<template>
  <div>
    <div v-for="item in items" :key="item.id" class="item">
      {{ item.name }}
    </div>
  </div>
</template>

.item {
  transition: all 0.5s;
}

.item-enter-active,
.item-leave-active {
  transition: all 0.5s;
}

.item-enter,
.item-leave-to {
  opacity: 0;
  transform: translateY(20px);
}

<script>
export default {
  data() {
    return {
      items: [
        { id: 1, name: 'Item 1' },
        { id: 2, name: 'Item 2' },
        { id: 3, name: 'Item 3' }
      ]
    };
  },
  mounted() {
    // 在一段时间后添加一个新的div元素到列表中
    setTimeout(() => {
      this.items.push({ id: 4, name: 'Item 4' });
    }, 1000);
  }
};
</script>