import Vue from 'vue'

/**
 * @param Component 组件实例的选项对象
 * @param props 组件实例中的prop
 */
export function create(Component, props) {
 const comp = new (Vue.extend(Component))({ propsData: props }).$mount()
 
 document.body.appendChild(comp.$el)

 comp.remove = () => {
  document.body.removeChild(comp.$el)

  comp.$destroy()
 }

 return comp
}

import Vue from 'vue'

export function create(Component, props) {
 // 借鸡生蛋new Vue({render() {}}),在render中把Component作为根组件
 const vm = new Vue({
  // h是createElement函数，它可以返回虚拟dom
  render(h) {
   console.log(h(Component,{ props }));
   
   // 将Component作为根组件渲染出来
   // h(标签名称或组件配置对象，传递属性、事件等，孩子元素)
   return h(Component, { props })
  }
 }).$mount() // 挂载是为了把虚拟dom变成真实dom
 // 不挂载就没有真实dom
 // 手动追加至body
 // 挂载之后$el可以访问到真实dom
 document.body.appendChild(vm.$el)

 console.log(vm.$children);
 
 // 实例
 const comp = vm.$children[0]

 // 淘汰机制
 comp.remove = () => {
  // 删除dom
  document.body.removeChild(vm.$el)

  // 销毁组件
  vm.$destroy()
 }

 // 返回Component组件实例
 return comp
}

<template>
 <div class="a">
  <h2>{{ title }}</h2>
  <p>{{ data }}</p>
 </div>
</template>

<script>
export default {
 props: {
  title: {
   type: String,
   default: "hello world!"
  },
  message: {
   type: String,
   default: "o(∩_∩)o 哈哈"
  },
  duration: {
   type: Number,
   default: 1000
  }
 },
 data() {
  return {
   data: "我是a组件",
  };
 },
 created() {
  let num = 1
  
  const timer = setInterval(() => {
   this.data = num++
  }, this.duration)

  this.$once("hook: beforeDestroy", () => clearInterval(timer))
 }
};
</script>

<style>
.a {
 position: fixed;
 width: 100%;
 top: 16px;
 left: 0;
 text-align: center;
 pointer-events: none;
 background-color: #fff;
 border: grey 3px solid;
 box-sizing: border-box;
}
</style>

<template>
 <div class="b">
  <button @click="createA">创建</button>
 </div>
</template>

<script>
import A from "@/components/A.vue"
import { create } from "@/utils/create.js"
export default {

 components: {
  A,
 },
 methods: {
  createA() {
   // 创建A组件，并挂载到body上
   create(A, { title: "vue", message: "么么哒" })
  }
 },
};
</script>