How to use event bus for component communication in Vue?

How to use event bus for component communication in Vue?

Overview:
In Vue applications, component communication is a very important part. When we need to transfer data or trigger events between different components, we can use Vue's event bus mechanism. Event bus is a central event manager used for communication between different components.

Implementation:
Event bus in Vue can be created and used through Vue instances. The following are the steps for using Vue's event bus for component communication:

Step 1: Create an Event Bus
Create an Event Bus somewhere in the project. It can be a separate js file or a Vue instance. For example, we can create a Vue instance as an Event Bus in the main.js file:

// main.js
import Vue from 'vue'

export const EventBus = new Vue()

Step 2: Send the event
In the component that needs to send the event, send the event through the Event Bus instance. Events can be sent using the $emit() method, which receives two parameters: the event name and the passed data.

// ComponentA.vue
import { EventBus } from '../main.js'

export default {
  methods: {
    sendData() {
      EventBus.$emit('refresh-data', data)
    }
  }
}

Step 3: Receive events
In the component that needs to receive events, receive events through the Event Bus instance. Events can be listened to using the $on() method, which receives two parameters: event name and callback function. The received data can be processed in the callback function.

// ComponentB.vue
import { EventBus } from '../main.js'

export default {
  data() {
    return {
      receivedData: ''
    }
  },
  mounted() {
    EventBus.$on('refresh-data', (data) => {
      this.receivedData = data
    })
  }
}

Through the above steps, we can achieve data transfer and event triggering between different components.

Example:
Suppose there are two components ComponentA and ComponentB, ComponentA is responsible for sending data, and ComponentB is responsible for receiving data.

// ComponentA.vue
<template>
  <div>
    <button @click="sendData">发送数据</button>
  </div>
</template>

<script>
import { EventBus } from '../main.js'

export default {
  methods: {
    sendData() {
      const data = 'Hello, ComponentB'
      EventBus.$emit('refresh-data', data)
    }
  }
}
</script>

// ComponentB.vue
<template>
  <div>
    <p>接收到的数据：{{ receivedData }}</p>
  </div>
</template>

<script>
import { EventBus } from '../main.js'

export default {
  data() {
    return {
      receivedData: ''
    }
  },
  mounted() {
    EventBus.$on('refresh-data', (data) => {
      this.receivedData = data
    })
  }
}
</script>

In the above example, clicking the button in ComponentA will send an event named 'refresh-data', which will be received in ComponentB and the received data will be updated.

Summary:
By using Vue’s event bus mechanism, we can easily achieve communication between components. Components that use Event Bus to create and send events act as publishers, while components that receive events act as subscribers. This decoupled approach can make communication between components more flexible and efficient.

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