Vue 3 Transitions for Element Entry/Exit

<template>
  <div>
    <button @click="show = !show">Toggle Message</button>
    <Transition name="slide-fade">
      <p v-if="show" class="message">Hello from Vue 3!</p>
    </Transition>

    <h2>Transition Group Example</h2>
    <button @click="addNumber">Add Number</button>
    <button @click="removeNumber">Remove Number</button>
    <TransitionGroup name="list" tag="ul">
      <li v-for="item in items" :key="item" class="list-item">
        {{ item }}
      </li>
    </TransitionGroup>
  </div>
</template>

<script setup>
import { ref } from 'vue';

const show = ref(true);

const items = ref([1, 2, 3, 4, 5]);
let nextNum = 6;

function addNumber() {
  const randIndex = Math.floor(Math.random() * items.value.length);
  items.value.splice(randIndex, 0, nextNum++);
}

function removeNumber() {
  if (items.value.length > 0) {
    const randIndex = Math.floor(Math.random() * items.value.length);
    items.value.splice(randIndex, 1);
  }
}
</script>

<style>
/* Basic element transition */
.slide-fade-enter-active {
  transition: all 0.3s ease-out;
}
.slide-fade-leave-active {
  transition: all 0.8s cubic-bezier(1, 0.5, 0.8, 1);
}
.slide-fade-enter-from, .slide-fade-leave-to {
  transform: translateX(20px);
  opacity: 0;
}

/* List transition */
.list-item {
  transition: all 0.8s ease;
  display: inline-block; /* For list items */
  margin-right: 10px;
}
.list-enter-from, .list-leave-to {
  opacity: 0;
  transform: translateY(30px);
}
/* ensure leaving items are taken out of layout flow so that moving
   animations can be calculated correctly. */
.list-leave-active {
  position: absolute;
}
</style>