1. 基础用法

<template>
  <div class="content">
    <button @click="flag = !flag">switch</button>
    <transition name="fade">
      <div v-if="flag" class="box"></div>
    </transition>
  </div>
</template>

<script setup lang="ts">
import { ref } from 'vue';
const flag = ref<boolean>(true);
</script>

<style scoped>
.box {
  height: 200px;
  width: 200px;
  background-color: red;
}

.fade-enter-from {
  height: 0;
  width: 0;
}

.fade-enter-active {
  transition: all 1.5s ease;
}


.fade-enter-to {
  height: 200px;
  width: 200px;
}

.fade-leave-from {
  width: 200px;
  height: 200px;
  /* 花里胡哨的旋转 */
  transform: rotate(360deg);
}

.fade-leave-active {
  transition: all 2.5s ease;
}

.fade-leave-to {
  width: 0;
  height: 0;
}

</style>

2. 自定义过渡类名

<template>
  <div class="content">
    <button @click="flag = !flag">switch</button>
    <transition enter-to-class="e-to" enter-active-class="e-active" enter-from-class="e-from" name="fade">
      <div v-if="flag" class="box"></div>
    </transition>
  </div>
</template>

<script setup lang="ts">
import { ref } from 'vue';
const flag = ref<boolean>(true);
</script>

<style scoped>
.box {
  height: 200px;
  width: 200px;
  background-color: red;
}

.e-from {
  height: 0;
  width: 0;
}

.e-active {
  transition: all 1.5s ease;
}


.e-to {
  height: 200px;
  width: 200px;
}

.fade-leave-from {
  width: 200px;
  height: 200px;
  /* 花里胡哨的旋转 */
  transform: rotate(360deg);
}

.fade-leave-active {
  transition: all 2.5s ease;
}

.fade-leave-to {
  width: 0;
  height: 0;
}

</style>

和基础用法中的效果一样。

与基础用法中的区别在于，自定义过渡类名可以结合第三方的库去使用。

比如结合 animate.css 。

<template>
  <div class="content">
    <button @click="flag = !flag">switch</button>
    <transition :duration="{enter:200, leave
    :3000}" leave-active-class="animate__animated animate__bounceOut" enter-active-class="animate__animated animate__bounceIn">
      <div v-if="flag" class="box"></div>
    </transition>
  </div>
</template>

<script setup lang="ts">
import { ref } from 'vue';
import 'animate.css';
const flag = ref<boolean>(true);
</script>

<style scoped>
.box {
  height: 200px;
  width: 200px;
  background-color: red;
}
</style>

其中，:duration="200" 也可以表示 enter 和 leave 的时间都是 200ms 。

3. 八个生命周期

显示 enter 状态：

<template>
  <div class="content">
    <button @click="flag = !flag">switch</button>
    <transition @before-enter="EnterFrom" @enter="EnterActive" @after-enter="EnterTo" @enter-cancelled="EnterCancel">
      <div v-if="flag" class="box"></div>
    </transition>
  </div>
</template>

<script setup lang="ts">
import { ref } from 'vue';
import 'animate.css';
const flag = ref<boolean>(true);

const EnterFrom = (el: Element) => {
  console.log('进入之前');
}
const EnterActive = (el: Element, done: Function) => {
  console.log('进入中（过渡曲线）');
  setTimeout(() => {
    done()
  }, 3000)
}
const EnterTo = (el: Element) => {
  console.log('进入之后（过渡完成）');
}
const EnterCancel = () => {
  // 过渡没到三秒切换，即为过渡效果被打断
  console.log('进入取消（过渡效果被打断）');
}
</script>

<style scoped>
.box {
  height: 200px;
  width: 200px;
  background-color: red;
}
</style>

隐藏 leave 状态：

<template>
  <div class="content">
    <button @click="flag = !flag">switch</button>
    <transition 
    @before-enter="EnterFrom" 
    @enter="EnterActive" 
    @after-enter="EnterTo" 
    @enter-cancelled="EnterCancel"
    @before-leave="LeaveFrom" 
    @leave="LeaveActive" 
    @after-leave="LeaveTo" 
    @leave-cancelled="LeaveCancel"
    
    >
      <div v-if="flag" class="box"></div>
    </transition>
  </div>
</template>

<script setup lang="ts">
import { ref } from 'vue';
import 'animate.css';
const flag = ref<boolean>(true);

const EnterFrom = (el: Element) => {
  console.log('进入之前');
}
const EnterActive = (el: Element, done: Function) => {
  console.log('进入中（过渡曲线）');
  setTimeout(() => {
    done()
  }, 3000)
}
const EnterTo = (el: Element) => {
  console.log('进入之后（过渡完成）');
}
const EnterCancel = () => {
  // 过渡没到三秒切换，即为过渡效果被打断
  console.log('进入取消（过渡效果被打断）');
}
const LeaveFrom = (el: Element) => {
  console.log('离开之前');
}
const LeaveActive = (el: Element, done: Function) => {
  console.log('离开中（过渡曲线）');
}
const LeaveTo = (el: Element) => {
  console.log('离开之后（过渡完成）');
}
const LeaveCancel = () => {
  console.log('离开取消（过渡效果被打断）');
}
</script>

<style scoped>
.box {
  height: 200px;
  width: 200px;
  background-color: red;
}
</style>

声明周期结合第三方库 gsap 去使用。

<template>
  <div class="content">
    <button @click="flag = !flag">switch</button>
    <transition 
    @before-enter="EnterFrom" 
    @enter="EnterActive" 
    @leave="LeaveActive" 
    >
      <div v-if="flag" class="box"></div>
    </transition>
  </div>
</template>

<script setup lang="ts">
import { ref } from 'vue';
import gsap from 'gsap'
const flag = ref<boolean>(true);

const EnterFrom = (el: Element) => {
  gsap.set(el, {
    width:0,
    height:0
  })
}
const EnterActive = (el: Element, done: gsap.Callback) => {
  gsap.to(el, {
    width: 200,
    height: 200,
    onComplete: done
  })
}
const LeaveActive = (el: Element, done: gsap.Callback) => {
  gsap.to(el, {
    width: 0,
    height: 0,
    onComplete: done
  })
}
</script>

<style scoped>
.box {
  height: 200px;
  width: 200px;
  background-color: red;
}
</style>

4. appear

只是在页面刚刚加载的时候进行，也可以结合第三方库去使用。

<template>
  <div class="content">
    <button @click="flag = !flag">switch</button>
    <transition 
    appear
    appear-from-class="from"
    appear-active-class="active"
    appear-to-class="to"
    >
      <div v-if="flag" class="box"></div>
    </transition>
  </div>
</template>

<script setup lang="ts">
import { ref } from 'vue';
import gsap from 'gsap'
const flag = ref<boolean>(true);

</script>

<style scoped>
.box {
  height: 200px;
  width: 200px;
  background-color: red;
}
.from {
  width: 0;
  height: 0;
}
.active {
  transition: all 2s ease;
}
.to {
  width: 200px;
  height: 200px;

}
</style>