DDR爱好者之家 Design By 杰米

常见示例

最常见的多标签过渡是一个列表和描述这个列表为空消息的元素:

<transition>
 <table v-if="items.length > 0">
  <!-- ... -->
 </table>
 <p v-else>Sorry, no items found.</p>
</transition>

下面是一个例子

<style>
.fade-enter,.fade-leave-to{opacity:0;}
.fade-enter-active,.fade-leave-active{transition:opacity .5s;}
</style>
<div id="demo">
 <button @click="clear">清空数据</button> 
 <button @click="reset">重置</button>  
 <transition name="fade">
  <ul v-if="items.length > 0">
   <li v-for="item in items">{{item}}</li>
  </ul>
  <p v-else>Sorry, no items found.</p>
 </transition>
</div>
<script>
new Vue({
 el: '#demo',
 data: {
  items: ['html','css','js']
 },
 methods:{
  clear(){
   this.items.splice(0);
  },
  reset(){
   history.go();
  }
 }
})
</script>

同标签名称

如果是相同标签名的元素切换时,Vue 为了效率只会替换相同标签内部的内容

<style>
.fade-enter,.fade-leave-to{opacity:0;}
.fade-enter-active,.fade-leave-active{transition:opacity .5s;}
</style>
<div id="demo">
 <button @click="show = !show">toggle</button>  
 <transition name="fade">
  <p v-if="show">Jb51</p>
  <p v-else>JB51</p>
 </transition>
</div>
<script>
new Vue({
 el: '#demo',
 data: {
  show:true
 },
})
</script>

由下面的示例可知,两个相同的p元素切换时,无过渡效果

因此,对于具有相同标签名的元素切换的情况,需要通过 key 特性设置唯一的值来标记以让 Vue 区分它们 

<div id="demo">
 <button @click="show = !show">toggle</button>  
 <transition name="fade">
  <p v-if="show" key="trueMatch">Jb51</p>
  <p v-else key="falseMatch">JB51</p>
 </transition>
</div>

替代if

在一些场景中,可以给通过给同一个元素的 key 特性设置不同的状态来代替 v-if 和 v-else

<transition>
 <button v-if="isEditing" key="save">Save</button>
 <button v-else key="edit">Edit</button>
</transition>

上面的例子可以重写为

<transition>
 <button v-bind:key="isEditing">
  {{ isEditing "htmlcode">
<style>
.fade-enter,.fade-leave-to{opacity:0;}
.fade-enter-active,.fade-leave-active{transition:opacity .5s;}
</style>
<div id="demo">
 <button @click="isEditing = !isEditing">toggle</button>  
 <transition name="fade">
  <p v-bind:key="isEditing">
   {{ isEditing "htmlcode">
<transition>
 <button v-if="docState === 'saved'" key="saved">Edit</button>
 <button v-if="docState === 'edited'" key="edited">Save</button>
 <button v-if="docState === 'editing'" key="editing">Cancel</button>
</transition>

可以重写为

<transition>
 <button v-bind:key="docState">{{ buttonMessage }}</button>
</transition>
computed: {
 buttonMessage: function () {
  switch (this.docState) {
   case 'saved': return 'Edit'
   case 'edited': return 'Save'
   case 'editing': return 'Cancel'
  }
 }
}

下面是一个例子

<style>
.fade-enter,.fade-leave-to{opacity:0;}
.fade-enter-active,.fade-leave-active{transition:opacity .5s;}
</style>
<div id="demo">
 <button @click="change">change</button>  
 <transition name="fade">
  <p v-bind:key="docState">{{ message }}</p>
 </transition>
</div>
<script>
new Vue({
 el: '#demo',
 data: {
  index:0,
  isEditing:true,
  arr:['saved','edited','editing']
 },
 computed: {
  docState(){
   return this.arr[this.index];
  },
  message() {
   switch (this.docState) {
    case 'saved': return 'Edit'
    case 'edited': return 'Save'
    case 'editing': return 'Cancel'
   }
  }
 },
 methods:{
  change(){
   this.index = (++this.index)%3;
  }
 } 
})
</script>

过渡模式

先看下面这个例子

<style>
.fade-enter,.fade-leave-to{opacity:0;}
.fade-enter-active,.fade-leave-active{transition:opacity .5s;}
</style>
<div id="demo">  
 <transition name="fade">
  <button :key="isOn" @click="isOn = !isOn">{{ isOn "htmlcode">
<div id="demo">  
 <transition name="fade" mode="in-out">
  <button :key="isOn" @click="isOn = !isOn">{{ isOn "htmlcode">
<div id="demo">  
 <transition name="fade" mode="out-in">
  <button :key="isOn" @click="isOn = !isOn">{{ isOn "htmlcode">
<style>
#demo{position:relative;}
#demo button{position:absolute;left:40px;}
.fade-enter,.fade-leave-to{opacity:0;}
.fade-enter-active,.fade-leave-active{transition: 1s;}
</style>
<div id="demo">  
 <transition name="fade" >
  <button :key="isOn" @click="isOn = !isOn">{{ isOn "htmlcode">
<style>
#demo{position:relative;}
#demo button{position:absolute;left:40px;}
.fade-enter,.fade-leave-to{opacity:0;}
.fade-enter{transform:translateX(30px);}
.fade-leave-to{transform:translateX(-30px);} 
.fade-enter-active,.fade-leave-active{transition: 1s;}
</style>

如果设置in-out模式,将实现更酷的滑动效果

<style>
#demo{position:relative;}
#demo button{position:absolute;left:40px;}
.fade-enter,.fade-leave-to{opacity:0;}
.fade-enter{transform:translateX(30px);}
.fade-leave-to{transform:translateX(-30px);} 
.fade-enter-active,.fade-leave-active{transition: 1s;}
</style>
<div id="demo">  
 <transition name="fade" mode="in-out">
  <button :key="isOn" @click="isOn = !isOn">{{ isOn "htmlcode">
<style>
.fade-enter,.fade-leave-to{opacity:0;}
.fade-enter-active,.fade-leave-active{transition: .5s;}
</style>
<div id="example">
 <button @click="change">切换页面</button>
 <transition name="fade" mode="out-in">
  <component :is="currentView"></component>
 </transition>
</div>
<script>
new Vue({
 el: '#example',
 data:{
  index:0,
  arr:[
   {template:`<div>ComponentA</div>`},
   {template:`<div>ComponentB</div>`},
   {template:`<div>ComponentC</div>`}
  ],
 },
 computed:{
  currentView(){
    return this.arr[this.index];
  }
 },
 methods:{
  change(){
   this.index = (++this.index)%3;
  }
 }
})

更多关于Vue过渡动画的文章大家可以查看下面的相关链接

DDR爱好者之家 Design By 杰米
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DDR爱好者之家 Design By 杰米

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