Vue 3 中使用 Mitt 事件总线方案详解

npm install mitt
# 或
yarn add mitt
# 或
pnpm add mitt

// src/utils/eventBus.ts
import mitt from 'mitt'
type Events = {
  // 定义事件类型
  'user-login': { userId: string; username: string }
  'user-logout': void
  'notification': string
  'update-count': number
  // 使用通配符监听所有事件
  '*': { type: string; payload?: any }
}
const eventBus = mitt<Events>()
export default eventBus

<!-- ComponentA.vue -->
<script setup lang="ts">
import { onUnmounted } from 'vue'
import eventBus from '@/utils/eventBus'
// 发射事件
const emitLogin = () => {
  eventBus.emit('user-login', {
    userId: '123',
    username: '张三'
  })
}
// 监听事件
eventBus.on('notification', (message) => {
  console.log('收到通知:', message)
})
// 监听所有事件
eventBus.on('*', (type, payload) => {
  console.log(`事件类型: ${type}`, payload)
})
// 组件卸载时取消监听
onUnmounted(() => {
  eventBus.off('notification')
  // 或者取消所有监听
  // eventBus.all.clear()
})
</script>

<!-- Header.vue -->
<script setup lang="ts">
import eventBus from '@/utils/eventBus'
const logout = () => {
  eventBus.emit('user-logout')
}
const sendNotification = () => {
  eventBus.emit('notification', '新消息！')
}
</script>

<!-- Sidebar.vue -->
<script setup lang="ts">
import { ref, onMounted, onUnmounted } from 'vue'
import eventBus from '@/utils/eventBus'
const notification = ref('')
const handleNotification = (message: string) => {
  notification.value = message
  setTimeout(() => notification.value = '', 3000)
}
onMounted(() => {
  eventBus.on('notification', handleNotification)
})
onUnmounted(() => {
  eventBus.off('notification', handleNotification)
})
</script>

// src/utils/eventBusFactory.ts
import mitt from 'mitt'
export function createEventBus<T>() {
  return mitt<T>()
}
// 创建不同的事件总线
export const uiEventBus = createEventBus<{
  'modal-open': { id: string }
  'modal-close': string
}>()
export const dataEventBus = createEventBus<{
  'data-loaded': any[]
  'data-error': Error
}>()

// src/plugins/eventBus.ts
import { type App } from 'vue'
import mitt, { type Emitter } from 'mitt'
// 事件类型定义
type Events = {
  [key: string]: any
}
// 创建全局事件总线
const eventBus: Emitter<Events> = mitt<Events>()
export const EventBusPlugin = {
  install(app: App) {
    // 全局属性
    app.config.globalProperties.$eventBus = eventBus
    // 提供/注入
    app.provide('eventBus', eventBus)
  }
}
// 在 Composition API 中使用的 Hook
export function useEventBus() {
  const eventBus = inject<Emitter<Events>>('eventBus')
  if (!eventBus) {
    throw new Error('Event bus not provided')
  }
  return eventBus
}
export default eventBus

// main.ts
import { createApp } from 'vue'
import { EventBusPlugin } from '@/plugins/eventBus'
import App from './App.vue'
const app = createApp(App)
app.use(EventBusPlugin)
app.mount('#app')

// src/composables/useEventBus.ts
import { onUnmounted } from 'vue'
import eventBus, { type Handler } from '@/utils/eventBus'
export function useEventBus() {
  const listeners: Array<[string, Handler]> = []
  const emit = <T = any>(event: string, payload?: T) => {
    eventBus.emit(event, payload)
  }
  const on = <T = any>(event: string, handler: (payload: T) => void) => {
    eventBus.on(event, handler as Handler)
    listeners.push([event, handler as Handler])
  }
  const off = <T = any>(event: string, handler: (payload: T) => void) => {
    eventBus.off(event, handler as Handler)
    const index = listeners.findIndex(
      ([e, h]) => e === event && h === handler
    )
    if (index > -1) {
      listeners.splice(index, 1)
    }
  }
  const once = <T = any>(event: string, handler: (payload: T) => void) => {
    const onceHandler = (payload: T) => {
      handler(payload)
      off(event, onceHandler)
    }
    on(event, onceHandler)
  }
  // 自动清理监听器
  onUnmounted(() => {
    listeners.forEach(([event, handler]) => {
      eventBus.off(event, handler)
    })
    listeners.length = 0
  })
  return {
    emit,
    on,
    off,
    once
  }
}

<!-- 使用封装的 Hook -->
<script setup lang="ts">
import { useEventBus } from '@/composables/useEventBus'
const { emit, on, once } = useEventBus()
// 发送事件
const sendEvent = () => {
  emit('custom-event', { data: 'test' })
}
// 监听事件
on('custom-event', (payload) => {
  console.log('收到事件:', payload)
})
// 只监听一次
once('one-time-event', (payload) => {
  console.log('只会触发一次:', payload)
})
</script>

// 正确定义事件类型
type Events = {
  'user-updated': User
  'cart-changed': CartItem[]
}

// 组件卸载时取消监听
onUnmounted(() => {
  eventBus.off('event-name', handler)
})

const { emit, on } = useEventBus()
on('error-event', (error) => {
  // 统一错误处理
  console.error('事件错误:', error)
})