如何使用Vue 3中的Teleport组件实现全局通知功能

<template>
  <div class="notification">
    {{ message }}
  </div>
</template>

<script>
export default {
  props: ['message']
}
</script>

<style scoped>
.notification {
  position: fixed;
  top: 0;
  right: 0;
  left: 0;
  padding: 10px;
  background-color: #f0f0f0;
  color: #333;
  text-align: center;
}
</style>

<template>
  <teleport to="#notification-portal">
    <Notification v-if="showNotification" :message="notificationMessage" />
  </teleport>
  <div id="notification-portal"></div>
</template>

<script>
import { ref, watch } from 'vue'
import Notification from './Notification.vue'

export default {
  components: {
    Notification
  },
  setup() {
    const showNotification = ref(false)
    const notificationMessage = ref('')

    watch(notificationMessage, () => {
      showNotification.value = !!notificationMessage.value
      if (showNotification.value) {
        setTimeout(() => {
          notificationMessage.value = ''
        }, 3000)
      }
    })

    return {
      showNotification,
      notificationMessage
    }
  }
}
</script>

<style>
#notification-portal {
  z-index: 9999;
}

<template>
  <div id="app">
    <h1>Vue 3全局通知功能演示</h1>
    <NotificationPortal />
    <!-- 这里是其他组件的内容 -->
  </div>
</template>

<script>
import NotificationPortal from './NotificationPortal.vue'

export default {
  components: {
    NotificationPortal
  }
}
</script>

notificationMessage.value = '这是一条通知的内容'