【Vue3基础】组件保持存活、异步加载组件

一、组件保持存活

1、需求描述

点击按钮跳转到其他组件后，原组件不会被销毁

2、知识整理

1）组件生命周期

创建期：beforeCreate、created

挂载期：beforeMount、mounted

更新期：beforeUpdate、updated

销毁期：beforeUnmount、unmounted

2)保持组件存活keep-alive

 <keep-alive><component :is="tabComponent"></component></keep-alive>

3）实现异步组件加载

defineAsyncComponent

3、代码演示

1）文件

 2）App.vue文件

<template><keep-alive><component :is="tabComponent"></component></keep-alive><button @click="changeHandle">切换按钮</button>
</template>
<script>
import ComponentA from "./components/ComponentA.vue";
import ComponentB from "./components/ComponentB.vue";
export default{data(){return{tabComponent:"ComponentA"}},components: { ComponentA,ComponentB},methods:{changeHandle(){this.tabComponent=this.tabComponent=="ComponentA"?"ComponentB":"ComponentA"}}
}
</script>

3）ComponentA.vue文件

<template><h3>ComponentA</h3><p>{{ message }}</p><button @click="updateHandle">更新数据</button>
</template>
<script>
export default{data(){return {message:"老数据"}},beforeUnmount(){console.log("组件卸载之前");},unmounted(){console.log("组件卸载之后");},methods:{updateHandle(){this.message="新数据"}}
}
</script>

4）ComponentB.vue文件

<template><h3>ComponentB</h3>
</template>
<script></script>

5、效果展示

1）打开浏览器

 2）点击“更新数据”按钮，“老数据”将变为“新数据”

3）点击“切换按钮”，跳转到组件B中

4）再点击“切换按钮”，跳转回组件A，仍保持显示“新数据”

>>>

二、 异步加载组件

1、关键代码 App.vue文件

<script>
import ComponentA from "./components/ComponentA.vue";
//import ComponentB from "./components/ComponentB.vue";
//异步加载B组件
import { defineAsyncComponent } from "vue";
const ComponentB=defineAsyncComponent(()=>import("./components/ComponentB.vue"))

2、效果展示

1）登录浏览器 ，B组件未被加载

2）点击切换按钮后，才加载B组件

>

三、学习链接

https://www.bilibili.com/video/BV1Rs4y127j8?p=37&spm_id_from=pageDriver&vd_source=841fee104972680a6cac4dbdbf144b50