "@/components/ButtonTest.vue";
export default {
  name: "Home",
  components: {
    ButtonTest,
  },
};
</script>