1.dom上写上ref 

2setup函数内部写上ref

3retrun 出来（重点）

<template>
  <div>
    <input type="text" v-model="name">
    <h1 ref="stateDom">hh</h1>
  </div>
</template>
 
<script lang="ts">
import { watchFile } from "fs";
import { stringify } from "querystring";
import { defineComponent,reactive,toRefs,computed,h,ref, customRef, onMounted,watchEffect } from "vue";
//这是防抖的
 function Items(params:string,times:number=2000) {
    let time:any=null;
      return customRef((track,trigger)=>{
          return {
            get(){
              console.log('00')
                 track();
              return params;
            },
            set(newVal){
                clearTimeout(time)
                time=setTimeout(()=>{
                  params=newVal;
                  trigger();
                  // gge();
                },times)
            }
          }
      })
  }
export default defineComponent({
  name: "HelloWorld",
  props: {
    msg: String,
  },
 
  setup() {
    const stateDom=ref(null)
  onMounted(()=>{
    console.log(stateDom.value)
    // watchEffect(()=>{
    //   console.log(stateDom.value)
    // })
  })
    
    return {
      name,
      stateDom
    }
 
    // return {
    //   ...render,
    //   ...sums,
    //   // ...Computed,
    //   ...toRefs(state),
    //   ...methods,
    // };
  },
});
</script>