//父組件
  <ValidateInput
       type="text"
       v-model="emailVal"
       :rules='emailRules'
       placeholder='請輸入郵箱地址'
       ref="inputRef"
  >
  </ValidateInput>
                     
 //子組件
 export default defineComponent({
   name: 'ValidateInput',
   props: {
    rules: Array as PropType <RulesProp>,
     modelValue: String
   },
 }

//v-model簡寫
<ValidateInput
  type="text"
  v-model="emailVal"
  placeholder='請輸入郵箱地址'
  ref="inputRef"
 >
</ValidateInput>

//實際上是
<ValidateInput
  type="text"
  :emailVal="emailVal"
  @update:modelValue="方法"
  placeholder='請輸入郵箱地址'
  ref="inputRef"
 >
</ValidateInput>

//子組件
<template>
  <div class="inputItem">
    <input
      type="text"
      :value="inputRef.val"
      @input="updateValue"
      id="emial"
      >
  </div>
</template>
export default defineComponent({
  name: 'ValidateInput',
  props: {
    rules: Array as PropType <RulesProp>,
    modelValue: String
  },
  setup (props, context) {
    const inputRef = reactive({
      val: props.modelValue || '',
      isError: false,
      message: ''
    })
    const updateValue = (e:KeyboardEvent) => {
      const targetValue = (e.target as HTMLInputElement).value
      inputRef.val = targetValue
      context.emit('update:modelValue', targetValue)
    }
    return {
      inputRef,
      updateValue
    }
  }

 //父組件接受'form-item-created'頻道
 <script lang="ts">
  import { defineComponent, onUnmounted } from 'vue'
  import mitt from 'mitt'
  export const emitter = mitt()
  export default defineComponent({
    name: 'ValidateForm',
    setup () {
      const callback = (test: string) => {
       console.log(test)
     }
     emitter.on('form-item-created', callback)
    onUnmounted(() => {
      emitter.off('form-item-created', callback)
     })
     return {}
   }
})
 </script>
 //子組件發(fā)送信息
 onMounted(() => {
       console.log(inputRef.val)
       emitter.emit('form-item-created', inputRef.val)
 })