//1.调用ref函数 -> ref对象
const h1Ref = ref(null)
const comRef = ref(null)
//组件挂载完毕之后才能获取
onMounted(()=>{
  console.log(h1Ref.value);
  console.log(comRef.value);
})

  <div class="father">
    <!-- 通过ref标识绑定ref对象 -->
    <h2 ref="h1Ref">父组件</h2>
    <HelloWorldVue :count="count" message="father message" @get-message="getMessage" ref="comRef"></HelloWorldVue>
  </div>

绑定之后结果

默认情况下在

子组件中

const name = ref('test name')
defineExpose({
  name
})