Vue--keep-alive
IT利刃出鞘 人气:0简介
说明
本文用示例介绍Vue的keep-alive的用法。
keep-alive标签主要用于保留组件状态或避免重新渲染。
官网网址
https://v2.cn.vuejs.org/v2/api/#keep-alive
相关网址
公共代码
路由(router/index.js)
import Vue from 'vue' import VueRouter from 'vue-router' import Parent from '../components/Parent' Vue.use(VueRouter) const routes = [ { path: '/', name: 'Parent', component: Parent } ] const router = new VueRouter({ routes }) export default router
生命周期mixin(mixins/LifeCycle.js)
下边的两个页面组件都要打印生命周期,所以我把它抽出作为mixin。
export default { computed: { name () { return this.$options.name } }, created () { console.log('created ==> ' + this.name) }, activated () { console.log('activated ==> ' + this.name) }, deactivated () { console.log('deactivated ==> ' + this.name) }, destroyed () { console.log('destroyed ==> ' + this.name) } }
子页面组件
components/CompA.vue
<template> <div class="outer"> <div> 这是CompA </div> </div> </template> <script> import LifeCycle from '../mixins/LifeCycle' export default { name: 'CompA', mixins: [LifeCycle] } </script> <style scoped> .outer { margin: 20px; border: 2px solid blue; padding: 20px; } </style>
components/CompB.vue
<template> <div class="outer"> 这是CompB </div> </template> <script> import LifeCycle from '../mixins/LifeCycle' export default { name: 'CompB', mixins: [LifeCycle] } </script> <style scoped> .outer { margin: 20px; border: 2px solid blue; padding: 20px; } </style>
动态组件实例
不加keep-alive
代码
components/Parent.vue
<template> <div class="outer"> <div> 这是Parent </div> <br> <button @click="useCompA">切换到CompA</button> | <button @click="useCompB">切换到CompB</button> <component :is="componentName"></component> </div> </template> <script> import CompA from './CompA' import CompB from './CompB' export default { name: 'Parent', components: { CompA, CompB }, data () { return { componentName: '' } }, methods: { useCompA () { this.componentName = 'CompA' }, useCompB () { this.componentName = 'CompB' } } } </script> <style scoped> .outer { margin: 20px; border: 2px solid red; padding: 20px; } </style>
测试
访问:http://localhost:8080/#/
可以发现:进入组件时调用created;离开组件时调用destroyed。
加keep-alive
代码
component/Parent.vue
将动态组件用keep-alive标签包起来。
<template> <div class="outer"> <div> 这是Parent </div> <br> <button @click="useCompA">切换到CompA</button> | <button @click="useCompB">切换到CompB</button> <keep-alive> <component :is="componentName"></component> </keep-alive> </div> </template> <script> import CompA from './CompA' import CompB from './CompB' export default { name: 'Parent', components: { CompA, CompB }, data () { return { componentName: '' } }, methods: { useCompA () { this.componentName = 'CompA' }, useCompB () { this.componentName = 'CompB' } } } </script> <style scoped> .outer { margin: 20px; border: 2px solid red; padding: 20px; } </style>
测试
访问:http://localhost:8080/#/
可以发现:进入组件时调用created、activated;离开组件时调用deactivated(不调用destroyed)。
router-view实例
不加keep-alive
代码
修改路由设置(router/index.js)
import Vue from 'vue' import VueRouter from 'vue-router' import Parent from '../components/Parent' import CompA from '../components/CompA' import CompB from '../components/CompB' Vue.use(VueRouter) const routes = [ { path: '/', name: 'Parent', component: Parent }, { path: '/compA', name: 'CompA', component: CompA }, { path: '/compB', name: 'CompB', component: CompB } ] const router = new VueRouter({ routes }) export default router
修改入口组件(components/Parent.vue)
<template> <div class="outer"> <div> 这是Parent </div> <br> <router-link :to="{name: 'CompA'}">跳转到CompA</router-link> | <router-link :to="{name: 'CompB'}">跳转到CompB</router-link> <router-view></router-view> </div> </template> <script> export default { name: 'Parent' } </script> <style scoped> .outer { margin: 20px; border: 2px solid red; padding: 20px; } </style>
测试
访问:http://localhost:8080/#/
可以发现:进入路由组件时调用created;离开路由组件时调用destroyed。
加keep-alive(加到App.vue里)
修改App.vue
将router-view标签包裹在keep-alive标签里。
<template> <div id="app"> <div id="nav"> <router-link to="/">Home</router-link> | <router-link to="/about">About</router-link> </div> <!-- 原来写法 --> <!-- <router-view/> --> <keep-alive> <router-view/> </keep-alive> </div> </template> <style> <!-- 省略 --> </style>
测试
访问:http://localhost:8080/#/
可以发现:进入组件时调用created、activated;离开组件时调用deactivated(不调用destroyed)。
加keep-alive(加到Parent.vue里)
说明
需要做如下两步:
- Parent.vue:将router-view包裹在keep-alive里边
- 将CompA和CompB的路由作为Parent的嵌套路由(Children)
如果只修改Parent.vue,将router-view包裹在keep-alive里边,这样是没用的,跟没有加keep-alive效果一样。
代码
修改components/Parent.vue
<template> <div class="outer"> <div> 这是Parent </div> <br> <router-link :to="{name: 'CompA'}">跳转到CompA</router-link> | <router-link :to="{name: 'CompB'}">跳转到CompB</router-link> <keep-alive> <router-view></router-view> </keep-alive> </div> </template> <script> export default { name: 'Parent' } </script> <style scoped> .outer { margin: 20px; border: 2px solid red; padding: 20px; } </style>
修改路由(router/index.js)
import Vue from 'vue' import VueRouter from 'vue-router' import Parent from '../components/Parent' import CompA from '../components/CompA' import CompB from '../components/CompB' Vue.use(VueRouter) const routes = [ { path: '/', name: 'Parent', component: Parent, children: [ { path: '/compA', name: 'CompA', component: CompA }, { path: '/compB', name: 'CompB', component: CompB } ] } ] const router = new VueRouter({ routes }) export default router
测试
访问:http://localhost:8080/#/
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