1.兄弟A先给父元素 父元素再给子组件B (vue2的思路)
A组件

<template> 
    <div style="width：300px;height:200px;background:blue"> 
        <button @click="add">A派发事件</button> 
    </div>
</template>
<script setup lang="ts">
import { defineEmits } from "vue" 
// emit
const emit=defineEmits(['onclick']);
let  flag=false;
const add=()=>{
    flag=!flag;
  emit('onclick',flag)
}
 
</script>

<style scoped>

</style>

父组件

<template>
  <div>
    <A  @onclick="onclick"></A>
    //在把A组件传输的值传给组件B
    <B :flag='flag'></B>
    A组件传输的值{{flag}}
  </div>
</template>

<script setup lang="ts">
import  {ref} from 'vue'
import  A from './components/fuzi/A.vue'
import  B from './components/fuzi/B.vue'
let  flag=ref(null);
const onclick=(params:boolean)=>{
//拿到传输的值赋给变量flag
flag.value=params;

}

</script>

<style scoped>

</style>

组件B

<template>
    <div style="width：300px;height:200px;background:red"> 
      B组件接受的值：  {{flag}}
    </div>
</template>

<script setup lang="ts">
import { defineProps} from "vue";
import  mitts  from '../../util/bus.js';
 
type Props={
    flag:boolean
}
defineProps<Props>();
</script>

<style scoped>

</style>

2.兄弟组件直接传输 （局部引入）

npm install mitt

定义一个bus.js

import  mitt  from 'mitt';
const  mitts=mitt();
export default mitts;

组件A：

<template> 
    <div style="width：300px;height:200px;background:blue">
        <button @click="child">兄弟传参</button>
    </div>
</template>
<script setup lang="ts">
import  mitts  from '../../util/bus.js'; 
let  flag=false;
const  child=()=>{
    mitts.emit('event',flag)
}
</script>

<style scoped>

</style>

组件B：

<template>
    <div style="width：300px;height:200px;background:red"> 
      B组件接受的值：  {{flag}}
    </div>
</template>

<script setup lang="ts">
import {onBeforeMount,ref} from "vue";
import  mitts  from '../../util/bus.js';
 let  flag=ref(null);
onBeforeMount(()=>{
  mitts.on('event',(e:boolean)=>{
      flag.value=e
  })
})
</script>

<style scoped>

</style>

3.兄弟传参（全局引入）

npm install mitt

main.ts

import { createApp } from 'vue'
import './style.css'
import App from './App.vue'
import mitt from 'mitt'
const  app=createApp(App);
app.config.globalProperties.$mitt=mitt();
app.mount('#app')

组件A

<template> 
    <div style="width：300px;height:200px;background:blue"> 
        <button @click="child">兄弟传参</button>
    </div>
</template>
<script setup lang="ts">
import {  getCurrentInstance,ComponentInternalInstance  } from "vue" 
const {appContext }=getCurrentInstance() as ComponentInternalInstance
let  flag=false;
 const  child=()=>{
    flag=!flag; 
    appContext.config.globalProperties.$mitt.emit('event',flag) 
}
</script>

<style scoped>

</style>

兄弟B

<template>
    <div style="width：300px;height:200px;background:red"> 
     {{flag}}
    </div>
</template>

<script setup lang="ts">
import { ref ,onBeforeMount,getCurrentInstance,ComponentInternalInstance} from "vue";
type Props={
    flag:boolean
} 
const flag<Props>=ref(null);
const {appContext}=getCurrentInstance() as ComponentInternalInstance 
onBeforeMount(()=>{
    appContext.config.globalProperties.$mitt.on('event',(e:boolean)=>{ 
      flag.value=e;

  })
 
</script>

<style scoped>

</style>