vue3组件通信的方式总结及实例用法

vue3组件通信方式为以下几种

• props
• $emit
• $expose / ref
• $attrs
• v-model
• provide / inject
• Vuex
• mitt

props

<child :msg2=\"msg2\" />
<script setup>
    const props = defineProps({
        // 写法一
        msg2:String
        // 写法二
        msg2:{
            type:String,
            default:\'\'
        }
    })
    console.log(props) // {msg2:\'这是传级子组件的信息2\'}
</script>

$emit

//Child.vue
<template>
    // 写法一
    <div @click=\"emit(\'myclick\')\">按钮</div>
    // 写法二
    <div @click=\"handleClick\">按钮</div>
</template>
<script setup>
    // 方法一
    const emit = defineEmits([\'myClick\'],[\'myClick2\'])
    // 方法二
    const handleClick = () => {
        emit(\'myClick\',\'这是发送给父组件的信息\');
     }
      
     // 方法二 不适用于vue3.2，使用的useContext()已经舍弃
     import { useContext } from \'vue\'
     const { emit } = useContext()
     const handleClick = () => { 
      emit(\'myClick\',\'这是发送给父组件的信息\'   
     }
</script>
 
// Parent.vue响应
<template>
    <child @myClick=\"onMyClick\"></child>
</template>
<script setup>
    import child from \"./child.vue\"
    import onMychilk = (msg) => {
        console.log(msg) // 父组件收到的信息 
    }
</script>

expose / ref

父组件获取子组件的属性或者调用子组件方法

<script setup>
    // 方法一：useContext() vue3.2 之后已经舍弃
    import { useContext } from \'vue\'
    const ctx = useContext()
    // 对外暴露属性方法等都可以
    ctx.expose({
        childName: \'这是子组建的属性\',
        someMethod(){
        console.log(\'这是子组件的方法\')
        }
    })
</script>
 
// Parent.vue 注意 ref=\"comp\"
<template>
    <child ref=\"comp\"></child>
    <button @click=\"handleClick\">按钮</button>
</template>
<script>
    import child from \'./child.vue\'
    import { ref } from \'vue\' 
    const comp = ref(null)
    const handleClick = () => {
        console.log(comp.value.childName)
        comp.value.someMethod() // 调用子组件对外暴露的方法
    }
</script>

attts

attrs:包含父作用域除class和style除外的非props属性集合

// 父组件
<child :msg1=\"msg1\" :msg2=\"msg2\" title=\"3333\"></child>
<script setup>
    import child from \'./child.vue\'
    import { ref,reactive } from \'vue
    const msg1 = ref(\'111\')
    const msg2 = ref(\'222\')
</script>
 
// 子组件
<script setup>
    import { defineProps,useContext,useAttars } from \'vue\'
    const props = defineProps({
        msg1: String
    })
     
    // 方法1
    const ctx = useContext()
    console.log(ctx.attars) // {msg2:\'222\',title:\'333\'}
     
    // 方法2 
    const attrs = useAttars()
    console.log(attars)  // {msg2:\'2222\',title:\'3333\'}
</script>

v-model

可以支持多个数据双向绑定

<child v-model:key=\"key\" v-modle:value=\"value\" />
<script>
    import child from \'./child.vue\'
    import { ref,reactive } from \'vue\'
    const key = ref(\'111\')
    const value = ref(\'222\')
</script>
 
//子组件
<template>
   <button @click=\"handleClick\"></button>
</template>
<script setup>
    // 方法一  v3.2 已被移除
    import { useContext } from \'vue\'
    const { emit } = useContext()
     
    // 方法二
    import { defineEmits } from \'vue\'
    const emit = defineEmits([\'key\',\'value\'])
     
    //用法
    const handleClick = () => {
        emit(\'update:key\',\'新的key\')
        emit(\'update:value\',\'新的value\')
    }
</script>

provide / inject

provide/inject为依赖注入 provide：可以让我们指定想要提供给后代组件的数据 inject:在任何后代组件中接受想要添加在这个组件上的数据，不管组件嵌套多深都可以直接拿来用

// 父组件
<script setup>
    import { provide } from \'vue\'
    const name = provide(\'name\')
    console.log(\'name\',\'沐华\')
</script>
//子组件
<script setup>
    import { inject } from \'vue\'
    const name = inject(\'name\')
    console.log(name) //木华
</script>

Vuex

//store/index.js
import { createStore } from \'vuex\'
export default createStore({
    state:{count:1},
    getters:{
        getCount:state=>state.count
    },
    mutations:{
        add(state){
            state.count++
        }
    }
   })
 // main.js
 import { createApp } from \'vue\'
 import APP from \'./App.vue\'
 import store from \'./store\'
 createApp(APP).use(store).mount(\"#app\")
  
 // 直接使用
 <template>
     <div>
         {{ $store.state.count }}
     </div>
     <button @click=\"$store.commit(\'add\')\">
     </button>
 </template>
  
 // 获取
 <script setup>
     import { useStore,computed } from \'vuex\'
     const store = useStore()
     console.log(store.state.count)
      
     const count = computed (()=>store.state.count)
     console.log(count)
 </script>

mitt

Vue3中已经没有了EventBus跨组件通信，替代方案mitt.js，但原理方式EventBus是一样的
安装方式 npm i mitt -S

封装

mitt.js
import mitt from \'mitt\'
const mitt = mitt()
export default mitt

组件之间使用

// 组件A 
<script setup>
    import mitt from \'./mitt\'
    const handleClick = () => {
        mitt.emit(\'handleChange\')
    }
</script>
// 组件B 
<script setup>
import mitt from \'./mitt\'
import { onUnmounted } from \'vue\'
const someMethod = () => {...}
mitt.on(\'handleChange\',someMethod)
onUnmounted(()=>{
    mitt.off(\'handleChange\',someMethod)
})
</script>