vue 父子组件通信

vue 父子组件通信，如下图

父组件通过 props 向下传递数据给子组件，子组件通过 events 给父组件发送消息

子组件的 props 选项能够接收来自父组件数据，但由于 props 是单向绑定的，所以只能是父组件向子组件传递，不能子组件向父组件传递

子组件通过触发事件来通知父组件改变数据

代码示例如下

首先定义父组件 parent-component.vue

<template>
    <div>
        <div>
            <label>父组件</label>
        </div>
  
        <div>
            <input type="text" v-model="message" placeholder="请输入内容">
            <button class="size" @click="show">显示</button>    
        </div>
    </div>
</template>
  
<script>
  
export default {
    data (){
        return {
            message: ''        
        }
    },
    methods: {
        show(){
            alert(this.message)
        }
    }
     
}
</script>
  
<style>
.size {
   width: 200px
}
</style>

　　其次定义子组件 child-component.vue

<template>
    <div>
        <div>
            <label>子组件</label>
        </div>
        <div>
             <span>来自父组件的消息:{{msg}}</span>
        </div>
    </div>
</template>
  
<script>
export default {
    props: ['msg']
}
</script>

父组件向子组件传递数据

定义完成后，在父组件中引入子组件

<template>
    <div>
        <div>
            <label>父组件</label>
        </div>
  
        <div>
            <input type="text" v-model="message" placeholder="请输入内容">
            <button class="size" @click="show">显示</button>    
        </div>
        <ChildComponent :msg="message"></ChildComponent>
    </div>
</template>
  
<script>
import ChildComponent from './child-component'
export default {
    components:{
        ChildComponent
    },
    data (){
        return {
            message: ''        
        }
    },
    methods: {
        show(){
            alert(this.message)
        }
    }
     
}
</script>
  
<style>
.size {
   width: 200px
}
</style>

　　运行后效果如下图，实现了父组件向子组件的单向数据传递

子组件向父组件传递数据

修改子组件代码如下

<template>
    <div>
        <div>
            <label>子组件</label>
        </div>
        <div>
             <span>来自父组件的消息:{{msg}}</span>
  
             <br>
             <input type="text" v-model="text">
             <button @click="sendMessage">向父组件发送消息</button>
        </div>
    </div>
</template>
  
<script>
export default {
    props: ['msg'],
    data (){
        return {
            text: ''
        }
    },
    methods: {
        sendMessage(){
            this.$emit('receiveMessage', this.text)
        }
    }
}
</script>

　　修改父组件代码如下

<template>
    <div>
        <div>
            <label>父组件</label>
        </div>
  
        <div>
            <input type="text" v-model="message" placeholder="请输入内容">
            <button class="size" @click="show">显示</button>    
        </div>
        <ChildComponent :msg="message" @receiveMessage='receiveMessage'></ChildComponent>
    </div>
</template>
  
<script>
import ChildComponent from './child-component'
export default {
    components:{
        ChildComponent
    },
    data (){
        return {
            message: ''        
        }
    },
    methods: {
        show(){
            alert(this.message)
        },
        receiveMessage(message){
            console.log(message)
        }
    }   
}
</script>
  
<style>
.size {
   width: 200px
}
</style>