深入了解Vue动态组件和异步组件

时间:2022-05-16 18:34:04

1.动态组件

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<!DOCTYPE html>
<html>
<head>
 <meta charset="utf-8">
 <style>
        #app {
            font-size: 0
        }
        .dynamic-component-demo-tab-button {
            padding: 6px 10px;
            border-top-left-radius: 3px;
            border-top-right-radius: 3px;
            border: 1px solid #ccc;
            cursor: pointer;
            margin-bottom: -1px;
            margin-right: -1px;
            background: #f0f0f0;
        }
        .dynamic-component-demo-tab-button.dynamic-component-demo-active {
            background: #e0e0e0;
        }
        .dynamic-component-demo-tab-button:hover {
            background: #e0e0e0;
        }
        .dynamic-component-demo-posts-tab {
            display: flex;                 
        }
        .dynamic-component-demo-tab {
            font-size: 1rem;
            border: 1px solid #ccc;
            padding: 10px;
        }
        .dynamic-component-demo-posts-sidebar {
            max-width: 40vw;
            margin: 0 !important;
            padding: 0 10px 0 0 !important;
            list-style-type: none;
            border-right: 1px solid #ccc;
            line-height: 1.6em;
        }
        .dynamic-component-demo-posts-sidebar li {
            white-space: nowrap;
            text-overflow: ellipsis;
            overflow: hidden;
            cursor: pointer;
        }
        .dynamic-component-demo-active {
            background: lightblue;
        }
        .dynamic-component-demo-post-container {
            padding-left: 10px;
        }
        .dynamic-component-demo-post > :first-child {
            margin-top: 0 !important;
            padding-top: 0 !important;
        }
 </style>
 <script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>
</head>
<body>
<div id="app">
    <button v-for="tab in tabs" class="dynamic-component-demo-tab-button"
        v-bind:class="{'dynamic-component-demo-active': tab === currentTab}"
        @click="currentTab = tab">{{ tab }}</button>  
    <keep-alive>
        <component v-bind:is="currentTabComponent"></component>
    </keep-alive>
</div>
<script>
 Vue.component('tab-posts', {
        data: function(){
            return {
                posts: [
                    {id: 1, title: 'Cat Ipsum', content: 'Cont wait for the storm to pass, ...'},
                    {id: 2, title: 'Hipster Ipsum', content: 'Bushwick blue bottle scenester ...'},
                    {id: 3, title: 'Cupcake Ipsum', content: 'Icing dessert souffle ...'},
                ],
                selectedPost: null
            }
        },
 template: `<div class="dynamic-component-demo-posts-tab dynamic-component-demo-tab">
                        <ul class="dynamic-component-demo-posts-sidebar">
                            <li v-for="post in posts"
                                v-bind:key="post.id"
                                v-on:click="selectedPost = post"
                                v-bind:class="{'dynamic-component-demo-active': post===selectedPost}">
                                {{ post.title }}
                            </li>
                        </ul>
                        <div class="dynamic-component-demo-post-container">
                            <div v-if="selectedPost" class="dynamic-component-demo-post">
                                <h3>{{ selectedPost.title }}</h3>
                                <div v-html="selectedPost.content"></div>
                            </div>
                            <strong v-else>
                                Click on a blog title to the left to view it.
                            </strong>
                        </div>
                    </div>`
 });
    
    Vue.component('tab-archive', {
        template: '<div class="dynamic-component-demo-tab">Archive component</div>'
    });
 
 new Vue({
 el: '#app',
        data: {
            currentTab: 'Posts',
            tabs: ['Posts', 'Archive']
        },
        computed: {
            currentTabComponent: function(){
                return 'tab-' + this.currentTab.toLowerCase()
            }
        }
 });
</script>
</body>
</html>

深入了解Vue动态组件和异步组件

在动态组件上使用keep-alive,可以在组件切换时保持组件的状态,避免了重复渲染的性能问题。

2.异步组件

Vue 允许你以一个工厂函数的方式定义你的组件,这个工厂函数会异步解析你的组件定义。

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Vue.component('async-example', function (resolve, reject) {})

这里可以回顾一下 Vue.js — 组件基础

我们使用通过webpack打包的Vue项目来介绍异步组件。

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<!-- HelloWorld.vue -->
<template>
 <div>
 <h2 class="title">{{msg}}</h2>
 </div>
</template>
 
<script>
export default {
 data () {
 return {
 msg: 'Hello Vue!'
 }
 }
}
</script>
 
<!-- Add "scoped" attribute to limit CSS to this component only -->
<style scoped>
 .title {
 padding: 5px;
 color: white;
 background: gray;
 }
</style>
<!-- App.vue -->
<template>
 <div id="app">
 <HelloWorld/>
 </div>
</template>
 
<script>
import HelloWorld from './components/HelloWorld'
 
export default {
 name: 'App',
 components: {
 HelloWorld
 }
}
</script>
 
<style>
</style>

我们把App.vue的<script>标签里面的内容改为:

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export default {
 name: 'App',
 components: {
 HelloWorld: () => import('./components/HelloWorld')
 }
}

这样就实现了App组件异步加载HelloWorld组件的功能。

我们可以实现按需加载。

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<!-- App.vue -->
<template>
 <div id="app">
 <button @click="show = true">Load Tooltip</button>
 <div v-if="show">
 <HelloWorld/>
 </div>
 </div>
</template>
 
<script>
export default {
 data: () => ({
 show: false
 }),
 components: {
 HelloWorld: () => import('./components/HelloWorld')
 }
}
</script>
 
<style>
</style>

这里的异步组件工厂函数也可以返回一个如下格式的对象:

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const AsyncComponent = () => ({
 // 需要加载的组件 (应该是一个 `Promise` 对象)
 component: import('./MyComponent.vue'),
 // 异步组件加载时使用的组件
 loading: LoadingComponent,
 // 加载失败时使用的组件
 error: ErrorComponent,
 // 展示加载时组件的延时时间。默认值是 200 (毫秒)
 delay: 200,
 // 如果提供了超时时间且组件加载也超时了,
 // 则使用加载失败时使用的组件。默认值是:`Infinity`
 timeout: 3000
})

参考:

动态组件 & 异步组件 — Vue.js

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原文链接:https://www.cnblogs.com/gzhjj/p/11792692.html