keep-alive 传送门
<keep-alive> 包裹动态组件时，会缓存不活动的组件实例，而不是销毁它们。和 <transition> 相似，<keep-alive> 是一个抽象组件：它自身不会渲染一个 DOM 元素，也不会出现在父组件链中。
当组件在 <keep-alive> 内被切换，它的 activated 和 deactivated 这两个生命周期钩子函数将会被对应执行。
主要用于保留组件状态或避免重新渲染
include - 字符串或正则表达式。只有名称匹配的组件会被缓存
exclude - 字符串或正则表达式。任何名称匹配的组件都不会被缓存
Learn
一、不使用<keep-alive>包裹动态组件
二、使用<keep-alive>包裹动态组件
目录结构
一、不使用<keep-alive>包裹动态组件
此时组件A、B、C组件中的数会一直随机0~100且不重复
<div id="GaryId">
<button @click="selectedName = 'my-component-a'"> a </button>
<button @click="selectedName = 'my-component-b'"> b </button>
<button @click="selectedName = 'my-component-c'"> c </button> <component :is="selectedName"></component> </div>
"my-component-a":{
template:"<h1>A :{{num}}</h1>",
data(){
return{
num:Math.ceil(Math.random()*100)
}
}
},
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Gary</title>
</head>
<body>
<div id="GaryId">
<button @click="selectedName = 'my-component-a'"> a </button>
<button @click="selectedName = 'my-component-b'"> b </button>
<button @click="selectedName = 'my-component-c'"> c </button> <component :is="selectedName"></component> </div>
</body> <script type="text/javascript" src="../js/vue.js" ></script>
<script type="text/javascript"> new Vue({
data:{
selectedName:'my-component-a'
},
components:{
"my-component-a":{
template:"<h1>A :{{num}}</h1>",
data(){
return{
num:Math.ceil(Math.random()*100)
}
}
},
"my-component-b":{
template:"<h1>B :{{num}}</h1>",
data(){
return{
num:Math.ceil(Math.random()*100)
}
}
},
"my-component-c":{
template:"<h1>C :{{num}}</h1>",
data(){
return{
num:Math.ceil(Math.random()*100)
}
}
}
}
}).$mount("#GaryId");
</script>
</html>
Gary_dynamic_component.html
二、使用<keep-alive>包裹动态组件
此时组件A、B、C组件中的数会第一次会随机出现，随后保存到缓存中，第二次再点击的时候它们会读取缓存中的数
<div id="GaryId">
<button @click="selectedName = 'my-component-a'"> a </button>
<button @click="selectedName = 'my-component-b'"> b </button>
<button @click="selectedName = 'my-component-c'"> c </button> <keep-alive>
<component :is="selectedName"></component>
</keep-alive>
</div>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Gary</title>
</head>
<body>
<div id="GaryId">
<button @click="selectedName = 'my-component-a'"> a </button>
<button @click="selectedName = 'my-component-b'"> b </button>
<button @click="selectedName = 'my-component-c'"> c </button> <keep-alive>
<component :is="selectedName"></component>
</keep-alive>
</div>
</body> <script type="text/javascript" src="../js/vue.js" ></script>
<script type="text/javascript"> new Vue({
data:{
selectedName:'my-component-a'
},
components:{
"my-component-a":{
template:"<h1>A :{{num}}</h1>",
data(){
return{
num:Math.ceil(Math.random()*100)
}
}
},
"my-component-b":{
template:"<h1>B :{{num}}</h1>",
data(){
return{
num:Math.ceil(Math.random()*100)
}
}
},
"my-component-c":{
template:"<h1>C :{{num}}</h1>",
data(){
return{
num:Math.ceil(Math.random()*100)
}
}
}
}
}).$mount("#GaryId");
</script>
</html>
Gary_dynamic_component.html
当只想缓存A组件
<keep-alive include="my-component-a">
<component :is="selectedName"></component>
</keep-alive>
当想缓存A组件和B组件时候
<keep-alive :include="['my-component-a','my-component-b']">
<component :is="selectedName"></component>
</keep-alive>
排除缓存A组件和B组件的时候
<keep-alive :exclude="['my-component-a','my-component-b']">
<component :is="selectedName"></component>
</keep-alive>