vue- study notes - the component (basic component)

This chapter includes the components: multiplexing basic use, components, tissue components, assembly prop parameter passing, switching, characteristic IS, slot, event binding, v-model

Basic use:

Component is Vue examples reusable , and has a name

Examples Vue component is multiplexed, and so they are new Vue receiving the same options , for example data, computed, watch, methods and lifecycle hooks and the like. The only exception is like el this root instance-specific options.

// 定义一个名为 button-counter 的新组件
Vue.component('button-counter', {
  data: function () {
    return {
      count: 0
    }
  },
  template: '<button v-on:click="count++">You clicked me {{ count }} times.</button>'
})

<div id="components-demo">
  <button-counter></button-counter>
</div>

new Vue({ el: '#components-demo' })

Reusable component

Each component has a separate counter

data: it must be a constructor: If the object is written, I run this error

data: function () {
  return {
    count: 0
  }
}

Organizational components

In order to use the template, these components must be registered in order to be able to identify Vue

Component global registration

1: can be used after it has been registered with any (by the new VueVue root instance) newly created,

2: template for all of its component sub-assemblies tree

Transmitting data to the sub-assembly by Prop

Do not pass data to the component, the component does not make sense!

A default component can have any number of prop, any value can be passed to any prop

Vue.component('blog-post', {
  props: ['title'],
  template: '<h3>{{ title }}</h3>'
})

<blog-post title="My journey with Vue"></blog-post>
<blog-post title="Blogging with Vue"></blog-post>
<blog-post title="Why Vue is so fun"></blog-post>

v-for example

new Vue({
  el: '#blog-post-demo',
  data: {
    posts: [
      { id: 1, title: 'My journey with Vue' },
      { id: 2, title: 'Blogging with Vue' },
      { id: 3, title: 'Why Vue is so fun' }
    ]
  }
})

<blog-post
  v-for="post in posts"
  v-bind:key="post.id"
  v-bind:title="post.title"
></blog-post>

A single root element (root element component must have a similar command angularjs)

A post object may be transmitted to the props; v-for key must ha

The following code uses a template string ES6 the concept, you do not want to compile Babel or TypeScript like tools, please use the escape character line change

Vue.component('blog-post', {
  props: ['post'],
  template: `
    <div class="blog-post">
      <h3>{{ post.title }}</h3>
      <div v-html="post.content"></div>
    </div>
  `
})

Monitor sub-component events

Parent component:

<blog-post
  ...
  v-on:enlarge-text="postFontSize += 0.1"
></blog-post>

Subassembly:

<button v-on:click="$emit('enlarge-text')">
  Enlarge text
</button>

使用事件抛出一个值:$emit第二个参数

子组件

<button v-on:click="$emit('enlarge-text', 0.1)">
  Enlarge text
</button>

父组件通过:$event监听获取

<blog-post
  ...
  v-on:enlarge-text="postFontSize += $event"
></blog-post>


//父组件是一个事件处理函数
<blog-post ... v-on:enlarge-text="onEnlargeText" ></blog-post>

methods: { 
  onEnlargeText: function (enlargeAmount) { 
     this.postFontSize += enlargeAmount 
    } 
}

在组件上使用 `v-model`

<input v-model="searchText">

等价于

<input
  v-bind:value="searchText"
  v-on:input="searchText = $event.target.value"
>

用在组件上会是这个样子

<custom-input
  v-bind:value="searchText"
  v-on:input="searchText = $event"
></custom-input>

将其 value 特性绑定到一个名叫 value 的 prop 上
在其 input 事件被触发时，将新的值通过自定义的 input 事件抛出

写成代码是这样子
Vue.component('custom-input', {
  props: ['value'],
  template: `
    <input
      v-bind:value="value"
      v-on:input="$emit('input', $event.target.value)"
    >
  `
})

使用时候这个样子

<custom-input v-model="searchText"></custom-input>

通过插槽分发内容

Vue.component('alert-box', {
  template: `
    <div class="demo-alert-box">
      <strong>Error!</strong>
      <slot></slot>
    </div>
  `
})

html页面:

<alert-box>
  Something bad happened.
</alert-box>

效果:

动态组件(组件切换)

Vue 的 <component> 元素加一个特殊的 is 特性来实现：

其中currentTabComponent可以取值

已注册组件的名字，或
一个组件的选项对象

<!-- 组件会在 `currentTabComponent` 改变时改变 -->
<component v-bind:is="currentTabComponent"></component>

解析 DOM 模板时的注意事项(is问题)

有些 HTML 元素，诸如 <ul>、<ol>、<table> 和 <select>，对于哪些元素可以出现在其内部是有严格限制的。而有些元素，诸如 <li>、<tr> 和 <option>，只能出现在其它某些特定的元素内部。

错误的用法

<table>
  <blog-post-row></blog-post-row>
</table>

正确的用法

<table>
  <tr is="blog-post-row"></tr>
</table>

需要注意的是如果我们从以下来源使用模板的话，这条限制是不存在的：

字符串 (例如：template: '...')
单文件组件 (.vue)
<script type="text/x-template">

下面是单文件组件和template