An article briefly analyzing the problem of value transfer between parent and child components in Vue

How to pass values ​​between vue parent and child components? The following article will take you through the value transfer issues of parent components and child components in Vue. I hope it will be helpful to you!

Preface: In some pages, there is not just a pure vue file. Vue pays attention to component development, but generally interactive events will definitely occur. I learned about this today Pass value, hereby record it.

1. Parent component passes value to child component

Parent component passes value to child component and will use: Prop, generally we need to make relevant declarations in sub-components, as shown below:

The sub-component is HellowWorld.vue

<script>export default {
  name: &#39;HelloWorld&#39;,
  //接收的变量
  props: {
  //声明相关的类型
    msg: String,
    count:Number,
    options:[]
  },
  data(){
    return{

    }
  },
  methods:{
  }}</script>

In the parent component App.vue

<template>
  <div>
    <!-- msg为字符串类型，count为数字，options为数组 -->
    <helloworld></helloworld>
  </div></template><script>//引入组件import HelloWorld from &#39;./components/HelloWorld.vue&#39;export default {
  name: &#39;App&#39;,
  components: {
    HelloWorld  },
  data(){
    return{
      count:0,
      options:[],
    }
  },
  methods:{
  }}</script>

Then the effect on the page is:

Of course we can also write Some events are used for dynamic data interaction, for example:

2. Child component passes value to parent component

$emit is used when passing values ​​to subcomponents. It is worth noting that the method used when passing values ​​to subcomponents must have the same name as the method listened in the parent component, which is listenToChild in the example. [Related recommendations: vuejs video tutorial, web front-end development]

Helloworld.vue sub-component:

<template>
  <div>
    <!-- 文字信息 -->
    <h1>{{ msg }}</h1>
    <!-- 数字信息 -->
    <h2>{{count}}</h2>
    <!-- 渲染数组信息 -->
    <ul>
      <li>{{item}}</li>
    </ul>
    <!-- 进行传值 -->
    <button>点击</button>
  </div></template><script>export default {
  name: &#39;HelloWorld&#39;,
  props: {
    msg: String,
    count:Number,
    options:[]
  },
  data(){
    return{

    }
  },
  methods:{
    SendMsg(){
      // listenToChild  注意
      this.$emit(&#39;listenToChild&#39;,this.options)
    }
  }}</script><!-- Add "scoped" attribute to limit CSS to this component only --><style>h3 {
  margin: 40px 0 0;}ul {
  list-style-type: none;
  padding: 0;}/* li {
  display: inline-block;
  margin: 0 10px;
} */a {
  color: #42b983;}</style>

App.vue parent component:

<template>
  <div>
    <img  alt="An article briefly analyzing the problem of value transfer between parent and child components in Vue" >
    <!-- listenToChild 为子组件传来的方法 -->
    <helloworld></helloworld>
    <button>+</button>
    <button>置零</button>
    <button>-</button>
    <ul>
      <li>{{index}}，{{item}}</li>
    </ul>
  </div></template><script>import HelloWorld from &#39;./components/HelloWorld.vue&#39;export default {
  name: &#39;App&#39;,
  components: {
    HelloWorld  },
  data(){
    return{
      // 要传去子组件的参数
      count:0,
      options:[],
      // 子组件传来的参数
      data:[]
    }
  },
  methods:{
    Add(){
      this.count=Number(this.count)+1
      this.options.push(&#39;添加一次，当前数值为：&#39;+this.count)
    },
    Sub(){
     
      if(this.count<=0){
        this.options.push(&#39;当前数值不能变化了&#39;+this.count)
      }else{
        this.count=Number(this.count)-1
       this.options.pop()
      }
       
    },
    show(data){
      console.log(data)
      this.data=data    },
    restart(){
      this.count=0
      this.options=[]
    }
  }}</script><style>#app {
  font-family: Avenir, Helvetica, Arial, sans-serif;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-align: center;
  color: #2c3e50;
  margin-top: 60px;}button{
  margin: 20px;}ul {
  list-style-type: none;
  padding: 0;}</style>

Effect:

(Learning video sharing: vuejs introductory tutorial, Basic Programming Video)

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