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1. 借助父组件传参

A 组件派发一个事件，修改 flag 的值，先传递给父组件，然后由父组件传递给 B 组件。

缺点：必须由 App.vue 处理中间逻辑。

A.vue

<template><div class="A"><h1>A组件</h1><button @click="emitB">派发一个事件</button></div>
</template><script setup lang="ts">
const emit = defineEmits(['on-click'])
let flag = false
const emitB = () => {flag = !flagemit('on-click', flag)
}
</script><style scoped>
.A {width: 200px;height: 200px;color: #fff;background: blue;
}
</style>

App.vue

<template><div><A @on-click="getFlag"></A><B :flag="Flag"></B></div>
</template><script setup lang="ts">
import A from './components/A.vue';
import B from './components/B.vue';
import { ref } from 'vue'
let Flag = ref<boolean>(false)
const getFlag = (flag:boolean) => {Flag.value = flag
}
</script><style scoped></style>

B.vue

<template><div class="B"><h1>B组件</h1>{{ flag }}</div>
</template><script setup lang="ts">
type Props = {flag: boolean
}
defineProps<Props>()</script><style lang="scss" scoped>
.B{width: 200px;height: 200px;color: #fff;background: red;
}
</style>

2. Event Bus

Event Bus（事件总线）是一种在Vue中实现组件间通信的模式。它使用了Vue实例作为中央的事件中心，允许任何组件注册监听器并触发事件。通过事件总线，兄弟组件之间可以进行解耦合的通信。

原理是利用了 JavaScript 设计模式的发布-订阅（Publish-Subscribe Pattern），然后由事件调度中心（Event Loop）进行处理。

// Bus.tstype BusClass = {emit: (name: string) => voidon: (name: string, callback: Function) => void
}type PramsKey = string | number | symboltype List = {[key: PramsKey]: Array<Function>
}class Bus implements BusClass {list: Listconstructor() {this.list = {}}emit(name: string, ...args:Array<any>): void {let eventName: Array<Function> = this.list[name]eventName.forEach(fn =>{fn.apply(this, args)})}on(name: string, callback: Function): void {let fn:Array<Function> = this.list[name] || []fn.push(callback)this.list[name] = fn}
}
export default new Bus()

<!-- A.vue -->
<template><div><h1>A组件</h1><button @click="emitB">派发一个事件</button><hr></div>
</template><script setup lang="ts">
import Bus from '../Bus'
let flag = false
const emitB = () =>{flag = !flagBus.emit('on-click', flag)
}
</script><style scoped></style>

<!-- B.vue -->
<template><div><h1>B组件</h1>{{ Flag }}</div>
</template><script setup lang="ts">
import Bus from '../Bus'
import { ref } from 'vue'
let Flag = ref(false)
Bus.on('on-click', (flag:boolean)=> {Flag.value = flag
})</script><style scoped></style>

<!-- App.vue -->
<template><div><A></A><B></B></div>
</template><script setup lang="ts">
import A from './components/A.vue'
import B from './components/B.vue'</script><style scoped></style>